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A STUDY ON ACHIEVING HIGHER STRENGTH CONCRETE USING CRUSHED BRICK AS COARSE AGGREGATE MOHAMMAD ASIF IQBAL DEPARTMENT OF CIVIL ENGINEERING DHAKA UNIVERSITY OF ENGINEERING & TECHNOLOGY, GAZIPUR July, 2012
Transcript of A STUDY ON ACHIEVING HIGHER STRENGTH CONCRETE ... - duet.ac.bd
A STUDY ON ACHIEVING HIGHER STRENGTH CONCRETE
USING CRUSHED BRICK AS COARSE AGGREGATE
MOHAMMAD ASIF IQBAL
DEPARTMENT OF CIVIL ENGINEERING
DHAKA UNIVERSITY OF ENGINEERING & TECHNOLOGY, GAZIPUR
July, 2012
A STUDY ON ACHIEVING HIGHER STRENGTH CONCRETE
USING CRUSHED BRICK AS COARSE AGGREGATE
A Thesis
By
MOHAMMAD ASIF IQBAL
Submitted to the Department of Civil Engineering,
Dhaka University of Engineering & Technology, Gazipur,
in partial fulfillment of the requirements for the degree of
MASTER OF SCIENCE IN CIVIL ENGINEERING
July, 2012
The thesis titled A Study on Achieving Higher Strength Concrete Using Crushed Brick
as Coarse Aggregate submitted by Mohammad Asif Iqbal, Student Number- 082104(P),
Session: 2009-2010 has been accepted as satisfactory in partial fulfillment of the requirement
for the degree of Master of Science in Civil Engineering on 08 July, 2012.
BOARD OF EXAMINERS
---------------------------------------- Chairman
Dr. Md. Nazrul Islam
Professor & Head
Department of Civil Engineering
DUET, Gazipur-1700.
---------------------------------------- Supervisor
Dr. Mohammad Abdur Rashid
Professor
Department of Civil Engineering
DUET, Gazipur-1700.
---------------------------------------- Member
Dr. Md. Khasro Miah
Professor
Department of Civil Engineering
DUET, Gazipur-1700.
---------------------------------------- Member
Dr. Md. Mozammel Hoque
Associate Professor
Department of Civil Engineering
DUET, Gazipur-1700.
---------------------------------------- Member
Dr. Md. Saiful Islam (External)
Professor
Department of Civil Engineering
CUET, Chittagong
CANDIDATE’S DECLARATION
It is hereby declared that this thesis or any part of it has not been submitted elsewhere for the
award of any degree.
Candidate’s Signature
-------------------------------
(Mohammad Asif Iqbal )
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ACKNOWLEDGEMENT
I would like to express my sincerest appreciation to my supervisor Professor Dr. Mohammad
Abdur Rashid, Department of Civil Engineering, DUET, Gazipur, for his guidance, expert
opinions and the investments he has made in me over the past more than two years, giving me
the opportunity to be involved in such interesting research activities.
I would like to acknowledge Prof. Dr. Md. Nazrul Islam Professor and Head, Department of
Civil Engineering, DUET, Gazipur and Professor, Dr. Mohammad Abdur Rashid,
Department of Civil Engineering, DUET, Gazipur, for making availability of the financial
support of the research work. I would like to thank all the member of Unique Ceramic Bricks,
Building Blocks Ltd. and Alam Brothers Syndicate Ltd, Konabari, Gazipur for giving me
some sample pieces of gas burnt picked bricks for testing of compressive strength of brick. I
would like to thank my friend Talha Moudut for giving me some electrical equipment which
was necessary for this research work.
Many people supported me in ways beyond what I would have asked for during the
completion of this research work. For this I would like to thank several mentors including
Md. Shafiq, and Mr. Mamun, Technical Officers of Civil Engineering Department. Also, I
would like to thank Mr. Jahangir, Mr. Iqbal, Mr. Samad and Mr. Ali Hossen, Lab staff of
Civil Engineering Department, for finding unique ways to encourage me and help me through
the good as well as difficult stages of this research work. I would like to thank Mr. Monirul
Hasan, Chief Chemist and all the member of Seven Circles (Bangladesh) Ltd, Kaligonj,
Gazipur for giving me fly ash which was very essential for my research work. I would like to
thank my grand father and mother (maternal) Mr. Mainul Hoque and Maksuda Khatun
respectively for praying for me in every step of life.
Most importantly, I would not be where I am today if it weren’t for the support and love of
my supervisor Professor, Dr. Mohammad Abdur Rashid and my parents, Bashir Uddin
Ahmed and Lutfun Nessa thank you for always helping me to my best.
July, 2012 Author
ii
Dedicated to my teacher Prof. Dr. Mohammad Abdur Rashid
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ABSTRACT
The study reported in this thesis is aimed at investigating the influences of major parameters
in achieving higher strength concrete using crushed clay brick as coarse aggregate. A total of
two hundred and ninety seven brick aggregate concrete cylinders have been tested in order to
investigate the influences of water/cement ratio, aggregate/cement ratio, coarse aggregate/fine
aggregate ratio, maximum size of coarse aggregate, and partial replacement of cement with
fly ash on the compressive strength of concrete. The water/cement ratios considered were
0.60, 0.50, and 0.40 (by weight) whereas the aggregate/cement ratios were 6.0, 4.5, and 3.0
(by volume). The coarse aggregate/fine aggregate ratios were considered as 1.5, 2.0, and 2.5
(by volume). Maximum sizes of coarse aggregates were 12.5 mm, 19.0 mm, and 25.0 mm.
And the replacements of cement with fly ash were considered as 10% and 20%. The standard
size cylindrical specimens (150×300 mm) were considered in this study. The ordinary
Portland cement was used and the test specimens were tested for crushing strength of
concrete at the age of 28 days (except a few cases).
From the test results it has been found that the influence of water/cement ratio on
compressive strength of concrete is increased about 26.0% and 14.4% when the water/cement
ratio was decreased from 0.60 to 0.50 and 0.50 to 0.40 respectively. Again an increase in
compressive strengths of about 9.7% and 7.0% are found when the aggregate/cement ratio
was decreased from 6.0 to 4.5 and 4.5 to 3.0 respectively. The compressive strengths of
concretes are found to be highest for the coarse aggregate/fine aggregate ratio (by volume) of
2.0. The average value of the compressive strengths of concretes with coarse aggregate/fine
aggregate ratio of 1.5, 2.0, and 2.5 are found to be 27.41, 31.18, and 24.20 MPa respectively.
In this study the maximum size of coarse aggregate is found to have no significant influence
on the concrete compressive strengths. The average values of the compressive strengths of
concretes with maximum size of coarse aggregate of 12.5, 19.0, and 25.0 are found to be
27.71, 28.10, and 26.99 MPa respectively.
At early ages the rate of strength development is found to be lower for concrete containing fly
ash (partial) and the difference between the strengths of concretes with and without fly ash is
found to decrease with the increase in concrete age. The 28-days average strength of
concretes containing fly ash (10% and 20%) is found to be 90% of that of the concrete
without any fly ash. And the difference between the strengths of these concretes becomes
much smaller at 90 days.
The water/cement ratio has the highest influence on the compressive strength of brick
aggregate concrete. Next influential parameter is seen to be the total aggregate/cement ratio
followed by that of the maximum size of coarse aggregate. In this study, a concrete with
compressive strength of 37.97 MPa has been achieved considering water/cement ratio of 0.5,
maximum size of coarse aggregate of 12.5 mm and a mix ratio of 1:1:2 by volume.
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CONTENTS
Title Page No
ACKNOWLEDGEMENT i
ABSTRACT iii
CONTENTS iv
NOTATION AND ABBREVIATION vi
LIST OF TABLES vii
LIST OF FIGURES viii
CHAPTER 1 INTRODUCTION
1.1 General 1
1.2 Back ground of the study 2
1.3 Objective of the study 5
1.4 Scope of the study 5
CHAPTER 2 LITERATURE REVIEW
2.1 General 6
2.2 Basic ingredients of concrete 6
2.2.1 Cement 7
2.2.1.1 Hydration of cement 9
2.2.2 Aggregates 10
2.2.3 Water 13
2.2.4 Fly ash 14
2.2.4.1 Chemical composition of fly ash (ASTM C618, 1998) 15
2.2.4.2 Hydration mechanisms of fly ash 16
2.3 Factors influencing the strength of concrete 17
2.3.1 The Influence of water/cement ratio on the strength of concrete 18
2.3.2 The Influence of aggregat/cement ratio on the concrete strength 19
2.3.3 Influence of the coarse aggregate/fine aggregate ratio on concrete strength 21
2.3.4 Influence of maximum size of coarse aggregate on the strength of concrete 21
2.3.5 Influence of replacing cement by fly ash on concrete strength 23
CHAPTER 3 EPREMENTAL INVESTIGATIONS
3.1 General 25
3.2 Test program 25
v
3.3 Properties of ingredients used for making concrete 27
3.3.1 Cement 27
3.3.2 Coarse and fine aggregates 29
3.3.3 Water 30
3.3.4 Fly ash 31
3.4 Preparation of test specimens 32
3.4.1 Preparation of coarse aggregate 32
3.4.2 Casting cylindrical specimens 32
3.4.3 Curing of specimens 33
3.5 Testing of cylindrical specimens 34
3.5.1 Preparing the test specimens 34
3.5.2 Testing of the specimens 34
3.5.3 Test results 35
CHAPTER 4 ANALYSIS AND DISCUSSIONS ON TEST RESULTS
4.1 General 40
4.2 Concrete strengths obtained from test data 40
4.3 Influence of various parameters on concrete compressive strength 40
4.3.1 Influence of water/cement ratio on compressive strength 41
4.3.2 Influence of aggregate/cement ratio on compressive strength 45
4.3.3Influence of coarse aggregate/fine aggregate ratio on compressive strength 49
4.3.4 Influence of maximum size of CA on compressive strength 53
4.3.5 Influence of the partial replacement of cement by fly ash on concrete
strength 58
4.3.6 Comparison among of various parameters influencing concrete strength 59
CHAPTER 5 CONCLUSIONS & FUTURE RECOMMENDATION
5.1 General 60
5.2 Conclusions 60
5.3 Recommendations for future study 61
REFERENCES 63
APPENDIX-A PROPERTIES OF MATERIALS USED 66
APPENDIX-B TEST DATA 74
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NOTATIONS AND ABBREVIATIONS
A = Cross sectional area of concrete sample
AD = Air dry
A/C = Aggregate to cement ratio
CA = Coarse aggregate
CA/FA = Coarse aggregate to fine aggregate ratio
C3A = Tricalcium aluminate
C4AF = Tetracalcium alumino ferrite
C2S = Dicalcium silicate
C3S = Tricalcium silicate
/
cf = Cylindrical compressive strength of concrete
FA = Fine aggregate
FM = Fineness modulus
OD = Oven dry
P = Load applied to the sample
SSD = Saturated surface dry
TA = Total aggregate
W/C = Water to cement ratio
W/B = Water to binder ratio
ACI = American Concrete Institute
ASTM = American Society for Testing Materials
CFA = Classified fly ash
DUET = Dhaka University of Engineering & Technology
OFC = Original fly ash
OPC = Ordinary Portland cement
PC = Portland cement
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LIST OF TABLES
Table no. Title of Table Page no.
Table 2.1 Basic compounds of cement 7
Table 3.1 Mix ratios and related variables for the first phase of study 26
Table 3.2 Mixes of the second phase of experimental study 27
Table 3.3 Properties of the cement used in the experiment 28
Table 3.4 Oxide Composition of Ordinary Portland cement 28
Table 3.5 Principal Components of Ordinary Portland cement 29
Table 3.6 Properties of fine aggregates used 29
Table 3.7 Properties of coarse aggregates used 30
Table 3.8 Properties of fly ash used (as provided by the supplier) 31
Table 3.9 Concrete mix variables and their compressive strengths 35
Table 3.10 Fly ash concrete mix variables and their compressive strengths 39
Table 4.1 Relative influence of test variables on increasing concrete strength 59
viii
LIST OF FIGURES
Fig. no Title of Figure Page no.
Fig. 1.1 The relation between strength and water/cement ratio of concrete (Neville, 1995) 03
Fig. 1.2 Influence of maximum size of aggregate on concrete strength (Shetty, 1988) 04
Fig. 2.1 Strength versus various combinations of cements and pozzolans (Caldarone, 2009) 19
Fig. 2.2 Effect of aggregate/cement ratio on the strength of concrete (Neville, 1995) 20
Fig. 2.3 Typical relation between concrete strength and aggregate/cement ratio for
various compacting factors (Bureau of Indian Standards, 1990) 21
Fig. 2.4 Influence of maximum size of aggregate on concrete strength (Duggal, 2008) 22
Fig. 3.1 Coarse aggregate used in the study 30
Fig. 3.2 Fine aggregate used 30
Fig. 3.3 Compaction of fresh concrete using vibrator 33
Fig. 3.4 Curing of concrete specimens 33
Fig. 3.5 Grinding of concrete cylinder 34
Fig. 3.6 Testing of concrete cylinder 35
Fig. 4.1 (a) Influence of water/cement ratio on compressive strength of concrete with
A/C = 3.0 41
Fig. 4.1 (b) Influence of water/cement ratio on compressive strength of concrete with
A/C = 4.5 42
Fig. 4.1 (c) Influence of water/cement ratio on compressive strength of concrete with
A/C = 6.0 43
Fig. 4.2 Variation in concrete strength with the variation in water/cement ratio 44
Fig. 4.3 (a) Influence of aggregate/cement ratio on compressive strength of concrete with
W/C =0.40 45
Fig. 4.3 (b) Influence of aggregate/cement ratio on compressive strength of concrete with
W/C =0.50 46
Fig. 4.3 (c) Influence of aggregate/cement ratio on compressive strength of concrete with
W/C =0.60 47
Fig. 4.4 Variation in concrete strength with the variation in aggregate/cement ratio 48
Fig. 4.5 (a) Influence of coarse aggregate/fine aggregate ratio on compressive strength
of concrete with W/C =0.40 50
Fig. 4.5 (b) Influence of coarse aggregate/fine aggregate ratio on compressive strength of
concrete with W/C =0.50 51
Fig. 4.5 (c) Influence of coarse aggregate/fine aggregate ratio on compressive strength of concrete
with W/C =0.60 52
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Fig. 4.6 Variation in concrete strength with the variation in CA/FA ratio 53
Fig. 4.7 (a) Influence of maximum size of CA on compressive strength of concrete with
W/C =0.40 54
Fig. 4.7 (b) Influence of maximum size of CA on compressive strength of concrete with
W/C =0.50 55
Fig. 4.7 (c) Influence of maximum size of CA on compressive strength of concrete with
W/C =0.60 56
Fig. 4.8 Variation in concrete strength with the variation in max size of CA 57
Fig. 4.9 Influence of fly ash on compressive strength of concrete 58
1
CHAPTER 1
INTRODUCTION
1.1 General
Concrete is the most widely used man-made construction material. It is obtained by mixing of
cement, water and aggregates (and sometimes admixtures) in required proportions. The
compressive strength of concrete is commonly considered its most valuable property,
although, in many practical cases, other characteristics such as durability and permeability
may in fact be more important. Nevertheless, strength usually gives an overall picture of the
quality of the concrete. Moreover, the strength of concrete is almost invariably a vital element
of structural design and is specified for compliance purpose.
Concrete, a composite consisting of aggregates enclosed in a matrix of cement paste
including possible pozzolans, has two major components–cement paste and aggregate
(Rashid and Mansur, 2009). In the developing countries like Bangladesh, concrete in the
structural system of buildings and bridges are referred to as a key element and it takes all or
major part of compression in the structural elements. To achieve higher strength concretes,
optimum proportions must be selected considering the properties and proportions of its
ingredient materials. Variation in the chemical composition and physical properties of the
cement affect the concrete compressive strength more than variations in any other single
materials. There is optimum cement content beyond which little or no additional increase in
strength is achieved from increasing the cement content. Finely divided cementitious
materials other than cement, consisting mainly of fly ash have also been considered in the
production of higher strength concrete. This material can help control the temperature rise in
concrete at the early stage and may reduce the water demand for a given workability.
However, early strength gain of the concrete may be decreased. The acceptability of the water
for higher strength concrete is not of major concern if potable water is used.
The aggregates require special consideration since they occupy the largest volume of any
ingredient in the concrete, and they greatly influence the strength and other properties of
concrete. The coarse aggregate will influence significantly the strength and structural
properties of the concrete. Larger maximum size of coarse aggregate gives lower surface area
for developments of gel bonds which is responsible for the lower strength of the concrete.
2
Secondly bigger aggregate size causes a more heterogeneity in the concrete which will
prevent the uniform distribution of load when stressed. Generally, high strength concrete or
rich concrete is adversely affected by the use of large size aggregate (Shetty, 1988). For this
reason, a coarse aggregate should be chosen that is sufficiently hard, free of weak planes,
clean and free of surface coatings. Coarse aggregate properties also affect aggregate-mortar
bond characteristics and mixing water requirements. Smaller size aggregates have been
shown to provide higher strength potential. The grading and particles shape of the fine
aggregate are significant factors in the production of higher strength concrete. The quantity of
cement required per unit volume of a concrete mixture decreases as the relative volume of
coarse aggregate versus fine materials increases (ACI Committee 211, 1998).
1.2 Background of the Study
The strength of concrete results from: (i) the strength of the mortar; (ii) the bond between the
mortar and the coarse aggregate; and (iii) the strength of the coarse aggregate particles. For a
given cement and acceptable aggregate, the strength that may be developed by a workable,
properly placed mixture of cement, aggregates, and water (under the same mixing curing, and
testing conditions) is influenced by the following factors (Neville, 1995; Shetty, 1988;
Gambhir, 1993; Rashid and Mansur, 2009):
(a) Ratio of cement to mixing water.
(b) Ratio of cement to aggregate.
(c) Maximum size of aggregate
(d) Grading, surface texture, shape, strength, and stiffness of aggregate particles.
The strength of concrete primarily depends upon the strength of cement paste. Whereas the
strength of cement paste increases with cement content and decreases with air and water
content. When concrete is fully compacted, its strength is taken to be inversely proportional
to the water/cement ratio. This relation was preceded by a so-called `law’ but really a rule,
established by Duff Abrams in 1919. He found strength to be equal to:
cwc
K
Kf
/
2
1=′ (1.1)
Where W/C represents the water/cement ratio of the mix by volume, and for 28 days results
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the constants K1 and K2 are 14000 lb/in2 (psi) and 7 respectively. The general form of the
strength versus water/cement ratio curve is shown in Fig. 1.1 (Shetty, 1988; Neville, 1995).
The aggregate/cement ratio is a secondary factor in the strength of concrete but it has been
found that for a constant water/cement ratio, a leaner mix leads to a higher strength. This lies
in the fact that the total water content per cubic meter of concrete is lower in a leaner mix
than in a rich one. As a result, in a leaner mix, the voids form a smaller fraction of the total
volume of concrete, and it is these voids that have an adverse effect on the strength of
concrete (Neville, 1995).
Fig. 1.1 The relation between strength and water/cement ratio of concrete (Neville, 1995)
The larger maximum size aggregates yield lower strength to concrete. This is because, firstly,
the larger maximum size aggregate gives lower surface area for developments of gel bonds
which is responsible for the lower strength of the concrete. Secondly, bigger aggregate size
causes a more heterogeneity in the concrete which will prevent the uniform distribution of
load when stressed. Generally high strength concrete or rich concrete is adversely affected by
the use of large size aggregate. But in lean mixes or weaker concrete the influence of size of
the aggregate gets reduced. It is interesting to note that in lean mixes larger aggregate gives
highest strength while in rich mixes it is the smaller size aggregate which yield higher
strength. Fig. 1.2 shows the influence of maximum size of aggregate on the compressive
strength of concrete (Shetty, 1988).
In Bangladesh, where natural rock deposits are scarce, burnt clay bricks are used as an
alternative source of coarse aggregate. Here the use and performance of concrete made with
4
broken brick as coarse aggregate are quite extensive and satisfactory. In spite of extensive use
of brick aggregate concrete and the apparent satisfactory performance of the structures
already built, no systematic investigation was conducted and properly documented. The
current designs for brick aggregate concrete are based on intuition and accumulation of
experience, rather than on sound experimental evidence (Rashid, Hossain, and Islam, 2009).
Fig. 1.2 Influence of maximum size of aggregate on concrete strength (Shetty, 1988)
The practical experiences confidently showed us that the maximum range of compressive
strength of concretes made with brick aggregate but without using any admixture is around
3000 psi. However, higher strength concrete ( /
cf much greater than 3000 psi) can be used
advantageously in compression members such as columns and piles. In columns, the
reduction in size will lead to reduced dead load and subsequently to reduced total load on the
foundation system. Smaller column size also means more available floor space to use. The
relatively higher compressive strength per unit volume will also significantly reduce the dead
load of other reinforced concrete members. In addition, higher strength concrete possessing a
highly dense microstructure is likely to enhance long-term durability of the structure (Rashid,
Hossain and Islam, 2009).
A few studies on higher strength concrete using brick aggregates have been reported in the
literature (Rashid, and Islam, 2009; Mansur, Wee and Cheran, 1999; Khaloo, 1994;
5
Akhtarurzzaman and Hasnat, 1983). The present study, therefore, has aimed at to study the
influences of major parameters in achieving higher strength concrete using broken bricks as
coarse aggregate.
1.3 Objective of the Study
This study intends to achieve the following goals on the concrete made with crushed brick as
coarse aggregate:
(i) To study the effect of water/cement ratio on the strength of concrete.
(ii) To investigate the influence of the aggregate content of concrete on the strength.
(iii) To investigate the influence of the coarse aggregate/fine aggregate ratio on the concrete strength.
(iv) To investigate the influence of the maximum size of coarse aggregate on the concrete strength.
(v) To study the effect of replacing (partially) cement by equal weight of fly ash on the concrete strength.
(vi) To make a comparative study among the influences of major parameters of brick aggregate concrete in increasing its strength.
1.4 Scope of the Study
Followings are the scope of the present study:
(i) Cylindrical compressive strength ( /
cf ) of concrete made with brick aggregate and
Ordinary Portland cement (ASTM Type-I) has been studied.
(ii) Water/cement ratio (by weight) considered are 0.40, 0.50, and 0.60
(iii) Aggregate/cement ratio (by volume) considered are 3.0, 4.5, and 6.0.
(iv) Coarse aggregate/fine aggregate ratio (by volume) considered are 1.5, 2.0, and 2.5.
(v) Maximum sizes of coarse aggregate used in the concrete are 12.5 mm, 19.0 mm, and 25.0 mm.
(vi) Replacements (by weight) of cement by fly ash considered are 10% and 20%.
6
CHAPTER 2
LITERATURE REVIEW
2.1 General
Concrete is a versatile construction material. Among the various properties, the compressive
strength of a concrete is the most desirable property as its value indicates the overall quality
of that concrete. However, the strength of a well mixed, properly cast and continuously cured
concrete depends mainly on the properties and the proportions of its ingredient materials. The
bulk of the concrete consists of fine and coarse aggregates. Cement and water interact
chemically to bind the aggregate particles into a solid mass. Additional water, above that
needed for this chemical reaction, is necessary to give the workability that enables it to fill
the forms and surround the embedded reinforcing steel prior to hardening. Concrete in a wide
range of strength properties can be obtained by appropriate adjustment of the proportions of
the constituent materials (Cordon and Thorpe, 1975). A literature survey has been done in
order to investigate the major parameters which influence the strength of the concrete made
with broken bricks as coarse aggregate.
2.2 Basic Ingredients of Concrete
Concrete is obtained by mixing cement, water and aggregates (and sometimes admixtures) in
required proportions. The mixture when placed in forms and allowed to cure becomes hard
like stone. The hardening is caused by chemical action between water and the cement and it
continues for a long time, and consequently the concrete grows stronger with age. The
hardened concrete may also be considered as an artificial stone in which the voids of larger
particles (coarse aggregate) are filled by the smaller particles (fine aggregate) and the voids
of fine aggregates are filled with cement. In a concrete mix the cement and water form a paste
called cement-water paste which in addition to filling the voids of fine aggregate acts as
binder on hardening, thereby cementing the particles of the aggregates together in a compact
mass.
The basic elements of concrete are cement, water, fine aggregates and coarse aggregates.
Recently some admixture like fly ash is also used in concrete. A brief review of the basic
elements of concrete is presented in the following articles.
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2.2.1 Cement
Although all materials that go into a concrete mixture are essential, cement is by far the most
important constituent because it is usually the delicate link in the chain. Cement is an
extremely ground material having adhesive and cohesive properties, which provide a binding
medium for the discrete ingredients. It is obtained by burning together, in a definite
proportion, a mixture of naturally occurring argillaceous (containing alumina) and calcareous
(containing calcium carbonate or lime) materials to a partial fusion at high temperature (about
1450oC). The product obtained on burning, called clinker, is cooled and ground to the
required fineness to produce a material known as cement. Its inventor, Joseph Aspdin, called
it Portland cement because when it is hardened it produced a material resembling stone from
the quarries near Portland in England.
The composition of cement is rather complicated but basically it consists of the following
four main compounds (Table 2.1).
Table 2.1 Basic compounds of cement
Compound Percentage by
mass in cement Name Formula Abbreviation
Tri-calcium silicate 3CaO.SiO2 C3S 30 – 50
Di-calcium silicate 2CaO.SiO2 C2S 20 – 45
Tri-calcium aluminate 3CaO.Al2O3 C3A 8 – 12
Tetra-calcium alumino ferrite 4CaO. Al2O3.Fe2O3 C4AF 6 – 10
The function of cement is first, to bind the fine and coarse aggregates together and second, to
fill the voids in between fine and coarse aggregate particles to form a compact mass.
Although cement constitutes only about 10% of the volume of the concrete mix, it is the
active portion of the binding medium and the only scientifically controlled ingredient of
concrete.
8
Tri-calcium silicate (C3S) constitutes about 45 percent of the cement & is very important
constituent from the consideration of strength giving properties. C3S hydrates and hardens
rapidly and is largely responsible for initial set and early strength. In general, the early
strength of Portland cement concrete is higher with increased percentages of C3S. At the end
of one year the two compounds viz. C3S & C2S, weight for weight, contribute approximately
equally to the ultimate strength. The influence of the other major compounds on the strength
development of cement has been established less clearly. Cement with higher C3S content is
better for cold weather concreting.
Di-calcium silicate (C2S) constitutes about 25 percent of the cement & is very important
constituent from the consideration of strength giving properties. C2S hydrates and hardens
slowly and contributes largely to strength increase at ages beyond one week. A convenient
approximate rule assumes that C3S contributes most to the strength development during the
first 4 weeks and C2S influences the gain in strength from four weeks onwards. At the end of
one year the two compounds, weight for weight, contribute approximately equally to the
ultimate strength. The influence of the other major compounds on the strength development
of cement has been established less clearly.
Tri-calcium aluminate (C3A) liberates a large amount of heat during the first few days of
hydration and hardening. The influence of C3A on strength development of cement has been
established less clearly. C3A contributes to the strength of cement paste at one or three days
,and possibly longer, but causes retrogression at an advanced stage, particularly in cements
with high C3A or (C3A+ C4AF) content. The role of C3A is still controversial. Cements with
low percentages of C3A are more resistant to soils and waters containing sulphates. The
amount of tri-calcium aluminate present may well be limited as in the case of sulphate
resisting Portland cement, to prevent adverse reactions between the hydrate and sulphates
from the environment which can result in swelling and cracking of the cement matrix. The
great advantage of tri-calcium aluminate is its ability to combine with chlorides, so removing
them from the liquid phase of the cement. The presence of C3A in cement contributes little or
nothing to the strength of the cement except at early ages, and when hardened cement paste is
attacked by sulphates, expansion due to the formation of calcium sulphoaluminate from C3A
may result in disruption of the hardened paste. However, C3A acts as a flux and thus reduces
the temperature of burning of clinker and facilitates the combination of lime & silica. For this
reason C3A is useful in manufacture of cement.
9
Tetracalcium Aluminoferrite (C4AF) is the product resulting from the use of iron and
aluminum raw materials to reduce the clinkering temperature during cement manufacture.
The role of C4AF in the strength development is also debatable, but it can be said with
certainty that there is no appreciable positive contribution. Most color effects that make
cement gray are due to C4AF and its hydrates. C4AF also acts as a flux.
2.2.1.1 Hydration of cement
The extent of hydration of cement and the resultant microstructure of hydrated cement
influences the physical properties of concrete. The micro structure of hydrated cement is
more or less similar to those of silicate phases. When the cement comes in contact with water,
the hydration of cement proceeds both inward and outward in the sense that the hydration
products get deposited on the outer periphery and the nucleus of the unhydrated cement
inside gets gradually diminished in volume. The reaction proceeds slowly for 2-5 hours
(called induction or dormant period) before accelerating as the surface skin breaks. At any
stage of hydration having calcium hydroxide Ca (OH) 2, and water, besides some other minor
compounds. The crystals of various resulting compounds form an interlocking random three-
dimensional work gradually filling the space originally occupied by the water, resulting in
stiffening and subsequent development of strength. Accordingly, the hardened cement paste
has a porous structure, the pore size varying from every small (4x10-4 μm) to a much larger
value, the pores being called gel pores and capillary pores respectively. The pore system
inside the hardened cement paste may not be continuous. As the hydration proceeds, the
deposit of hydration products on the original cement grain makes the diffusion of water to
unhydrated nucleus more and more difficult thus reducing the rate of hydration with time.
The reactions of compounds and their products may be symbolically represented as:
C3S+H2O C – S – H*+Ca (OH) 2 Silicate Phase
C2S+H2O C – S – H+ Ca (OH) 2
C3A+ H2O C4AH13+C2AH8 C3AH6
C3A+ H2O+CaSO4 C3A. 3CŜH32 CA. CSH12
C4AF+ H2O C3AH6+CFH
The product C-S-H represents the calcium silicate hydrate which is the gel structure. The
above equations only refer to the processes in which the cement compounds (C3S and C2S
etc.) react with water to form a strong hydrated mass. The hydrated crystals are extremely
10
small, varying from colloidal dimensions (less than 2 μm) to 10 μm or more. The Ca (OH) 2
liberated during the reaction of silicate phase crystallizes in the available free space
(Gambhir, 1993).
C3A reacts from beneath the thin member of calcium sulphoaluminate formed on the C3A
surface. Owing to the larger volume of calcium sulphoaluminate, pressure develops and the
membrane eventually bursts, allowing the sulphate in solution to come in contact with
unreacted C3A to reform the membrane. The cyclic process continues until all the sulphate in
solution is consumed, whereupon the C3A can hydrate directly at a faster rate and the
transformation of calcium sulphoaluminate into needle like monosulphate crystals leads to
the loss of workability and to setting. This gives rise to the induction period which ends when
the protective membrane is disrupted. Although the reaction between C3S and water proceeds
at the same time, in properly retarded cement the end of induction period of C3S hydration
coincides with the point at which sulphate in solution is no longer available for reaction.
Setting now is due to the simultaneous growth of aluminate hydrate, monosulphate and
silicate hydrated in the inter-particle space. The above theory is termed the protective
membrane layer theory (Gambhir, 1993).
The reaction of the compound C3A with water is very fast in that flash setting, i.e., stiffening
without strength development, can occur because the C-A-H phase prevents the hydration of
C3S to form insoluble calcium sulphoaluminate which deposits on the surface of the C3A to
form a protective colloidal membrane and thus retard the direct hydration reaction. When all
the sulphate is consumed, hydration can accelerate. The amount of sulphate must, therefore,
be carefully controlled to leave little excess C3A to hydrate directly. The hardening of C3S
appears to be catalyzed by C3A so that C3S becomes almost solely responsible for the gain of
strength up to about 28 days by growth and interlocking of C-S-H gel. The later age increase
in strength is due to the hydration of C2S. The rate of strength development can, therefore, be
modified by changes in the relative qualities of these compounds (Gambhir, 1993).
2.2.2 Aggregates
The aggregates provide about 75% of the body of the concrete and hence its influence is
extremely important. They should, therefore, meets certain requirements if the concrete is to
be workable, strong, durable, and economical. The aggregate must be of proper shape (either
rounded or approximately cubical), clean, hard, strong, and well graded. It should possess
11
chemical stability, and, in many cases, exhibit abrasion resistance and resistance to freezing
and thawing.
The aggregates used in concrete range from few centimeters or more, down to a few microns.
The maximum size of the aggregate may vary, but in each case it is to be so graded that the
particles of different size fractions are incorporated in the mix in appropriate proportions. The
particle size distribution is called the grading of the aggregate. According to size the
aggregate is classified as: fine aggregate and coarse aggregate. The aggregate whose size is
4.75 mm and less is considered as fine aggregate whereas the size of coarse aggregate is
bigger than 4.75 mm. Perhaps, 80 mm size is the maximum size that could be conveniently
used for concrete making. In general, for concrete strengths up to 20 N/mm2 aggregate up to
40 mm may be used, and concrete strengths above 30 N/mm2, aggregates up to 20 mm may
be used. Sand is generally considered to have a lower size limit of about 0.07 mm.
Aggregates are important constituent in concrete. They reduce shrinkage of concrete. Earlier,
aggregate were considered as chemically inert materials but now it has been recognized that
some of the aggregates are chemically active and also that certain aggregates exhibit
chemical bond at the interface of aggregate and paste. The mere fact that the aggregates
occupy 70-80 percent of the volume of concrete, their impact on various characteristics and
properties of concrete is undoubtedly considerable (Shetty, 1988). To know more about the
concrete it is very essential that one should know more about the aggregates which constitute
major volume in concrete. Without the study of the aggregate in depth and range, the study of
the concrete is incomplete. Cement is the only factory made standard compound in concrete.
Other ingredient, namely, water and aggregates are natural materials and can very to any
extent in many of their properties. The depth and range of studies that are required to be made
in respect of aggregates to understand their widely varying effects and influence on the
properties of concrete cannot be underrated.
Aggregate is classified as two different types, coarse and fine. Coarse aggregate is usually
greater than 4.75 mm (retained on a No. 4 sieve), while the size of fine aggregate is less than
4.75 mm (passing through the No. 4 sieve). The compressive strength of aggregate is an
important factor in the selection of aggregate. When determining the strength of normal
concrete, natural aggregates are several times stronger than the other components in concrete
whereas the strength of brick aggregates may control the strength of concrete. Other physical
12
and mineralogical properties of aggregate must be known before mixing concrete to obtain a
desirable mixture. These properties include shape and texture, size gradation, moisture
content, specific gravity, absorption capacity, and bulk unit weight. These properties along
with the water/cementitious material ratio determine the workability, strength, and durability
of concrete.
The shape and texture of aggregate affects the properties of fresh concrete more than
hardened concrete. Concrete is more workable when smooth and rounded aggregate is used
instead of rough angular or elongated aggregate. Most natural sands and gravel from
riverbeds or seashores are smooth and rounded and are excellent aggregates with respect to
concrete’s workability. Crushed stone produces much more angular and elongated
aggregates, which have a higher surface-to-volume ratio, better bond characteristics but
require more cement paste to produce a workable mixture. The surface texture of aggregate
can be either smooth or rough. A smooth surface can improve workability, yet a rougher
surface generates a stronger bond between the paste and the aggregate creating a higher
strength.
The grading or size distribution of aggregate is an important characteristic because it
determines the paste requirement for workable concrete. This paste requirement is the factor
controlling the cost, since cement is the most expensive component. It is therefore desirable
to minimize the amount of paste consistent with the production of concrete that can be
handled, compacted, and finished while providing the necessary strength and durability. The
required amount of cement paste is dependent upon the amount of void space that must be
filled and the total surface area of aggregate that must be covered. When the particles are of
uniform size the spacing is the greatest, but when a range of sizes is used the void spaces to
be filled and hence the paste requirement is lowered. The more these voids are filled, the less
workable the concrete becomes, therefore, a compromise between workability and economy
is necessary.
The moisture content of an aggregate is an important factor when determining the proper
water/cementitious material ratio. All aggregates contain some moisture based on the porosity
of the particles and the moisture condition of the storage area. The moisture content can range
from less than one percent in gravel to up to 25 percent in case of normal brick aggregate.
13
Aggregate can be found in four different moisture states that include oven-dry, air-dry,
saturated-surface dry and wet. Of these four states, only oven-dry and saturated-surface dry
correspond to specific moisture state and can be used as reference states for calculating
moisture content. In order to calculate the quantity of water that aggregate will either add to
or subtract from the paste, the following three quantities must be calculated: absorption
capacity, effective absorption, and surface moisture.
Most stockpiled coarse aggregate is in the air-dry state with absorption of less than one
percent, but most fine aggregate is often in the wet state with surface moisture up to five
percent. This surface moisture on the fine aggregate creates a thick film over the surface of
the particles pushing them apart and increasing the apparent volume. This is commonly
known as bulking and can cause significant errors in proportioning volume.
The density of the aggregates is required in mixture proportioning to establish weight-volume
relationships. Specific gravity is easily calculated by determining the densities by the
displacement of water. All aggregates contain some porosity, and the specific gravity value
depends on whether these pores are included in the measurement. There are two terms that
are used to distinguish this measurement; absolute specific gravity and bulk specific gravity.
Absolute specific gravity refers to the solid material excluding the pores, and bulk specific
gravity, sometimes called apparent specific gravity, includes the volume of the pores. For the
purpose of mixture proportioning, it is important to know the space occupied by the
aggregate particles, including the pores within the particles. The bulk specific gravity of an
aggregate is not directly related to its performance in concrete, although, the specification of
bulk specific gravity is often done to meet minimum density requirements.
For mixture proportioning, the bulk unit weight is required. The bulk density measures the
volume that the graded aggregate will occupy in concrete, including the solid aggregate
particles and the voids between them. Since the weight of the aggregate is dependent on the
moisture content of the aggregate, constant moisture content is required. This is achieved by
using oven-dry aggregate. Additionally, the bulk density is required for the volume method of
mixture proportioning.
2.2.3 Water
Water is the most important and least expensive ingredient of concrete. A part of mixing
14
water is utilized in the hydration of cement to form the binding matrix in which the inert
aggregates are held in suspension until the matrix has hardened. The remaining water serves
as a lubricant between the fine and coarse aggregates and makes concrete workable.
Generally, cement requires about ¼ of its weight of water for hydration. Hence, the minimum
water/cement ratio required is 0.30. But the concrete containing water in this proportion will
be very harsh and difficult to place. Additional water is required to lubricate the mix, which
makes the concrete workable. This additional water must be kept to the minimum, since too
much water reduces the strength of concrete. The water/cement ratio is influenced by the
grade of concrete, nature and type of aggregates, the workability and durability, etc. The
water used for mixing and curing of concrete should be free from injurious amounts of
deleterious materials. A popular yard-stick to the suitability of water for mixing concrete is
that, if water is fit for drinking it is fit for making concrete. Some specifications also accept
water for making concrete if the pH value of water lies between 6 and 8 and the water is free
from organic matter. Instead of depending upon pH value and other chemical composition,
the best course to find out whether a particular source of water is suitable for concrete making
or not, is to make concrete with this water and compare its 7 day’s and 28 day’s strengths
with those of companion cylinders made with distilled water. If the compressive strength is
up to 90%, the source of water may be accepted.
Water containing large quantities of chlorides, i.e. sea water, tends to cause persistent
dampness and surface efflorescence. Sea water increases the corrosion of the reinforcing
steel. Algae may be present in mixing water or on the surface of aggregate particles. It
combines with the cement and reduces the bond between aggregates and cement paste. The
water containing algae has the effect of entraining large quantities of air in the concrete and
thus lowering the strength of concrete. The water which is satisfactory for mixing concrete
can also be used for curing it but should not produce any objectionable stain or unsightly
deposit. Iron and organic matter in the water are chiefly responsible for staining or
discoloration and especially when concrete is subjected to prolonged wetting, even a very low
concentration of these can cause staining.
2.2.4 Fly ash
Fly ash, known also as pulverized-fuel ash, is the ash precipitated electro statically or
mechanically from the exhaust gases of coal-fired power stations; it is the most common
15
artificial pozzolana. The fly ash particles are spherical (which is advantageous from the water
requirement point of view) and have a very high fineness: the vast majority of particles have
a diameter between less than 1 μm and 100 μm, and the specific surface of fly ash is usually
between 250 and 600 m2/kg, using the Blaine method. The high specific surface of the fly ash
means that the material is readily available for reaction with calcium hydroxide (Neville,
1995).
ASTM broadly classification fly ash into two classes:
CLASS F: Fly ash normally produced by burning anthracite or bituminous coal, usually has
less than 5% CaO. Class F fly ash has pozzolanic properties only. Most effectively moderates
heat gain during concrete curing and is therefore considered an ideal material in mass
concrete and high strength mixes. For the same reason, class F is the solution to a wide range
of summer concreting problems. This type of fly ash provide sulfate resistance superior to
type V cement. For the exposure area where concrete may be attacked by sulfate ions, Class F
is often recommended.
Class C: Fly ash is normally produced by burning lignite or sub-bituminous coal. Some class
C fly ash may have Cao content in excess of 10%. In addition to pozzolanic properties, class
C fly ash also possesses cementitious properties. Whereas both types of fly ash impart a wide
range of qualities to many types of concretes, they differ chiefly in the following ways. This
type of fly ash is the most useful in “performance” mixes, pre-stressed applications and other
situations where early strengths are important. Especially it is useful in soil stabilization since
Class C may not require the addition of lime. Concrete manufacturers, engineers, developers,
architects and contractors all have an interest in specifying or using fly ash on a routine bases
to improve the quality of their project and to increase their cost effectiveness.
2.2.4.1 Chemical composition of fly ash (ASTM C618, 1998)
The chemical composition of fly ash and ordinary Portland cement are very similar to each
other. Fly ash is amorphous (glassy) due to rapid cooling whereas Portland cement is
crystalline due to slower cooling. The difference between fly ash and Portland cement is the
relative quality of the different compounds. Portland cement is rich in lime (CaO) while fly
ash has low. Fly ash is high in reactive silicates while Portland cement has smaller amount.
16
Fly ash containing higher levels of calcium oxide became available due to the use of coal and
lignite containing calcium compounds in their incombustible fraction. Most such coals in the
United States are sub-bituminous and lignitic. Concurrent with this increased availability of
fly ash, extensive research in the United States, Canada and elsewhere has led to better
understanding of the chemicals reactions involved and improved the technology to
economically use the large quantities of fly ash now available to the concrete industries (ACI,
SP-79).
2.2.4.2 Hydration mechanisms of fly ash
The principal product of the reactions of fly ash with calcium hydroxide and alkali in
concrete is the same as that of the hydration of Portland cement, calcium silicate hydrate(C-
S-H). The morphology of the Class F fly ash reaction product is suggested to be more gel-like
and denser than that from Portland cement (Idorn, 1983). The reaction of fly ash depends
largely upon breakdown and dissolution of the glassy structure by the hydroxide ions and the
heat generated during the early hydration of the Portland cement fraction. The reaction of the
fly ash continues to consume calcium hydroxide to form additional C-S-H as long as calcium
hydroxide is present in the pore fluid of the cement paste. Regourd (1983) indicated that a
very small, immediate chemical reaction also takes place when fly ash is mixed with water,
preferentially releasing calcium and aluminumions to solution. This reaction is limited,
however, until additional alkali or calcium hydroxide or sulfates are available for reaction.
The amount of heat evolved as a consequence of the reactions in concrete is usually reduced
when fly ash is used together with Portland cement in the concrete. The rate of early heat
evolution is reduced in these cases and the time of maximum rate of heat evolution is retarded
(Mehta, 1983; Wei, Grutzeck, and Roy, 1984). When the quantity of Portland cement per unit
volume of concrete is kept constant, the heat evolved is increased by fly ash addition (Mehta,
1983). Idorn (1984) has suggested that, in general, fly ash reaction with Portland cement in
modern concrete is a two-stage reaction. Initially, and during the early curing the primary
reaction is with alkali hydroxides, and subsequently the main reaction is with calcium
hydroxide. This phase distinction is not apparent when research is conducted at room
temperature; at room temperature the slower calcium-hydroxide activation prevails and the
early alkali activation is minimized. As was shown to be the case for Portland cement by
Verbeck (1960), the pozzolanic reaction of fly ashes with lime and water follows Arrhenius’
law for the interdependence of temperatures and the rates of reaction. An increase in
temperature, causes a more than proportionate increase in the reaction rate. Clarifying the
17
basic principles of fly ash reaction makes it possible to identify the primary factors which, in
practice, will influence the effectiveness of the use of fly ash in concrete. These factors
include; (a) the chemical and phase composition of the fly ash and of the Portland cement; (b)
the alkali-hydroxide concentration of the reaction system; (c) the morphology of the fly ash
particles; (d) the fineness of the fly ash and of the Portland cement; (e) the development of
heat during the early phases of the hydration process; and (f) the reduction in mixing water
requirements when using fly ash. Variations in chemical composition and reactivity of fly ash
affect early stage properties and the rheology of concrete (Roy, Skalny, and Diamond, 1982).
It is difficult to predict concrete performance through characterization of fly ashes by
themselves. Fly ash accept-ability with regard to workability, strength characteristics, and
durability must be investigated through trial mixtures of concrete containing the fly ash.
Fly ash used in concrete for reasons including economics, improvements and reduction in
temperature rise in fresh concrete, workability and contribution to durability and strength in
hardened concrete. Fly ash makes efficient use of the products of the hydration of Portland
cement. Solution of calcium and alkali-hydroxide, which exist in the pore structure of the
cement paste and the heat, generated by hydration of Portland cement, an important factor in
initiating the reaction of the fly ash. When fly ash concrete is properly used, fly ash reaction
products help fill in the spaces between hydrating cement particles in the cement paste
fraction of the concrete, thus lowering its permeability to water and aggressive chemicals
(Monmohan and Mehta, 1981). The slower reaction rate of many fly ashes is a real help in
limiting the amount of early temperature rise in massive structures. Using fly ash in concrete
saves energy by reducing the amount of Portland cement required to achieve the desired
concrete properties.
2.3 Factors influencing the strength of concrete
Of the various strengths of concrete the compressive strength received a large amount of
attention because the concrete is primarily meant to withstand compressive stresses. The
strength of concrete results from: (i) the strength of the mortar; (ii) the bond between the
mortar and the coarse aggregate; and (iii) the strength of the coarse aggregate particles. For a
given cement and acceptable aggregate, the strength that may be developed by a workable,
properly placed mixture of cement, aggregates, and water (under the same mixing curing, and
testing conditions) is influenced by the:
18
(a) Ratio of cement to mixing water.
(b) Ratio of cement to aggregate.
(c) Maximum size of aggregate
(d) Grading, surface texture, shape, strength, and stiffness of aggregate particles. (Neville,
1995; Shetty, 1988; Gambhir, 1993; and Rashid and Mansur, 2009).
Previous studies on the influences of major parameters of ingredients of concrete on its
compressive strength are presented in the following articles.
2.3.1 The Influence of water/cement ratio on the strength of concrete
The strength of concrete primarily depends upon the strength of cement paste. Whereas the
strength of cement paste increases with cement content and decreases with air and water
content. When concrete is fully compacted, its strength is taken to be inversely proportional
to the water/cement ratio. This relation was preceded by a so-called `law’ but really a rule,
established by Duff Abrams and is expressed by the Eq. (1.1)
From an understanding of the factors responsible for the strength of the hydrated cement
paste and the effect of increasing water/cement ratio on porosity at a given degree of cement
hydration, the water/cement ratio-strength relationship in concrete can easily be explained as
the natural consequence of a progressive weakening of the matrix caused by increasing
porosity with increase in the water/cement ratio. This explanation, however, does not
consider the influence of the water/cement ratio on the strength of the transition zone. In low-
and medium-strength concrete made with normal aggregate, both the transition zone porosity
and the matrix porosity determine the strength, and a direct relation between the
water/cement ratio and the concrete strength holds. This seems no longer to be the case in
high-strength (i.e. very low water/cement ratio) concretes. For water/cement ratios under 0.3,
disproportionately high increases in the compressive strength can be achieved for very small
reductions in water/cement ratio. The phenomenon is attributed mainly to a significant
improvement in the strength of the transition zone at very low water/cement ratios. One of the
explanations is that the size of calcium hydroxide crystals becomes smaller with decreasing
water/cement ratios (Mehta, 2001).
Since the relationship between the water/cement ratio and compressive strength for Portland
cement concrete cannot be described by any single curve, it would seem appropriate that a
19
harmonized term relating to the mass ratio of water to all cementitious materials could be
established. In lieu of terms such as water/cement ratio, water/cement plus pozzolan ratio,
and water/cementitious materials ratio, more emphasis may be given on the term water/binder
ratio. The practice of including pozzolans and other hydraulic materials when calculating the
water/cement ratio is a long accepted industry practice. Understanding that a describable
relationship exists between water/binder ratio and compressive strength for a given type of
binding system is what matters, not the magnitude of strength correlated to any one binding
system. As Fig. 2.1 demonstrates, given the many different types and feasible combinations
of cementitious materials for use in the production of hydraulic cement concrete, it would
seem more appropriate to envision the relationship between water/binder ratio and strength in
terms of a strength envelope rather than a single curve. A similar relationship was suggested
by Aïtcin (1998). Whether a material is classified as hydraulic or pozzolanic when first
combined is irrelevant compared to the manner in which the materials interact, what they
ultimately become, and the manner in which they become.
Fig. 2.1 Strength versus various combinations of cements and pozzolans (Caldarone, 2009)
2.3.2 The Influence of aggregate/cement ratio on the compressive strength
Aggregates are important constituents in concrete. They reduce shrinkage of concrete.
Earlier, aggregate were considered as chemically inert materials but now it has been
recognized that some of the aggregates are chemically active and also that certain aggregates
20
exhibit chemical bond at the interface of aggregate and past. The mere fact that the aggregate
occupy 70 to 80 percent of the volume of concrete, their impact on various characteristics and
properties of concrete is undoubtedly considerable (Shetty, 1988). To know more about the
concrete it is very essential that one should know more about the aggregate which constitute
major volume in concrete. Without the study of the aggregate in depth and range, the study of
the concrete is incomplete. Cement is the only factor made standard compound in concrete.
Other ingredients, namely, water and aggregate are natural materials and can vary to any
extent in many of their properties. The depth and range of studies that are required to be made
in respect of aggregate, to understand their widely varying effects and influence on the
properties of concrete can not be underrated.
As long as the workability of concrete is maintained at a satisfactory level, the compressive
strength of concrete had been found to increase, with increase in aggregate/cement ratio, the
water/cement ratio being held constant (Neville, 1995 and Bureau of Indian Standards, 1990)
(Fig. 2.2).
Fig. 2.2 Effect of aggregate/cement ratio on the strength of concrete (Neville, 1995)
However, in high strength concrete mixes of lower workability or in such situations where
due to increase in aggregate/cement ratio the workability is reduced to such an extent that
concrete cannot be properly placed and thoroughly compacted, the above is not true. In high
21
strength mixes of low workability, a decrease in aggregate/cement ratio may result in small
increase in compressive strength, provided the water content in the mix is also reduced
proportionately (Bureau of Indian Standards, 1990) (Fig. 2.3). A higher aggregate content
would lead to lower shrinkage and lower bleeding, and therefore to less damage to the bond
between the aggregate and the cement paste; likewise, the thermal changes caused by the heat
of hydration of cement would be smaller. The most likely explanation, however, lies in the
fact that the total water content per cubic meter of concrete is lower in a leaner mix than in a
rich one. As a result, in a leaner mix, the voids form a smaller fraction of the total volume of
concrete, and it is these voids that have an adverse effect on strength (Neville, 1995).
Fig. 2.3 Typical relation between concrete strength and aggregate/cement ratio for various compacting factors (Bureau of Indian Standards, 1990)
2.3.3 Influence of the coarse aggregate/fine aggregate ratio on concrete strength
A reduction in the void content of the coarse aggregate by better packing means that the
amount of mortar can be reduced and hence sand and cement. Thus the well graded coarse
aggregate to sand ratio is increased and although the overall mix may be leaner the mortar
may be richer, and by virtue of reduction in water/cement ratio which may thereby be
permitted, the strength of concrete may be increased ( Duggal, 2008).
2.3.4 Influence of maximum size of coarse aggregate on the strength of concrete.
At one time it was thought that the use of larger size aggregate leads to higher strength. This
was due to the fact that the larger the aggregate the lower the total surface area and, therefore,
the lower is the requirement of water for the given workability. For this reason, a lower water
22
/cement ratio can be used which will results in higher strength. However, later it was found
that the use of larger size aggregate did not contribute to higher strength as expected from the
theoretical considerations ( Kaoser, 2006).
The larger maximum size aggregate gives lower surface area for developments of gel bonds,
which is responsible for the lower strength of the concrete. Secondly bigger aggregate size
causes more heterogeneity in the concrete, which will prevent the uniform distribution of load
when stressed. When larger size aggregate is used, due to internal bleeding, the transition
zone will become much weaker due to the development of micro-cracks, which result in
lower compressive strength. Generally, high strength concrete or rich concrete is adversely
affected by the use of large size aggregate. But in lean mix or weaker concrete the influence
of size of the aggregate gets reduced. It is interesting to note that in lean mixes larger
aggregate gives higher strength while in rich mixes it is the smaller aggregate, which yields
higher strength (Shetty, 1988; Kaoser, 2006; Abebe Dinku, 2005; and Duggal, 2008). The
influence of maximum size of aggregate on compressive strength of concrete with different
cement content is shown in Fig. 1.2 and that with different water/cement ration is shown in
Fig. 2.4
Fig. 2.4 Influence of maximum size of aggregate on concrete strength (Duggal, 2008)
A change in the maximum size of well-graded coarse aggregate of a given mineralogy can
have two opposing effects on the strength of concrete. With the same cement content and
consistency, concrete mixtures containing larger aggregate particles require less mixing water
23
than those containing smaller aggregate. On the contrary, larger aggregates tend to form
weaker transition zones containing more micro cracks. The net effect will vary with the
water/cement ratio of the concrete and the applied stress. Cordon, (1963) showed that in the
No.4 mesh to 3 in. (5 mm to 75 mm) range the effect of increasing maximum aggregate size
on the 28-day compressive strengths of the concrete was more pronounced with a high-
strength (0.4 water/cement ratio) and a moderate-strength (0.55 water/cement ratio) concrete
than with a low-strength concrete (0.7 water/cement ratio). This is because at low
water/cement ratios the reduced porosity of the transition zone also begins to play an
important role in concrete strength. Furthermore, since the transition zone characteristics
appear to affect the tensile strength of concrete more than the compressive strength, it is to be
expected that in a given concrete mixture, at a constant water/cement ratio, the tensile-
compressive strength ratio would increase with the decreasing size of coarse aggregate
(Mehta, 2000).
2.3.5 Influence of replacing cement by fly ash on concrete strength
The use of fly ash in limited amounts as a replacement for cement or as an addition to cement
requires a little more water for the same slump because of fineness of the fly ash. It is
generally agreed that the use of fly ash, particularly as an admixture rather than as a
replacement of cement, reduces, segregation and bleeding. If the sand is coarse the addition
of fly ash produces beneficial results; for fine sands, its addition may increase the water
requirement for a given workability. Since the puzzolanic action is very slow, an addition of
fly ash up to 30 per cent may result in lower strength at 7 and 28 days, but may be about
equal at 3 months and may further increase at ages greater than 3 months provided curing is
continued (Duggal, 2008).
Properties of fly ash, contributes strength and improve durability of concrete when used with
Portland cement. Chandaprasirt, Jaturapitakkul, and Sinsiri, (2005) studied on concrete with
fly ash as the partial replacement of Portland cement at 0%, 20%, and 40% by weight. The
water to binder ratio of 0.35 was used for all the blended cement past mixes. Compressive
strength of blended cement pastes decreased with an increase in the replacement of fly ash.
When fly ash was classified to a reasonably fly ash, the rate of compressive strength gain of
the blended cement pastes was significantly improved. The compressive strength of the
classified fly ash CFA paste at 90 days were significantly higher than those of original fly
ash (OFA) paste and were only slightly lower than that of the Portland cement (PC) paste at
24
the same age. The smaller and spherical fly ash particles filled the voids or airspaces and
increased the density. The smaller particles size of fly ash with a higher surface area and
glassy phase content also improved the pozzolanic reaction. Therefore, the CFA made the
blended cement paste more homogeneous and denser as well as having a higher pozzalonic
reaction than the one containing the original fly ash, and this resulted in an increase in the
compressive strength
Kazberuk and Lelusz, (2007)reported that the addition of fly has no significant effect on
specific gravity and water absorbability of concrete but the addition reduces the capillary
suction of water. The test results show that finally all mixes, containing fly ash, were able to
develop a higher flexural strength than the control mixes (FA/C = 0). The results obtained
show that the fly ash has a beneficial effect on compressive strength of all cements tested.
Although the rate of strength increase of fly ash concrete is slower and sustains for longer
periods, the concretes containing fly ash are capable of developing a higher strength than
Portland cement concrete as well as the blast furnace cement concrete. After 180 days of
storage the concretes containing 20% of fly ash, related to cement mass, gained a
compressive strength about 25% higher than the concrete without addition of fly ash, for all
types of cement. Statistical methods can be used to investigate the selected range of binders
combinations (cement and fly ash) influence on chosen performance characteristics of
concrete. Elaborated and verified statistical models can serves a tool for estimating the
compressive strength development of concrete according to fly ash content (in the range
tested) and time of curing as well to identify the optimum binder content. The knowledge of
basic properties of fly ash is fundamental to their effective usage in building industry.
25
CHAPTER 3
EXPREMENTAL INVESTIGATIONS
3.1 General
In this study an experimental program was carried out by making and crushing 297 nos. of
cylindrical concrete specimens made with brick aggregate. Five major parameters were
considered such as content cement content, water/cement (W/C) ratio, coarse aggregate/fine
aggregate (CA/FA) ratio, maximum size of coarse aggregate and percent replacement of
cement with fly ash. The experimental program may be divided into three phases. The first
phase consisted of determining the physical properties of constituent materials like cement,
fine aggregate, coarse aggregate, water and fly ash. The second phase is involved casting of
specimens (cylinders) in the laboratory and curing them for specified days. The third phase
comprises of testing specimens and to record the crushing load values.
3.2 Test program
An extensive experimental program has been designed to study the influences of the four
major parameters of concrete on its compressive strength. The parameters considered are-
(i) Content of cement in concrete
(ii) Water to cement (W/C) ratio of concrete
(iii) Maximum size of coarse aggregate used for concrete and
(iv) Coarse aggregate/fine aggregate (CA/FA) ratio of the concrete.
Besides, the effect of replacing (partially) cement by fly ash on the strength of concrete has
also been considered for second phase of experimental study. For the first phase of study a
total of nine mix ratios (M-1 through M-9) has been considered (Table 3.1) for the two
parameters such as the cement content and the CA/FA ratio of concrete.
For each of the above mentioned nine concrete mixes three water/cement ratios (0.40, 0.50,
and 0.60) by weight and three maximum sizes (25.0 mm, 19.0 mm, 12.5mm) of coarse
aggregate have been considered. Therefore, a total of 9×3×3 or 81 mixes of concrete and
hence a total of 81×3 or 243 nos. of cylindrical specimens are planned to be cast and tested
for compressive strength at the age of 28 days.
26
Table 3.1 Mix ratios and related variables for the first phase of study
Mix
designation
Concrete mix ratio
(by volume) Cement
aggregateTotal ratio (by vol.) FA
CA ratio (by
vol.)
M-1 1 : 2 : 4 6.0 2.0
M-2 1 : 1.5 : 3 4.5 2.0
M-3 1 : 1 : 2 3.0 2.0
M-4 1 : 2.4 : 3.6 6.0 1.5
M-5 1 : 1.8 : 2.7 4.5 1.5
M-6 1 : 1.2 : 1.8 3.0 1.5
M-7 1 : 1.714 : 4.286 6.0 2.5
M-8 1 : 1.286 : 3.214 4.5 2.5
M-9 1 : 0.857 : 2.143 3.0 2.5
For the second phase a total of eighteen mixes (MF-1 through MF-18) have been considered
to study the effect of replacing (partially) cement (ordinary Portland cement, OPC) by equal
weight of fly ash on the compressive strength of brick aggregate concrete (Table 3.2). In this
phase a total of 18×3 or 54 nos. of cylindrical specimens have been planned to be cast and
tested.
The casting and testing of all specimens will be done following the ASTM specifications.
Test data will be analyzed with a view to study the influence of various parameters
considered in achieving higher strength concrete.
27
Table 3.2 Mixes of the second phase of experimental study
Mix designation % replacement of OPC by fly ash (by
weight)
Age of concrete
(day)
MF-1
0.0
3
MF-2 7
MF-3 14
MF-4 28
MF-5 60
MF-6 90
MF-7
10.0
3
MF-8 7
MF-9 14
MF-10 28
MF-11 60
MF-12 90
MF-13
20.0
3
MF-14 7
MF-15 14
MF-16 28
MF-17 60
MF-18 90
NB: For all of the above mixes the mix ratio, the maximum size of coarse aggregate, and the water/cement ratio considered are 1:1.5:3 (by vol.), 19.0 mm, and 0.50 respectively.
3.3 Properties of ingredients used for making concrete
3.3.1 Cement
Commercially purchased locally produced Holcim (Red) brand cement (Ordinary Portland
Cement) was used in this experiment. Properties of cement were determined first. Normal
consistency and setting times were determined by using Vicat apparatus and test methods
conform to the standard requirements of ASTM specifications C187 and C191 respectively.
28
The compressive strength of the cement mortar was measured and test methods conform to
the ASTM standard requirements of specification C109. The properties of cement used for
the experiment ensured satisfactory properties according to ASTM C150 as a binding
material for concrete. Properties of cement used in the experiment are shown in Table 3.3.
Table 3.3 Properties of the cement used in the experiment
Property of cement Test value
Normal consistency 28%
Initial setting time 3 hr. 17 min.
Final setting time 5 hr. 45 min.
Compressive strength (7 days) 29.19 MPa
Compressive strength (28 days) 36 .52 MPa
Ordinary Portland cement is used most commonly and widespread at present time. The origin
of the name “Portland” cement was usually attributed to Joseph Aspdin, a brick mason in
England. The common properties of OPC are as follow:
i) Finely powdered substance
ii) Gray to brownish gray
iii) Composed of crystalline minerals
iv) Particle size ranges from 0.50 micron to 80 micron in diameter
v) Specific gravity ranges from 3.12 to 3.16
The oxide compositions and principal components in Portland cement are given in Table 3.4
and Table 3.5 (ASTM C150-98) respectively.
Table 3.4 Oxide Composition of Ordinary Portland cement
Oxide composition % by weight
Calcium oxide, CaO 59-65
Silicon di-oxide, SiO2 19-25
Aluminium tri-oxide, Al2O3 5-9
Ferric oxide, Fe2O3 1-5
Magnesium oxide, MgO 1-4
Sulfur tri-oxide, SO3 1-5
29
Table 3.5 Principal Components of Ordinary Portland cement
Name of component Symbol Abbreviation % by weight
Tricalcium silicate 3CaO.SiO2 C3S 46% minimum
Dicalcium silicate 2CaO.SiO2 C2S 29% minimum
Tricalcium aluminate 3CaO.Al2O3 C3A 7%-10%% minimum
Tetracalcium alumino ferrite 4CaO. Al2O3.Fe2O3 C4AF 15% minimum
3.3.2 Coarse and fine aggregates
Although aggregates are most commonly known to be inert filler in concrete, the different
properties of aggregate have a large impact on the strength, durability, workability, and
economy of concrete. These different properties of aggregate allow designers and contractors
the most flexibility to meet their design and construction requirements
(www.engr.psu.edu/ce/.../concrete/.../Aggregate/Aggregatesmain.htm).
Locally available coarse and fine aggregate were used in this study. Standard test method
ASTM C136 was followed for sieve analysis of fine and coarse aggregate. For coarse
aggregate, the sieve analysis was performed through standard sieve sizes of 37.5, 19.0, 9.5,
4.75, 2.36, 1.18, 0.60, 0.30, and 0.15 mm by a mechanical sieve shaker for 15 minutes. On
the other hand, standard sieve sizes of #4, #8, #16, #30, #50 and #100 were used to analyze
the fineness of sand. Absorption of coarse aggregate was determined according to standard
test method ASTM C127 whereas for fine aggregates, standard test method ASTM C128 was
followed. The Properties of fine aggregate and three size coarse aggregates used in the
laboratory experiment are shown in Table 3.6 and Table 3.7 respectively. Photographs of
coarse and fine aggregates are presented in Figs. 3.1, 3.2 respectively.
Table 3.6 Properties of fine aggregates used
Property of aggregate Test value
Fineness modulus 2.48
Water absorption (%) 2.0
Unit weight ( Kg /m3) 1492.36
30
Table 3.7 Properties of coarse aggregates used
Property of aggregates
Test value of
25.0 mm down
graded brick
aggregate
19.0 mm down
graded brick
aggregate
12.5 mm down
graded brick
aggregate
Fineness modulus 7.073 6.782 6.258
Water absorption (%) 11.4 11.4 11.4
Unit weight ( Kg /m3) 1075.66 1091.87 1100.88
(a) 25 mm down graded (b) 19.0 mm down graded
(c) 12.5 mm down graded
Fig. 3.2 Fine aggregate used
3.3.3 Water
Combining water with a cementitious material forms a cement paste by the process of
hydration. The product of hydration and cement paste glues the aggregate together, fills voids
within it, and allows it to flow more freely. Less water in the cement paste will yield a
stronger, more durable concrete, more water will give a free-flowing concrete with a higher
slump. Impure water used to make concrete can cause problems when setting or in causing
premature failure of the structure. Hydration involves many different reactions, often
Fig. 3.1 Coarse aggregate used in the study
31
occurring at the same time. As the reactions proceed, the products of the cement hydration
process gradually bond together the individual sand and gravel particles, and other
components of the concrete, to form a solid mass. Water is the most important and least
expensive ingredient of concrete. A part of mixing water is utilized in the hydration of
cement to form the binding matrix in which the inert aggregate are held suspension until the
matrix has hardened. Remaining water serves as a lubricant between the fine and coarse
aggregate and makes constant workability. The strength and durability of concrete is reduced
due to the presence of impurities in the mixing water. Water used in mixing concrete shall be
clean and free from injurious amount of oils, alkalis, salts, organic materials or other
substances that may be deleterious to concrete. In this study drinking water have been used in
mixing of concrete which is supplied from deep tube well of DUET and is known to have no
unusual impurities.
3.3.4 Fly ash
Fly ash or pulverized fuel ash is the residue from the combustion of pulverized coal collected
by the mechanical or electrostatic separator from the fuel gases of thermal power plants. Its
composition varies with the type of fuel burnt, load on boiler. Types of fly ash consist mainly
of spherical glassy partials ranging from 1 to 150 micro meters in diameter which pass
through a 45 micro meter sieve. It has a specific surface of about 3500 to 5000 square
centimeter per gram. It is finer than Portland cement. Fly ash may be used in concrete either
as an admixture or in part replacement of cement. Fly ash contains very finer particles this is
why to consider it for making concrete. It is finer than Portland cement particle so this
particle can minimize the voids among cement particles as a result dense concrete is found
and compressive strength is more. Some test results as provided by the supplier (local cement
manufacturing company, Seven Rings Cement) which are shown in Table 3.8.
Table 3.8 Properties of fly ash used (as provided by the supplier)
Property of fly ash Test value
Fineness 2808 cm2/gm
Residue 24.75 %
Moisture 0.23 %
Loss on ignition 3.6 %
32
3.4 Preparation of test specimens
3.4.1 Preparation of coarse aggregate
In Bangladesh, crushed brick, an indigenous material, is used in parallel to stone aggregate as
coarse aggregates because of scarcity of natural stone. Locally produced brick can attain a
compressive strength as high as 52 MPa, with the most commonly found ones ranging from
17 to 24 MPa (http:// www.saifulamin.info/publication/conference_proceeding/c12.pdf).
Investigation from previous research reveals that specific gravity and unit weight of brick
chips are much lower and absorption capacity is much higher than the natural stone
aggregates (Rashid, Hossain, and Islam, (2009); and Bazaz, Khayati, Akrami, 2006).
In this study 1000 nos. of Gas burnt first class bricks manufactured by a local company
(Unique Ceramic Bricks) were collected for making coarse aggregate (usually known as
khoa). Representative samples of collected bricks were then tested in the laboratory for their
crushing strength and the average compressive strength was found as 47.12 MPa. The
remaining bricks were then broken manually in three different sizes namely 25.0 mm down-
graded, 19.0 mm down-graded, and 12.0 mm down-graded (Fig. 3.1). At first 25.0 mm down-
graded coarse aggregates were prepared from 300 pieces of brick. These aggregates were
passed through 25.0 mm opening sieve and then #4 sieve. The portion of the broken bricks
which were passed through 25.0 mm sieve and were retained on #4 sieve were collected and
considered as 25.0 mm downgraded coarse aggregates. Following the same procedure, 19.0
mm and 12.5 mm down-graded aggregates (khoa) were prepared from broken bricks by using
19.0 mm & #4 sieves and 12.5 mm & #4 sieves respectively.
3.4.2 Casting cylindrical specimens
Required numbers of steel moulds each of 6×12 inches size were cleaned using wire brush
and then their joints were tightened by nut-bolts. These cleaned moulds were placed on firm
and leveled floor on concrete laboratory. Lubricating oil (Mobil) was used to smear the
bottom and inside of the mold for its easy removal after hardening of concrete. Fresh concrete
was prepared as per designed mix in a drum type mixture machine. Immediately after
unloading from mixture machine, the fresh concrete was placed in the mould in three layers
and was compacted each layer of concrete by using nozzle type vibrator machine as shown in
Fig. 3.3 (ACI 309.1R-93, 1994). The fresh concrete the specimens molds were kept in the
laboratory without any disturbance undisturbed for 24 hours in such a way as to prevent
moisture loss the specimens within room temperature.
33
Fig. 3.3 Compaction of fresh concrete using vibrator
3.4.3 Curing of specimens
Curing can be defined as the process of maintaining a satisfactory moisture content and
favorable temperature in concrete during the period immediately following placement, so that
hydration of cement may continue until the desired properties are developed to a sufficient
degree to meet the requirement of service. Curing in an important process after casting of
concrete as it helps in gaining strength rapidly. Fresh concrete gains strength the most rapidly
during the first few days and weeks. Structural design is generally based on the 28-days
strength, about 70 percent of which is reached at the end of the first week after placing of
concrete. The final concrete strength depends greatly on the conditions of moisture and
temperature during this initial period. Curing is essential in the production of good quality
and durable concrete. It is given a place of increasing importance as the demand for high
quality concrete is increasing. There are several methods of curing such as water curing,
membrane curing, application of heat, and miscellaneous. Water curing is the best method of
curing as it satisfies the entire requirement namely, promotion of hydration, and elimination
of shrinkage and absorption of the heat of hydration. In this study the test specimens were
removed from the moulds after 24 hours and were shifted carefully to the place of curing.
Cylinder specimens were then submerged into water tank and kept undisturbed there as
shown in Fig. 3.4 for the curing period designed.
Fig. 3.4 Curing of concrete specimens
34
3.5 Testing of cylindrical specimens
3.5.1 Preparing the test specimens
The test cylinders were collected from curing tank before 24 hours of testing and kept in air
dry condition in the laboratory. Both the ends of cylinders were grinded by grinding machine
in order to make the end surfaces smooth and leveled (Fig. 3.5). Some concrete technologists
prefer to form or grind specimen ends to ASTM C39 tolerance when compressive strengths
are greater than 10,000 psi (ACI committee 232, 2001). Then the measurements for diameter
of each specimen were taken using slide calipers. Average of three measurements those at
top, middle, and bottom were considered in determining the diameter of each of the test
specimens.
(a) Specimen under grinding
(b) Grinded specimen
Fig. 3.5 Grinding of concrete cylinder
3.5.2 Testing of the Specimens
Concrete cylinders were tested in the lab using the 1000 kN capacity Universal Testing
Machine following the ASTM C39 specifications. At first the test cylinder was placed on the
machine’s base platen keeping it vertical and centered on the plate. Then load was applied on
the top surface of the specimen [Fig. 3.6 (a)]. This load was increased gradually until the
specimens failed [Fig. 3.6 (b)]. The crushing load was then recorded.
(a) Concrete cylindrical specimen under test
Fig.3.6
3.5.3 Test results
The crushing load of each of the test specimens was divided the average cross sectional area
of respective cylindrical specimen and was recorded as the compressive strength of that
concrete. These crushing strengths of all of the concretes along with their
parameters are presented in Tables 3.9 and 3.10
Table 3.9 Concrete mix variables and their compressive strengths
Mix designation
(Mix ratio) W/C
M-1
(1 : 2 : 4)
M-2
(1 : 1.5 : 3)
35
Concrete cylindrical specimen under test
(b) Failure of specimen
3.6 Testing of concrete cylindrical specimen
The crushing load of each of the test specimens was divided the average cross sectional area
of respective cylindrical specimen and was recorded as the compressive strength of that
concrete. These crushing strengths of all of the concretes along with their
presented in Tables 3.9 and 3.10.
Table 3.9 Concrete mix variables and their compressive strengths
W/C ratio Maximum size of CA
(mm)
Concrete compressive
strength (MPa)
0.40
25.0
19.0
12.5
0.50
25.0
19.0
12.5
0.60
25.0
19.0
12.5
0.40
25.0
19.0
12.5
(b) Failure of specimen
The crushing load of each of the test specimens was divided the average cross sectional area
of respective cylindrical specimen and was recorded as the compressive strength of that
concrete. These crushing strengths of all of the concretes along with their respective
Concrete compressive
strength (MPa)
28.43
36.64
29.83
29.52
28.57
28.49
33.88
24.57
28.48
33.74
36.62
35.31
36
Mix designation
(Mix ratio) W/C ratio
Maximum size of
CA (mm)
Concrete compressive
strength (MPa)
M-2
(1 : 1.5 : 3)
0.50
25.0 30.30
19.0 32.69
12.5 32.66
0.60
25.0 17.89
19.0 29.97
12.5 29.31
M-3
(1 : 1 : 2)
0.40
25.0 34.68
19.0 35.29
12.5 35.57
0.50
25.0 33.66
19.0 36.56
12.5 37.97
0.60
25.0 25.66
19.0 26.70
12.5 28.96
M-4
(1: 2.4 : 3.6)
0.40
25.0 27.31
19.0 32.98
12.5 26.81
0.50
25.0 24.91
19.0 25.11
12.5 23.67
0.60
25.0 19.57
19.0 21.86
12.5 21.60
M-5
(1: 1.8 : 2.7)
0.40
25.0 34.72
19.0 28.04
12.5 34.35
0.50
25.0 25.19
19.0 29.86
12.5 29.13
37
Mix designation
(Mix ratio) W/C ratio
Maximum size of
CA (mm)
Concrete compressive
strength (MPa)
M-5
(1: 1.8 : 2.7)
0.60
25.0 23.39
19.0 21.16
12.5 23.11
M-6
(1: 1.2 : 1.8)
0.40
25.0 37.74
19.0 37.37
12.5 34.44
0.50
25.0 28.46
19.0 34.26
12.5 32.93
0.60
25.0 22.09
19.0 20.32
12.5 19.72
M-7
(1: 1.714 : 4.286)
0.40
25.0 28.21
19.0 28.36
12.5 26.16
0.50
25.0 17.28
19.0 21.35
12.5 21.79
0.60
25.0 17.38
19.0 16.03
12.5 14.93
M-8
(1: 1.286 : 3.214)
0.40
25.0 32.44
19.0 32.74
12.5 29.50
0.50
25.0 20.62
19.0 25.26
12.5 25.39
0.60
25.0 19.65
19.0 19.19
12.5 17.45
38
Mix designation
(Mix ratio) W/C ratio
Maximum size of
CA (mm)
Concrete compressive
strength (MPa)
M-9
(1: 0.857 : 2.143)
0.40
25.0 31.7
19.0 27.05
12.5 34.10
0.50
25.0 30.68
19.0 26.74
12.5 27.93
0.60
25.0 19.54
19.0 23.34
12.5 18.69
39
Table 3.10 Fly ash concrete mix variables and their compressive strengths
Mix
designation % replacement of OPC
by fly ash (by weight) Age of concrete
(day) Compressive
strength (MPa)
MF-1
0.0
3 12.04
MF-2 7 20.67
MF-3 14 24.54
MF-4 28 28.24
MF-5 60 33.94
MF-6 90 35.59
MF-7
10.0
3 9.347
MF-8 7 17.22
MF-9 14 21.14
MF-10 28 25.55
MF-11 60 31.40
MF-12 90 34.48
MF-13
20.0
3 7.236
MF-14 7 15.55
MF-15 14 17.25
MF-16 28 25.43
MF-17 60 30.67
MF-18 90 33.00
NB: For all of the above mixes the mix ratio, the maximum size of coarse aggregate,
and the water/cement ratio considered are 1:1.5:3 (by vol.), 19.0 mm, and 0.50
respectively.
40
CHAPTER 4
ANALYSIS AND DISCUSSIONS ON TEST RESULTS
4.1 General
In most structural applications concrete is employed primarily to resist compression stresses.
In those cases where strength in tension or in shear is primary importance compressive
strength is frequently used as a measure of these properties. Therefore, the concrete making
properties of various ingredients of mix are usually measured in terms of the compressive
strength. Compressive strength is also used as a qualitative measurer of other properties of
hardened concrete (ACI 318, 1989). The compressive strength of concrete is generally
determined by testing cylinders in laboratory or field or cores drilled from hardened concrete
at site or from the non-destructive testing of the specimen or actual structures. Strength of
concrete is its resistance to rupture. It may be measured in a number of ways as, strength in
compression, in tension, in shear or in flexure. All these indicate strength reference to a
particular method of testing. Test results on the compressive strength of concrete as obtained
in the previous chapter are analyzed considering various parameters. The detailed discussions
on the influence of parameters on concrete strength are presented in this chapter.
4.2 Concrete strengths obtained from test data
The crushing strengths of test concretes were obtained by dividing their crushing load
capacity with the respective cross sectional areas and are given in Tables 3.9 and 3.10. These
data are considered here as the basic information of the respective concretes which have been
influenced by the parameters considered in this study. These data have been analyzed and
discussed in the following articles.
4.3 Influence of various parameters on concrete strength
The parameters considered in this study are: (i) Water/cement (W/C) ratio, (ii) Total
aggregate/cement (A/C) ratio, (iii) Coarse aggregate/fine aggregate (CA/FA) ratio, (iv)
Maximum size of coarse aggregate, and (v) Replacement of cement by equal weight of fly
ash (FA). The influences of these variables on the cylinder compressive strength of concrete
are reported and discussed in the followings.
41
4.3.1 Influence of water/cement ratio on compressive strength
Figs. 4.1 (a), (b) and (c) show the variations of the experimental values of concrete compressive strength with the variation of water to cement (W/C) ratio. Thesis nine graphs are shown together in Appendix-B (Fig. B.1)
Fig. 4.1(a) Influence of water/cement ratio on compressive strength of concrete with
A/C = 3.0
10
15
20
25
30
35
40
45
0.3 0.4 0.5 0.6 0.7
Co
mp
ress
ive
stre
ngt
h,
f'c
(M
Pa
)
Water/cement ratio ( by weight )
( Max size = 12.5 mm , A/C ratio = 3.0 )
CA/FA ratio = 1.5
CA/FA ratio = 2.0
CA/FA ratio = 2.5
10
15
20
25
30
35
40
45
0.3 0.4 0.5 0.6 0.7
Co
mp
ress
ive
stre
ngt
h,
f'c
(M
Pa
)
Water/cement ratio ( by weight )
( Max size = 19 mm , A/C ratio = 3.0 )
CA/FA ratio = 1.5
CA/FA ratio = 2.0
CA/FA ratio = 2.5
10
15
20
25
30
35
40
45
0.3 0.4 0.5 0.6 0.7
Co
mp
ress
ive
stre
ngt
h,
f'c
(M
Pa
)
Water/cement ratio ( by weight )
( Max size = 25 mm , A/C ratio = 3.0 )
CA/FA ratio = 1.5
CA/FA ratio = 2.0
CA/FA ratio = 2.5
42
Fig. 4.1(b) Influence of water/cement ratio on compressive strength of concrete with
A/C = 4.5
10
15
20
25
30
35
40
45
0.3 0.4 0.5 0.6 0.7
Co
mp
ress
ive
stre
ngt
h,
f'c
(M
Pa
)
Water/cement ratio ( by weight )
( Max size = 12.5 mm , A/C ratio = 4.5 )
CA/FA ratio = 1.5
CA/FA ratio = 2.0
CA/FA ratio = 2.5
10
15
20
25
30
35
40
45
0.3 0.4 0.5 0.6 0.7
Co
mp
ress
ive s
tren
gth
, f'
c (
MP
a)
Water/cement ratio ( by weight )
( Max size = 19 mm , A/C ra tio = 4.5 )
CA/Fa ratio = 1.5
CA/FA ratio = 2.0
CA/FA ratio = 2.5
10
15
20
25
30
35
40
45
0.3 0.4 0.5 0.6 0.7
Co
mp
ress
ive s
tren
gth
, f'c
(M
Pa
)
Water/cement ratio ( by weight )
( Max size = 25 mm , A/C ratio = 4.5 )
CA/FA ratio = 1.5
CA/FA ratio = 2.0
CA/FA ratio = 2.5
43
Fig. 4.1(c) Influence of water/cement ratio on compressive strength of concrete with
A/C = 6.0
10
15
20
25
30
35
40
45
0.3 0.4 0.5 0.6 0.7
Co
mp
ress
ive s
tren
gth
, f'
c (M
Pa
)
Water/cement ra tio ( by weight )
( Max size = 12.5 mm , A/C ra tio = 6.0 )
CA/FA ratio = 1.5
CA/FA ratio = 2.0
CA/FA ratio = 2.5
10
15
20
25
30
35
40
45
0.3 0.4 0.5 0.6 0.7
Co
mp
ress
ive s
tren
gth
, f
'c (
MP
a)
Water/cement ratio ( by weight )
( Max size = 19 mm , A/C ratio = 6.0 )
CA/FA ratio = 1.5
CA/FA ratio = 2.0
CA/FA ratio = 2.5
10
15
20
25
30
35
40
45
0.3 0.4 0.5 0.6 0.7
Co
mp
ress
ive s
tren
gth
, f'c (
MP
a)
Water/cement ratio ( by weight )
( Max size = 25 mm , A /C ratio = 6.0 )
CA/FA ratio = 1.5
CA/FA ratio = 2.0
CA/FA ratio = 2.5
44
It is seen from Figs. 4.1 (a), (b) and (c) that the concrete compressive strength decreases with
the increase in W/C ratio (0.40 through 0.60) [except few cases]. For a fixed value of
aggregate to cement (A/C) ratio, an increase in W/C ratio means an increase in water
quantity. As a result the hydrated product was unable to occupy the space already filled with
water, and hence, porosity increases and strength decreases. In all cases it is expected that the
complete hydration of cement occurred because the minimum water cement ratio was 0.40 by
weight.
The average values of the compressive strengths of concretes with W/C ratio of 0.60, 0.50,
and 0.40 are found to be 22.37, 28.18, and 32.23 MPa respectively (Fig. 4.2). This indicates
an increase in compressive strengths of about 26.0% and 14.4% when the W/C ratio was
decreased from 0.60 to 0.50 and 0.50 to 0.40 respectively.
Fig. 4.2 Variation in concrete strength with the variation in water/cement ratio
The water to binder (W/B) ratio is the single most important factor influencing the strength of
concrete. In actuality, the W/B ratio is what establishes paste density. The principal factor
determining concrete strength is the density of the hydrated cement paste. As the W/B ratio
decreases, the distance between cementing materials decreases. Optimum density for a simple
cement-water paste occurs at the point of maximum particle packing with 100 percent of the
inter-particle voids filled with water. Further decreasing the W/B ratio beyond this point will
cause paste density (and measured strength) to decrease. For a given set of paste constituents,
as the W/B ratio continues to decrease, there reaches a point where paste density is
maximized. Continuing to decrease the W/B ratio further will cause paste density to decrease
and with it, strength (Caldorene, 2009).
45
4.3.2 Influence of aggregate/cement ratio on compressive strength
From the test results [Figs. 4.3(a), (b), (c)] it is found that the concrete strength decreases with the increase in aggregate to cement (A/C) ratio (except for few cases). Thesis nine graphs are shown together in Appendix-B (Fig. B.2)
Fig. 4.3(a) Influence of aggregate/cement ratio on compressive strength of concrete with W/C =0.40
10
15
20
25
30
35
40
45
2.5 3 3.5 4 4.5 5 5.5 6 6.5
Com
pre
ssiv
e
stre
ngth
, f'c
( M
pa )
A/C ratio ( by volume )
( Max CA size = 12.5 mm , W/C = 0.40 )
CA/FA=1.5
CA/FA=2.0
CA/FA=2.5
10
15
20
25
30
35
40
45
2.5 3 3.5 4 4.5 5 5.5 6 6.5
Com
pres
sive
st
reng
th, f'c
(
Mpa
)
A/C ratio ( by volume )
( Max CA size = 19.0 mm , W/C = 0.40 )
CA/FA=1.5
CA/FA=2.0
CA/FA=2.5
10
15
20
25
30
35
40
45
2.5 3 3.5 4 4.5 5 5.5 6 6.5
Com
pres
sive
st
reng
th ,
f'c
( M
pa )
A/C ratio ( by volume )
( Max CA size = 25 mm , W/C = 0.40 )
CA/FA=1.5
CA/FA= 2.0
CA/FA=2.5
46
Fig. 4.3(b) Influence of aggregate/cement ratio on compressive strength of
concrete with W/C =0.50
10
15
20
25
30
35
40
45
2.5 3 3.5 4 4.5 5 5.5 6 6.5
Com
pre
ssiv
e s
tren
gth
, f'c
(
Mp
a )
A/C ratio ( by volume )
( Max CA size = 12.50 mm , W/C = 0.50 )
CA/FA=1.5
CA/FA=2.0
CA/FA=2.5
10
15
20
25
30
35
40
45
2.5 3 3.5 4 4.5 5 5.5 6 6.5
Co
mp
ress
ive
str
ength
, f'c
(
Mp
a )
A/C ratio ( by volume )
( Max CA size = 19 mm , W/C = 0.50 )
CA/FA=1.5
CA/FA=2.0
CA/FA=2.5
10
15
20
25
30
35
40
45
2.5 3 3.5 4 4.5 5 5.5 6 6.5
Com
pre
ssiv
e s
tren
gth
, f'c
(
Mp
a )
A/C ratio ( by volume )
( Max CA size = 25.0 mm , W/C = 0.50 )
CA/FA=1.5
CA/FA=2.0
CA/FA=2.5
47
Fig. 4.3(c) Influence of aggregate/cement ratio on compressive strength of concrete
with W/C =0.60
10
15
20
25
30
35
40
45
2.5 3 3.5 4 4.5 5 5.5 6 6.5
Co
mp
ress
ive
str
eng
th, f'c
(
Mp
a )
A/C ratio ( by volume )
( Max CA size = 12.5 mm , W/C = 0.60 )
CA/FA=1.5
CA/FA=2.0
CA/FA=2.5
10
15
20
25
30
35
40
45
2.5 3 3.5 4 4.5 5 5.5 6 6.5
Co
mpre
ssiv
e s
tren
gth
, f'c
(
Mp
a )
A/C ratio ( by volume )
( Max CA size = 19.0 mm , W/C = 0.60 )
CA/FA=1.5
CA/FA=2.0
CA/FA=2.5
10
15
20
25
30
35
40
45
2.5 3 3.5 4 4.5 5 5.5 6 6.5
Co
mp
ress
ive
str
eng
th,
f 'c
( M
pa
)
A/C ratio ( by volume )
( Max CA size = 25.0 mm , W/C = 0.60 )
CA/FA=1.5
CA/FA=2.0
CA/FA=2.5
48
This might be due to the insufficient cement paste available with respect to the increased
surface area of aggregates with larger A/C ratio. This trend of decrease in /
cf is found
obvious for a W/C ratio of 0.50 [Fig. 4.3(b)] and irrespective of both coarse aggregate/fine
aggregate (CA/FA) ratio and maximum size of coarse aggregate. Duggal, (2008) also
reported the similar trend in /
cf with the variation in A/C ratio.
For a W/C ratio of 0.40, the change in /
cf with the increase in A/C ratio has been found to be
insignificant (up to A/C ratio of 4.5) and further increase in A/C ratio decreases /
cf
significantly [Fig. 4.3 (a)]. This may be due to the concrete become less workable with the
increase in aggregate surface, the W/C ratio being held constant (Bureau of Indian Standards,
1990).
For a much higher water content (W/C=0.60), the concrete's strength may either increase or
decrease with the increase in A/C ratio [Fig. 4.3(c)]. This may be due to either the lower
cement content or, increased surface area of aggregates or, both.
The average values of the compressive strengths of concretes with aggregate/cement (A/C)
ratio of 6.0, 4.5, and 3.0 are found to be 25.32, 27.77, and 29.71 MPa respectively (Fig. 4.4).
This indicates an increase in compressive strengths of about 9.7% and 7.0% when the A/C
ratio was decreased from 6.0 to 4.5 and 4.5 to 3.0 respectively.
Fig. 4.4 Variation in concrete strength with the variation in aggregate/cement ratio
49
Within the range of test variables the increase in concrete strength is found to be almost linear
with the decrease in A/C ratio (Fig. 4.3). This relation can be expressed by the Eq. (4.1).
−=′
C
Afc
463.1185.34 (4.1)
Where, /
cf = Compressive strength, and
C
A = Aggregate/cement ratio.
4.3.3 Influence of coarse aggregate/fine aggregate ratio on compressive strength
Figs. 4.5(a), (b), and (c) show the variation of /
cf with the variation of coarse aggregate/fine
aggregate (CA/FA) ratio. Thesis nine graphs are shown together in Appendix-B (Fig. B.3). It
is seen that the strength increases significantly when CA/FA ratio was varied from 1.5 to 2.0
for almost all the test concretes. Then the strength value decreases sharply for further increase
in CA/FA ratio (i.e. for CA/FA=2.5). The strength of concretes for CA/FA=2.5 are seen to be
even lower than the corresponding values for CA/FA ratio of 1.5.
Concretes with particular values of the W/C ratio and A/C ratio, have a particular amount of
cement content. The total surface area of aggregates are too high (for CA/FA ratio of 1.5) to
cover the aggregate surface with cement paste. Whereas, in case of CA/FA ratio of 2.0 the
aggregate’s total surface area is get reduced than that of earlier one and hence the cement
paste was reasonably larger to cover the aggregate surface and increased concrete strength.
However, further increase in CA/FA ratio (i.e. for CA/FA=2.5) increases the volume of voids
between CA and FA and the cement paste was not sufficient to fill those voids and thereby
reduced strength of concrete.
50
Fig. 4.5(a) Influence of coarse aggregate/fine aggregate ratio on compressive
strength of concrete with W/C =0.40
10
15
20
25
30
35
40
45
1 1.5 2 2.5 3
Co
mp
ress
ive s
tren
gth
, f'c
(M
Pa
)
CA/FA ratio
( Max size = 12.5 mm , W/C = 0.40 )
A/C ratio= 6.0
A/C ratio= 4.5
A/C ratio= 3.0
10
15
20
25
30
35
40
45
1 1.5 2 2.5 3
Co
mp
ress
ive s
tren
gth
, f'c
(M
Pa
)
CA/FA ratio
( Max size = 19.0 mm , W/C = 0.40 )
A/C ratio= 6.0
A/C ratio= 4.5
A/C ratio= 3.0
10
15
20
25
30
35
40
45
1 1.5 2 2.5 3
Co
mp
ress
ive s
tren
gth
, f
'c (
MP
a)
CA/FA ratio
( Max size = 25 mm , W/C = 0.40 )
A/C ratio= 6.0
A/C ratio= 4.5
A/C ratio= 3.0
51
Fig. 4.5(b) Influence of coarse aggregate/fine aggregate ratio on compressive strength
of concrete with W/C =0.50
10
15
20
25
30
35
40
45
1 1.5 2 2.5 3
Co
mp
ress
ive s
tren
gth
, f'c
(M
Pa
)
CA/FA ra tio
( Max size = 12.5 mm , W/C = 0.50 )
A/C ratio= 6.0
A/C ratio= 4.5
A/C ratio= 3.0
10
15
20
25
30
35
40
45
1 1.5 2 2.5 3
Co
mp
ress
ive s
tren
gth
, f'
c (
MP
a)
CA/FA ratio
( Max size = 19 mm , W/C = 0.5 )
A/C ratio= 6.0
A/C ratio= 4.5
A/C ratio= 3.0
10
15
20
25
30
35
40
45
1 1.5 2 2.5 3
Co
mp
ress
ive s
tren
gth
, f'c
(M
Pa
)
CA/FA ratio
(Max size = 25 mm , W/C = 0.50 )
A/C ratio= 6.0
A/C ratio= 4.5
A/C ratio= 3.0
52
Fig. 4.5(c) Influence of coarse aggregate/fine aggregate ratio on compressive strength of
concrete with W/C =0.60
10
15
20
25
30
35
40
45
1 1.5 2 2.5 3
Co
mp
ress
ive s
tren
gth
, f'c
(M
Pa
)
CA/FA ratio
(Max size = 12.5 mm , W/C = 0.60 )
A/C ratio= 6.0
A/C ratio= 4.5
A/C ratio= 3.0
10
15
20
25
30
35
40
45
1 1.5 2 2.5 3
Co
mp
ress
ive
stre
ngt
h,
f'c
(M
Pa
)
CA/FA ratio
( Max size = 19 mm , W/C = 0.60 )
A/C ratio= 6.0
A/C ratio= 4.5
A/C ratio= 3.0
10
15
20
25
30
35
40
45
1 1.5 2 2.5 3
Co
mp
ress
ive s
tren
gth
, f'c
(M
pa
)
CA/FA ratio
( Max size = 25 mm , W/C = 0.60 )
A/C ratio= 6.0
A/C ratio= 4.5
A/C ratio= 3.0
53
The average values of the compressive strengths of concretes with coarse aggregate-fine
aggregate (CA/FA) ratio (by volume) of 1.5, 2.0, and 2.5 are found to be 27.41, 31.18, and
24.20 MPa respectively (Fig. 4.6). From this test data, it is interesting to note that the
concrete strength is found to be the highest for a CA/FA ratio of 2.0. Whereas, either increase
or decrease of CA/FA ratio from 2.0 is found to yield a decrease in concrete strength.
Fig. 4.6 Variation in concrete strength with the variation in CA/FA ratio
4.3.4 Influence of maximum size of CA on compressive strength
Figs. 4.7(a), (b), and (c) show the influence of maximum size of coarse aggregate (CA)
studied on concrete strength /
cf . Thesis nine graphs are shown together in Appendix-B (Fig.
B.4). From this figure it may be seen that within the ranges of variables considered, the
increase in the maximum size of coarse aggregate does not have significant influence on the
concrete compressive strength. Because, with the same cement content and consistency,
concrete mixtures containing larger aggregate particles requires less mixing water than those
containing smaller aggregate On the contrary, a larger aggregate tend to form weaker
transition zones containing more micro-crack. The net effect will vary with the W/C ratio of
the concrete.
54
Fig. 4.7(a) Influence of maximum size of CA on compressive strength of concrete
with W/C =0.40
10
15
20
25
30
35
40
45
10 15 20 25 30
Co
mp
ress
ive s
tren
gth
, f'c
(
MP
a )
Maximum size of CA (mm)
( W/C = 0.40 , CA/FA = 1.5 )
A/C ratio= 6.0
A/C ratio= 4.5
A/C ratio= 3.0
10
15
20
25
30
35
40
45
10 15 20 25 30
Co
mp
ress
ive s
tren
gth
, f'
c (
MP
a)
Maximum size of CA (mm)
( W/C = 0.40 , CA/FA = 2.0 )
A/C ratio= 6.0
A/C ratio= 4.5
A/C ratio= 3.0
10
15
20
25
30
35
40
45
10 15 20 25 30
Co
mp
ress
ive
stre
ngth
, f'c
( M
Pa
)
Maximum size of CA (mm)
( W/C = 0.40 , CA/FA = 2.5 )
A/C ratio= 6.0
A/C ratio= 4.5
A/C ratio= 3.0
55
Fig. 4.7(b) Influence of maximum size of CA on compressive strength of concrete
with W/C =0.50
10
15
20
25
30
35
40
45
10 15 20 25 30
Co
mp
ress
ive s
tren
gth
, f'c
(
MP
a )
Maximum size of CA (mm)
( W/C = 0.50 , CA/FA = 1.5 )
A/C ratio= 6.0
A/C ratio= 4.5
A/C ratio= 3.0
10
15
20
25
30
35
40
45
10 15 20 25 30
Co
mp
ress
ive s
tren
gth
, f'c
( M
Pa
)
Maximum size of CA (mm)
( W/C = 0.50 , CA/FA = 2.0 )
A/C ratio= 6.0
A/C ratio= 4.5
A/C ratio= 3.0
10
15
20
25
30
35
40
45
10 15 20 25 30
Co
mp
ress
ive
stre
ngt
h,
f'c
( M
Pa
)
Maximum size of CA (mm)
( W/C = 0.50 , CA/FA = 2.5 )
A/C ratio= 6.0
A/C ratio= 4.5
A/C ratio= 3.0
56
Fig. 4.7(c) Influence of maximum size of CA on compressive strength of concrete with
W/C =0.60
10
15
20
25
30
35
40
45
10 15 20 25 30
Co
mp
ress
ive
stre
ngt
h,
f'c
( M
Pa
)
Maximum size of CA (mm)
( W/C = 0.60 , CA/FA = 1.5 )
A/C ratio = 6.0
A/C ratio = 4.5
A/C ratio = 3.0
10
15
20
25
30
35
40
45
10 15 20 25 30
Co
mp
ress
ive s
tren
gth
, f'c
(
MP
a )
Maximum size of CA (mm)
( W/C= 0.60 , CA/FA = 2.0 )
A/C ratio= 6.0
A/C ratio= 4.5
A/C ratio= 3.0
10
15
20
25
30
35
40
45
10 15 20 25 30
Co
mp
ress
ive s
tren
gth
, f'c
(
MP
a )
Maximum size of CA (mm)
( W/C = 0.60 , CA/FA = 2.5 )
A/C ratio = 6.0
A/C ratio = 4.5
A/C ratio= 3.0
57
The use of a larger maximum size of coarse aggregate affects strength in multiple ways.
Larger size aggregates have less surface area per unit volume, therefore, as the aggregate size
increases, water demand generally decreases. For this reason, a lower W/B ratio can be used,
and thus a higher strength is achieved. However, as the target strength of concrete increases,
the bond strength at the interfacial transition zone becomes increasingly important.
As the size of coarse aggregates decrease, the surface area per unit volume increases, thus
causing an increased water demand to produce concrete of equal consistency. Thus, in order
to maintain equal strength (i.e. equal W/B ratio), the binder content must be increased. With
respect to its influence on strength, the effect of transitioning from a larger to a smaller size
coarse aggregate depends on how the increase in water demand is addressed. Merely
increasing the water content in order to maintain equal consistency will cause strength to
decrease. However, changing from a larger to smaller aggregate while maintaining the W/B
ratio fixed will necessitate an increase in the cementitious materials content. With the
increased amount of paste aggregate bond provided for by the smaller aggregates, the net
result of maintaining a fixed W/B ratio would be an increase in measured strength.
The average values of the compressive strengths of concretes with maximum size of coarse
aggregate of 12.5, 19.0, and 25.0 are found to be 27.71, 28.10, and 26.99 MPa respectively
(Fig. 4.8). From this test data, it is found that the change in concrete strength is insignificant
with the variation in the maximum size of coarse aggregate.
Fig. 4.8 Variation in concrete strength with the variation in max size of CA
58
4.3.5 Influence of the partial replacement of cement by fly ash on concrete strength
Test results related to the influence of replacing (partial) cement with fly ash (FA) on the
strength of concrete are shown in Fig. 4.9. A control mix with cement (OPC) only (i.e. a fly
ash to cement, FA/C, ratio equals zero) along with two others with FA/C ratios of 10% and
20% (by weight) were considered in this study. For each of the three mixes, concrete
compressive strengths were determined at the age of 3, 7, 14, 28, 60, and 90 days. Test results
show (Fig. 4.9) that the strength of control mix is always higher than that of either the mixes
with FA/C ratio of 10% and 20%. This difference in strength is found to be higher at the early
ages and becomes smaller with the increase in concrete age.
Fig. 4.9 Influence of fly ash on compressive strength of concrete
The strength achievements of 10% fly ash content concretes with respect to the
corresponding strengths of reference concrete are found to be 77.63%, 83.31%, 86.15%,
90.47%, 92.52% and 96.88% at the concrete age of 3, 7, 14, 28, 60, and 90 days respectively.
Whereas, the corresponding strength achievements of 20% fly ash content concretes are
60.09%, 75.23%, 70.29%, 90.05%, 90.37% and 92.72% respectively. Concrete with 10%
replacement of cement shows higher strength than that of the corresponding concrete with
cement replacement of 20% for the whole range of concrete age considered. The 28-days
average strength of both the concretes containing fly ash (10% and 20%) is found to be 90%
of that of the concrete without any fly ash. And the difference between strengths of concretes
with cement replaced (partly) by fly ash or not becomes insignificant at 90 days.
0
5
10
15
20
25
30
35
40
45
0 14 28 42 56 70 84 98
Co
mp
ress
ive s
tren
gth
, f
' c (
MP
a )
Age of concrete ( Days )
( W/C = 0.50 , Max size =19 mm , CA/FA = 2 )
0 % fly ash
10 % fly ash
20 % fly ash
59
The pozzolanic reaction proceeds slowly, the initial strength of fly ash concrete tends to be
lower than that of concrete without fly ash. Due to continued pozzolnic reactivity concrete
develops greater strength at later age, which is almost equal to that of the concrete without fly
ash. Kaoser, (2006) also reported the same trend of change in concrete strength with the
replacement of cement with fly ash.
4.3.6 Comparison among the influence of various parameters on concrete strength
Based on the test results, a relative influence of test parameters on the increase in concrete
compressive strength are presented in Table 4.1. It is obvious that the water/cement (W/C)
ratio has the highest influence on the concrete strength. Next influential parameter is seen to
be the total aggregate/cement (A/C) ratio followed by that of the maximum size of coarse
aggregate. The coarse aggregate/fine aggregate (CA/FA) of 2.0 is seen to yield the highest
compressive strength. And a CA/FA ratio other than 2.0 results a reduction in concrete
strength.
Table 4.1: Relative influence of test variables on increasing concrete strength
Test variable Concrete strength, /
cf
(MPa)
% increase in /
cf
Water/cement (W/C)
ratio
0.60 22.37 ---
0.50 28.18 25.97%
0.40 32.23 44.08%
Aggregate/cement (A/C)
ratio
6.0 25.32 ---
4.5 27.77 9.68%
3.0 29.71 17.34%
Coarse aggregate/fine
aggregate (CA/FA) ratio
2.5 24.20 ---
2.0 31.18 28.84%
1.5 27.41 13.26%
Maximum size of coarse
aggregate (mm)
25.0 26.99 ---
19.0 28.10 4.11%
12.5 27.71 2.67%
60
CHAPTER 5
CONCLUSIONS AND RECOMMENDATIONS
5.1 General
In Bangladesh, unlike other countries of the world, broken brick aggregates, commonly
known as khoa is extensively used as cheaper and locally available substitute of natural
coarse aggregate for concrete. However, due to the lesser strength and stiffness of the brick
aggregate, concrete with brick aggregate may have some limitations in achieving its
compressive strength. This research aimed at in studying the influences of several main
parameters, such as (i) water/cement ratio, (ii) aggregate/cement ratio, (iii) coarse
aggregate/fine aggregate ratio, (iv) maximum size of coarse aggregate and (v) replacement of
cement by equal weight of fly ash, on the compressive strength of brick aggregate concretes.
The major findings of the research work are described in the following article.
5.2 Conclusions
1. The compressive strength of brick aggregate concrete is found to increase with the
decrease in W/C ratio (from 0.60 through 0.40). For the ranges of the parameters
considered in this study, the average values of the compressive strengths of concretes
with W/C ratio of 0.60, 0.50, and 0.40 are found to be 22.37, 28.18, and 32.23 MPa
respectively. This indicates an increase in compressive strengths of about 26.0% and
14.4% when the W/C ratio was decreased from 0.60 to 0.50 and 0.50 to 0.40 respectively.
2. Concrete compressive strength increases linearly with the decrease in total aggregate (fine
aggregate plus coarse aggregate)/cement ratio (A/C, by volume). An increase in
compressive strengths of about 9.7% and 7.0% are found when the A/C ratio was
decreased from 6.0 to 4.5 and 4.5 to 3.0 respectively. Eq. (4.1) represents the relation
between concrete strength and the aggregate/cement ratio.
3. The compressive strengths of brick aggregate concretes are found to be highest for the
coarse aggregate/fine aggregate (CA/FA) ratio (by volume) of 2.0. Whereas, either
increase or decrease in CA/FA ratio from 2.0 is found to yield a decrease in concrete
strength. The average values of the compressive strengths of concretes with CA/FA ratio
of 1.5, 2.0, and 2.5 are found to be 27.41, 31.18, and 24.20 MPa respectively.
61
4. Within the test parameters considered in this study, the maximum size of coarse aggregate
is found to have no significant influence on the concrete compressive strengths. The
average values of the compressive strengths of concretes with maximum size of coarse
aggregate of 12.5, 19.0, and 25.0 are found to be 27.71, 28.10, and 26.99 MPa
respectively.
5. At early ages the rate of strength development is lower for concrete containing fly ash
(partial) and the difference between the strengths of concretes with and without fly ash is
found to decrease with the increase of concrete age. The 28-days average strength of
concretes containing fly ash (10% and 20%) is found to be 90% of that of the concrete
without any fly ash. And the difference between the strengths of these concretes becomes
much smaller at 90 days.
6. The water/cement ratio has the highest influence on the compressive strength of brick
aggregate concrete. Next influential parameter is seen to be the total aggregate/cement
ratio followed by that of the maximum size of coarse aggregate. Whereas, the coarse
aggregate/fine aggregate (CA/FA) of 2.0 has been found to yield the highest strength of
concrete.
7. Higher strength concrete can be achieved by using good quality brick aggregates and
without using any admixture. In this study, a concrete with compressive strength of 37.97
MPa has been achieved considering water/cement ratio of 0.5, maximum size of coarse
aggregate of 12.5 mm and a mix ratio of 1:1:2 by volume.
5.3 Recommendations for future study
On the basis of the present study following recommendations are suggested for future study.
1. Achieving higher strength brick aggregate concrete considering water/cement ratio as low
as 0.25 (by weight) along with using appropriate admixture.
2. Tensile strength and stiffness of brick aggregate concrete can be studied considering the
same parameters as have been used in this study.
62
3. Effect of the grading of coarse aggregate on the properties of brick aggregate concrete.
4. Effect of fly ash on the properties of brick aggregate concrete considering partial
replacement of cement with fly ash at an increment of 5% and up to 50%.
63
REFERENCES
Abebe Dinku, “The Need for Standardization of Aggregates for Concrete Production in Ethiopian Construction Industry”, Aggregate Conference Abebe, 15 pp (May, 2005).
ACI Committee 211 (ACI 211.4R-93) (1993), “Guide for Selecting Proportions for High-Strength Concrete with Portland Cement and Fly Ash,” American Concrete Institute, Detroit, Michigan, 13 pp. ACI Committee 232 (ACI 232.2R-96) (2002), “Guide for Selecting Proportions for High-Strength Concrete with Portland Cement and Fly Ash,” American Concrete Institute, Detroit, Michigan, 232.2R, 716 pp. ACI Committee 318, (1989), “Building Code Requirements for Reinforced Concrete Construction AND company (ACI 318-89/ACI 318R-89),” American Concrete Institute Detroit, 347 pp. ACI 309.1R-93, Behavior of fresh concrete durinf vibration, ACI Manual of Concrete Practice, part 2: Construction practices and Inspection Pavements, 19 pp. (Detroit, Michigan, 1994). ACI SP-79, (1983), “Fly ash, silica fume, Slag and Other Mineral by products in concrete” V.2, V. M. Malhotra, Editor. Akhtaruzzaman A. A. and Hasnat A. (1983), “Properties of concrete using crushed brick as aggregate”, Concrete International, Vol. 5, No. 2, pp.58-63. ASTM C39-96, “Standard Test Method for Compressive strength of Cylindrical Concrete Specimens”. ASTM C109-99, “Standard Test Method for Compressive Strength of Hydraulic Cement Mortars”. ASTM C150-98, “Standard Specification for Portland Cement”. ASTM C187, “Test Method for Normal Consistency of Hydraulic Cement”. ASTM C191-99, “Standard Test Method for Time of Setting of Hydraulic Cement by Vicat Needle”. ASTM C125-93, “Standard Test Method for Terminology Relating to Concrete and Concrete Aggregates”. ASTM C 618 Specifications for Fly Ash and Raw or Calcined Natural Pozzolan for Use as a Mineral Admixture in Portland cement Concrete.
64
Bazaz J. B., Khayati M., Akrami N., “Performance of concrete Produced with Crushed Bricks as the Coarse and Fine Aggregate” IAEG 2006, 616 pp. Bureau of Indian Standards, New Delhi, SP 23:1982: Handbook on concrete mixes Second reprint December 1990, 144 pp. Caldarone, M. A., (2009), “High-Strength Concrete”, Library of Congress Cataloging-in-Publication Data, 1st edition, 252 pp. Chandaprasirt, P., Jaturapitakkul, C., and Sinsiri, T., (2005) “Effect of fly ash fineness on compressive strength and pore size of blended cement past” Cement and concrete composites, 27, pp.425-428. Cordon, W. A., “Variables in concrete aggregates and Portland cement past which influence the strength of concrete” Journal of the American Concrete Institute, Vol, 60, No.8, August 1963, pp.1029-1051. Cordon, W. A., and Thorpe, J. D., (1975), “Proportioning and Evaluation of Concrete Mixtures,” ACI Journal, Proceeding V.72, No.2, pp.46-49. Duggal, S. K., (2008), “Building Materials”, New Age International (P) Ltd, Publishers, India, 3rd edition, 525 pp. Gambhir M. H. (1993), “Concrete Technology”, Tata McGraw-Hill Publishing Co. Ltd, India, 4th reprint, 318 pp. http://www.engr.psu.edu/ce/.../concrete/.../Aggregate/Aggregatesmain.htm (Accessed on June 14,2011) http://www.saifulamin.info/publication/conference_proceeding/c12.pdf http:// (Accessed on June 14, 2011) Kaoser A. R., (2006), “Study on Strength and Durability of Brick Aggregate Concrete with Fly Ash,” M. Sc thesis, Bangladesh University of Engineering and Technology, Dhaka, Bangladesh. Khaloo A. R. (1994), “Properties of concrete using crushed clinker brick as coarse aggregate”, ACI Materials Journal, Vol. 91, No. 2, pp.401-407. Kazberuk, M. K., and Lelusz, M., (2007), “Strength Development of Concrete with Fly Ash addition”, Journal of Civil Engineering and Management, Vol XIII, No 2, pp.115–122. Manmohan, d., and Metha, p. k., (1981), “Influence of Pozzolanic, Slage and Chemical Admixtures on Pore Size Distribution and Permeability of Hardened Cement Pastes”, Cement, concrete and aggregates, V.3, No.1, pp.63-67.
65
Mansur M. A, Wee T. H. and Cheran L. S. (1999), “Crushed bricks as coarse aggregate for concrete”, ACI Materials Journal, Vol. 96, No. 4, pp.478-484. Mehta, P. K., (2001), “Concrete Microstructure, Properties and Materials”, 1st edition, 239 pp. Mindess, S., Young, J.F., and Darwin, D. (2003), Concrete, Second Edition, Prentice-Hall, Upper Saddle River, NJ, 644 pp. Neville A. M. (1995), “Properties of Concrete”, Longman, Malaysia, 4th edition, 844 pp. Rashid M. A., Hossain T., and Islam M. A., (2009), “Properties of higher strength Concrete made with crushed brick as course aggregate”, Journal of Civil Engineering, IEB, Vol. CE-37, No.1, pp.43-52. Rashid M. A. and Mansur M. A. (2009), “Considerations in producing high strength Concrete”, Journal of Civil Engineering, IEB, Vol. CE-37, No.1, pp.53-63. Regourd, M., 1983, “Technology in the 1990's Development in Hydraulic Cements,”Proceedings A310.5, Philosophical Transactions, Royal Society of London, pp.85-91. Roy, D. M.; Skalny, J.; and Diamond, Sidney, 1982, "Effects of Blending Materials on the Rheology of Cement Pasts and Concretes," Proceedings, Symposium M, Concrete Rheology, Materials Research Society, Pittsburgh, pp.152-173. Shetty M. S. (1988), “Concrete Technology”, S. Chand & Company Ltd., India, 3rd edition, 608 pp. Verbeck, George, 1960, “Chemistry of the Hydration of Portland Cement,” Proceedings, 4th International Symposium on the Chemistry of Cement (Washington, D.C., Oct.), Monograph No. 43, U.S. National Bureau of Standards,Washington, D.C., pp.453-465. Wei, F.; Grutzeck, M. W.; and Roy, D. M., 1984, “Effects of Fly Ash on Hydration of Cement Pastes,” Ceramic Bulletin, V. 63, 471 pp.
66
APPENDIX A
PROPERTIES OF MATERIALS USED
A.1. Properties of cement
Table A.1.1: Normal consistency test of cement
Batch no
Weight
of sample
(gm)
% of
water
Volume
unit of
water
(ml)
Penetration of
φ10 mm
plunger in 30
second
Remarks
01
500
30%
150
10
11-30 am
Table A.1.2: Initial setting time and final setting time test of cement (Starting time: 11-30 am)
Reading
no Reading time
Penetration
(mm) Remarks
1 11-45 am 40
2 12-00 pm 40
3 12.15 pm 39
4 12-30 pm 38.5
5 12-45 pm 38
6 01-00 pm 38
7 01-15 pm 37.5
8 01-30 pm 37
9 01-45 pm 37
10 02-00 pm 37
11 02-15 pm 37
12 02-30 pm 37
13 02-45 pm 35
14 03-00 pm 34
15 03-15 pm 33.5 Initial setting time
(3-17) 16 03-30 pm 20
17 03-45 pm 14
18 04-00 pm 3
19 04-15 pm 1
20 04-30 pm spotted
21 04-45 pm spotted
22 05-00 pm spotted
23 05-15 pm spotted
24 05-30 pm Not spotted Final setting time (5-45)
67
Table A.1.3: Compressive strength test on cement cube
Sl.
no
Curing
Age
(Days)
Size(mm)
Cross-
sectional
Area (mm2)
Crushing
Load
(KN)
Crushing
Strength
(MPa)
Average
Crushing
Strength
( MPa)
01
07
L=
3
05.5104.5103.51 ++
=51.04
2612.74
72
27.55
28.06
B=
3
17.5121.5120.51 ++
=51.19
02
07
L=
3
37.5142.5152.51 ++
=51.45
2660.48
73
27.44
B=
3
75.5171.5168.51 ++
=51.71
03
07
L=
3
11.5109.5100.51 ++
=51.07
2658.70
77.6
29.19
B=
3
02.5205.5211.52 ++
=52.06
04
28
L=
3
04.5105.5102.51 ++
=51.04
2613.59
93.6
35.81
36.52
B=
3
18.5123.5121.51 ++
=51.19
05
28
L=
3
38.5140.5153.51 ++
=51.45
2654.44
92
34.66 B=
3
76.5172.5169.51 ++
=51.71
06
28
L=
3
12.5110.5101.51 ++
=51.07
2659.58
104
39.11 B=
3
03.5206.5212.52 ++
=52.06
68
A.2. Properties of fine aggregate
For fine aggregate fineness modulus, absorption capacity and are determined according to
respective codes.
Table A.2.1: Gradation Chart of fine aggregate (1-81 sets) (ASTM C117-84a & ASTM
C136-84a) (Sample weight =500 gm)
Sieve size
(mm)
Weight of
retained
(gm)
% of
retained
(gm)
Cumulative
% of
retained
% of finer
4 0 0 0 100
8 4.2 0.84 0.84 99.16
16 53 10.6 11.44 88.56
30 198.4 39.84 51.28 48.72
50 170.6 34.25 85.53 14.47
100 69.2 13.89 99.42 0.58
Sum ---- ---- 248.51 ----
FM= 100
51.248 =2.485
Fig. A.2.1: Grain size distribution of fine aggregate for first phases.
0
20
40
60
80
100
120
0.1 1 10
% o
f f
iner
Sieve size(mm)
Grain size distribution of sylhet sand
69
Table A.2.2: Gradation Chart of fine aggregate (82-84 sets) (ASTM C117-84a & ASTM
C136-84a) (Sample weight =500 gm)
Sieve size
(mm)
Weight of
retained
(gm)
% of
retained
(gm)
Cumulative
% of
retained
% of finer
4 0 0 0 100
8 21.4 4.28 4.28 95.72
16 101.9 20.38 24.66 75.34
30 253.1 50.62 75.28 24.72
50 101.1 20.22 95.50 4.5
100 17 3.4 98.90 1.1
Sum ---- ---- 298.62 ----
FM= 100
62.298 =2.98
Fig. A.2.2: Grain size distribution of fine aggregate for second phases.
0
20
40
60
80
100
120
0.1 1 10
% o
f fin
er
Sieve size (mm)
Grain size distribution of sylhet sand
70
A.2.1 Absorption Capacity of fine aggregate
Jar weight =.13 kg
Jar weight +oven dry sample weight =.63kg
Oven dry sample weight, A = .5 kg
Saturated surface dry sample weight in air, B =0.50985
Percentage of absorption = A
AB −X 100 =
5.0
5.050985.0 −
X 100 =1.97 %
Jar weight =0.13 kg
Jar weight +oven dry sample weight =0.63kg
Oven dry sample weight, A =12.5 kg
Saturated surface dry sample weight in air, B =12.54
Percentage of absorption = A
AB −X 100 =
5.0
5.051.0 −X 100 =2.0 % (considered)
A.3. Properties of coarse aggregate
Table A.3.1: Gradation Chart of 25.0 mm down graded coarse aggregate (ASTM C117-84a &
ASTM C136-84a) (Sample weight =5000 gm)
Sieve size
(mm)
Weight of
retained
(gm)
% of
retained
(gm)
Cumulative
% of
retained
% of finer
37.5 0 0 0 100
19 1000 20 20 80
9.5 3393 67.86 87.86 12.14
4.75 580 11.6 99.46 0.54
2.36 25 0.5 99.96 0.54
1.18 2 0.04 100 0.04
0.6 0 0 100 0
0 .3 0 0 100 0
0.15 0 0 100 0
Sum 5000 100 707.28
FM= 100
28.707 =7.073
71
Fig. A.3.1: Grain size distribution of coarse aggregate for 25 mm down graded.
Table A.3.2: Gradation Chart of 19.0 mm down graded coarse aggregate (ASTM C117-84a &
ASTM C136-84a) (Sample weight =5000 gm)
Sieve size
(mm)
Weight of
retained
(gm)
% of
retained
(gm)
Cumulative
% of
retained
% of finer
37.5 0 0 0 100
19 0 0 0 100
9.5 3980 79.6 79.6 20.4
4.75 950 19 98.6 1.4
2.36 70 1.4 100 0
1.18 0 0 100 0
0.6 0 0 100 0
0.3 0 0 100 0
0.15 0 0 100 0
Sum 5000 100 678.2
FM= 100
2.678 =6.782
0
20
40
60
80
100
120
0.1 1 10 100
% of
finer
Sieve size (mm)
25 mm grain size distribution curve
72
Fig. A.3.2: Grain size distribution of coarse aggregate for 19 mm down graded.
Table A.3.3: Gradation Chart of 12.5 mm down graded coarse aggregate (ASTM C117-84a &
ASTM C136-84a) (Sample weight =5000 gm)
Sieve size
(mm)
Weight of
retained
(gm)
% of
retained
(gm)
Cumulative
% of
retained
% of finer
37.5 0 0 0 100
19 0 0 0 100
9.5 1770 35.4 35.4 64.6
4.75 2750 55 90.4 9.6
2.36 480 9.6 100 0
1.18 0 0 100 0
0.6 0 0 100 0
0.3 0 0 100 0
0.15 0 0 100 0
Sum 5000 100 625.8
FM= 100
8.625 =6.258
0
20
40
60
80
100
120
0.1 1 10 100
% of
fin
er
Sieve size (mm)
19.0 mm grain size distribution curve
73
Fig. A.3.3: Grain size distribution of coarse aggregate for 12.5 mm down graded.
A.3.1. Absorption Capacity of coarse aggregate
Jar weight =1.61 kg
Jar weight +oven dry sample weight =6.61kg
Oven dry sample weight, A =5 kg
Saturated surface dry sample weight in air, B =5.57
Percentage of absorption = A
AB −X 100 =
00.5
00.557.5 −
X 100 =11.4 %
0
20
40
60
80
100
120
0.1 1 10 100
% of f
iner
Sieve size (mm)
12.5 mm grain size distribution curve
74
APPENDIX B
TEST DATA
Table B.1: Casting ratio and weight of ingredients of sample specimens
Sl
no
Max.
size
of
CA
(mm)
Mixing ratio
(by volume)
W/C
ratio
(by
weight)
Fly ash
(by
weight)
Cement
(Kg)
Sand
(Kg)
Khoa
(Kg)
Water
(Kg)
Fly
ash
(Kg)
1 25.0 1 : 2 : 4 0.60 ------- 6.97 14.45 18 4.18+2.11 ----
2 19.0 1 : 2 : 4 0.60 ------- 6.66 13.80 18 4.0+1.86 ----
3 12.5 1 : 2 : 4 0.60 ------- 6.49 13.45 18 3.89+1.71 ----
4 25.0 1 : 1.5 : 3 0.60 ------ 9.29 14.45 18 5.57+2.11 -----
5 19.0 1 : 1.5 : 3 0.60 ------- 8.88 13.80 18 5.33+1.86 -----
6 12.5 1 : 1.5 : 3 0.60 ------- 8.66 13.45 18 5.19+1.71 ----
7 25.0 1 : 1 : 2 0.60 ------- 13.94 14.44 18 8.36+1.79 -----
8 19.0 1 : 1 : 2 0.60 ------- 13.32 13.80 18 7.99+1.91 -----
9 12.5 1 : 1 : 2 0.60 ------- 12.98 13.45 18 7.79+1.83 ----
10 25.0 1 : 2 : 4 0.50 -------- 6.97 14.44 18 3.49+1.79 ----
11 19.0 1 : 2 : 4 0.50 -------- 6.66 13.80 18 3.33+1.91 ----
12 12.5 1 : 2 : 4 0.50 -------- 6.49 13.45 18 3.25+1.83 ----
13 25.0 1 : 1.5 : 3 0.50 -------- 9.29 14.44 18 4.65+1.66 -----
14 19.0 1 : 1.5 : 3 0.50 -------- 8.88 13.80 18 4.44+1.86 -----
15 12.5 1 : 1.5 : 3 0.50 -------- 8.66 13.45 18 4.33+1.94 -----
16 25.0 1 : 1 : 2 0.50 -------- 13.94 14.44 18 6.97+1.66 -----
17 19.0 1 : 1 : 2 0.50 -------- 13.32 13.80 18 6.66+1.86 -----
18 12.5 1 : 1 : 2 0.50 -------- 12.98 13.48 18 6.49+1.94 ----
19 25.0 1 : 2 : 4 0.40 -------- 6.74 13.97 17.4 2.70+1.86 -----
20 19.0 1 : 2 : 4 0.40 -------- 6.44 13.34 17.4 2.58+1.74 -----
21 12.5 1 : 2 : 4 0.40 --------- 6.28 13.00 17.4 2.51+2.12 -----
75
Sl
no
Max.
size
of
CA
(mm)
Mixing ratio
(by volume)
W/C
ratio
(by
weight)
Fly ash
(by
weight)
Cement
(Kg)
Sand
(Kg)
Khoa
(Kg)
Water
(Kg)
Fly
ash
(Kg)
22 25.0 1 : 1.5 : 3 0.40 -------- 8.98 13.97 17.4 3.60+1.86 -----
23 19.0 1 : 1.5 : 3 0.40 -------- 8.58 13.94 17.4 3.43+1.74 -----
24 12.5 1 : 1.5 : 3 0.40 -------- 8.37 13.00 17.4 3.35+2.12 -----
25 25.0 1 : 1 : 2 0.40 -------- 13.48 13.97 17.4 5.39+1.87 -----
26 19.0 1 : 1 : 2 0.40 -------- 12.88 13.34 17.4 5.15+2.12 -----
27 12.5 1 : 1 : 2 0.40 --------- 12.55 13.00 17.4 5.02+2.09 -----
28 25.0 1 : 2.4 : 3.6 0.60 -------- 7.49 18.62 17.4 4.49+1.96 -----
29 19.0 1 : 2.4 : 3.6 0.60 -------- 7.15 17.79 17.4 4.29+2.21 ----
30 12.5 1 : 2.4 : 3.6 0.60 --------- 6.97 17.34 17.4 4.18+2.18 -----
31 25.0 1 : 1.8 : 2.7 0.60 -------- 9.98 18.62 17.4 5.99+1.96 -----
32 19.0 1 : 1.8 : 2.7 0.60 -------- 9.54 17.79 17.4 5.72+2.21 -----
33 12.5 1 : 1.8 : 2.7 0.60 --------- 9.30 17.34 17.4 5.58+2.18 -----
34 25.0 1 : 1.2 : 1.8 0.60 -------- 14.97 18.62 17.4 8.97+1.79 ----
35 19.0 1 : 1.2 : 1.8 0.60 -------- 14.31 17.79 17.4 8.59+2.09 ----
36 12.5 1 : 1.2 : 1.8 0.60 --------- 13.94 17.34 17.4 8.36+2.10 ----
37 25.0 1 : 2.4 : 3.6 0.50 -------- 7.49 18.62 17.4 3.75+1.79 -----
38 19.0 1 : 2.4 : 3.6 0.50 -------- 7.15 17.79 17.4 3.58+2.09 -----
39 12.5 1 : 2.4 : 3.6 0.50 --------- 6.97 17.34 17.4 3.49+2.10 -----
40 25.0 1 : 1.8 : 2.7 0.50 -------- 9.98 18.62 17.4 4.99+1.79 ----
41 19.0 1 : 1.8 : 2.7 0.50 -------- 9.54 17.79 17.4 4.77+2.09 ----
42 12.5 1 : 1.8 : 2.7 0.50 --------- 9.30 17.34 17.4 4.65+2.10 -----
43 25.0 1 : 1.2 : 1.8 0.50 -------- 14.84 18.46 17.25 7.42+2.11 -----
44 19.0 1 : 1.2 : 1.8 0.50 -------- 14.18 17.64 17.25 7.09+2.00 -----
45 12.5 1 : 1.2 : 1.8 0.50 --------- 13.82 17.19 17.25 6.91+2.17 -----
76
Sl
no
Max.
size
of
CA
(mm)
Mixing ratio
(by volume)
W/C
ratio
(by
weight)
Fly ash
(by
weight)
Cement
(Kg)
Sand
(Kg)
Khoa
(Kg)
Water
(Kg)
Fly
ash
(Kg)
46 25.0 1 : 2.4 : 3.6 0.40 -------- 7.42 18.46 17.25 2.97+2.11 -----
47 19.0 1 : 2.4 : 3.6 0.40 -------- 7.09 17.64 17.25 2.84+2.00 -----
48 12.5 1 : 2.4 : 3.6 0.40 --------- 6.91 17.19 17.25 2.76+2.17 -----
49 25.0 1 : 1.8 : 2.7 0.40 -------- 9.72 18.14 16.95 3.89+1.96 -----
50 19.0 1 : 1.8 : 2.7 0.40 -------- 9.13 17.1 16.65 3.65+2.12 -----
51 12.5 1 : 1.8 : 2.7 0.40 --------- 8.66 16.15 16.2 3.46+1.48 -----
52 25.0 1 : 1.2 : 1.8 0.40 -------- 13.68 17.01 15.9 5.47+1.84 -----
53 19.0 1 : 1.2 : 1.8 0.40 -------- 13.10 16.26 15.9 5.24+2.03 -----
54 12.5 1 : 1.2 : 1.8 0.40 --------- 12.74 15.85 15.9 5.1+1.46 -----
55 25.0 1 : 1.714 : 4.286 0.60 -------- 6.29 11.17 17.4 3.77+1.42 -----
56 19.0 1 : 1.714 : 4.286 0.60 -------- 6.23 10.68 17.4 3.74+1.94 -----
57 12.5 1 : 1.714 : 4.286 0.60 --------- 5.86 10.41 17.4 3.52+2.04 -----
58 25.0 1 : 1.286 : 3.214 0.60 -------- 8.39 11.17 17.4 5.03+1.43 -----
59 19.0 1 : 1.286 : 3.214 0.60 -------- 8.10 10.68 17.4 4.86+1.94 -----
60 12.5 1 : 1.286 : 3.214 0.60 --------- 7.81 10.41 17.4 4.69+2.04 -----
61 25.0 1 : .857 : 2.143 0.60 -------- 12.58 11.17 17.4 7.55+1.43 -----
62 19.0 1 : .857 : 2.143 0.60 -------- 12.1 10.68 17.4 7.26+1.94 -----
63 12.5 1 : .857 : 2.143 0.60 --------- 11.71 10.41 17.4 7.10+2.04 -----
64 25.0 1 : 1.714 : 4.286 0.50 -------- 6.29 11.17 17.4 3.15+1.69 -----
65 19.0 1 : 1.714 : 4.286 0.50 -------- 6.17 10.95 17.85 3.10+1.92 -----
66 12.5 1 : 1.714 : 4.286 0.50 --------- 6.10 10.67 17.85 3.10+1.21 -----
67 25.0 1 : 1.286 : 3.214 0.50 -------- 8.60 11.46 17.85 4.30+1.74 -----
68 19.0 1 : 1.286 : 3.214 0.50 -------- 8.22 10.95 17.85 4.11+1.93 -----
69 12.5 1 : 1.286 : 3.214 0.50 --------- 8.01 10.67 17.85 4.0+1.22 ----
77
Sl
no
Max.
size
of
CA
(mm)
Mixing ratio
(by volume)
W/C
ratio
(by
weight)
Fly ash
(by
weight)
Cement
(Kg)
Sand
(Kg)
Khoa
(Kg)
Water
(Kg)
Fly
ash
(Kg)
70 25.0 1 : .857 : 2.143 0.50 -------- 12.90 11.46 17.85 6.45+1.62 -----
71 19.0 1 : .857 : 2.143 0.50 -------- 12.33 10.95 17.85 6.17+2.07 -----
72 12.5 1 : .857 : 2.143 0.50 -------- 12.01 10.67 17.85 6.01+1.66 -----
73 25.0 1 : 1.714 : 4.286 0.40 -------- 6.45 11.46 17.85 2.58+1.62 -----
74 19.0 1 : 1.714 : 4.286 0.40 -------- 6.16 10.95 17.85 2.46+2.07 -----
75 12.5 1 : 1.714 : 4.286 0.40 --------- 6.01 10.67 17.85 2.41+1.66 -----
76 25.0 1 : 1.286 : 3.214 0.40 -------- 8.60 11.46 17.85 3.44+1.62 -----
77 19.0 1 : 1.286 : 3.214 0.40 -------- 8.22 10.95 17.85 3.29+2.07 -----
78 12.5 1 : 1.286 : 3.214 0.40 -------- 8.01 10.67 17.85 3.20+1.66 -----
79 25.0 1 : .857 : 2.143 0.40 -------- 12.90 11.46 17.85 5.16+ 2 -----
80 19.0 1 : .857 : 2.143 0.40 -------- 12.33 10.95 17.85 4.93+2.13 -----
81 12.5 1 : .857 : 2.143 0.40 --------- 12.01 10.67 17.85 4.80+1.90 -----
82 19.0 1 : 1.5 : 3 0.50 10% 7.72 13.34 17.4 4.29+2 0.86
83 19.0 1 : 1.5 : 3 0.50 20% 7.10 13.80 18 4.44+2 1.78
84 19.0 1 : 1.5 : 3 0.50 --------- 8.88 13.80 18 4.44+2.09 -----
78
Table B.2: Compressive strength of concrete
Sl. no Dia.1
(mm)
Dia.2
(mm)
Dia.3
(mm)
Sum
dia.
(mm)
Avg.
dia.
(mm)
Radius
(mm)
Area
(mm2)
Load
(KN)
Str.
(Mpa)
Avg.
str.
(Mpa)
1A 149.6 149.7 149.9 449.2 149.73 74.87 17599.76 578 32.84
1B 151.5 149.9 149.9 450.3 150.1 75.05 17686.06 647 36.58 33.88
1C 150.9 1512.5 1512.5 451.9 150.63 75.32 17811.96 574 32.23
2A 149.4 149.7 149.9 449 149.67 74.83 17584.09 454 25.82
2B 153.1 153.4 153.4 459.9 153.3 76.65 18448.2 449 24.34 24.57
2C 150.1 150.6 150.9 451.6 1512.53 75.27 17788.32 419 23.55
3A 151.2 151.4 151.7 454.3 151.43 75.72 18001.66 534 29.66
3B 152 152.4 152.5 456.9 152.3 76.15 18208.3 453 24.88 28.48
3C 150.2 150.1 149.9 450.2 150.07 75.03 17678.2 546 30.89
4A 153.1 153.4 153.5 460 153.33 76.67 18456.22 322 17.45
4B 150 150.4 150.4 450.8 150.27 75.13 17725.36 337 19.01 17.89
4C 151.2 151.5 151.9 454.6 151.53 75.77 18025.45 310 17.2
5A 152.1 152.4 152.5 457 152.33 76.17 18216.27 549 30.14
5B 152.2 152.4 152.5 457.1 152.37 76.18 18224.25 545 29.91 29.97
5C 150.1 150.4 1512.5 451 150.33 75.17 17741.09 530 29.87
6A 149.2 149.5 149.7 448.4 149.47 74.73 17537.12 508 28.97
6B 149.2 149.6 149.9 448.7 149.57 74.78 17560.6 529 30.12 29.31
6C 151.1 151.2 151.4 453.7 151.23 75.62 17954.14 518 28.85
7A 149.5 149.6 149.9 449 149.67 74.83 17584.09 442 25.14
7B 150.2 150.4 1512.5 451.1 150.37 75.18 17748.96 490 27.61 25.66
7C 151.1 151.2 151.4 453.7 151.23 75.62 17954.14 435 24.23
8A 150.8 151.2 151.4 453.4 151.13 75.57 17930.41 474 26.44
8B 148.5 148.9 150.1 447.5 149.17 74.58 17466.8 448 25.65 26.7
8C 149.2 149.5 149.6 448.3 149.43 74.72 17529.3 491 28.01
79
Sl. no Dia.1
(mm)
Dia.2
(mm)
Dia.3
(mm)
Sum
dia.
(mm)
Avg.
dia.
(mm)
Radius
(mm)
Area
(mm2)
Load
(KN)
Str.
(Mpa)
Avg.
str.
(Mpa)
9A 152.3 152.5 152.5 457.3 152.43 76.22 18240.2 542 29.71
9B 153.1 153.4 153.6 460.1 153.37 76.68 18464.25 530 28.7 28.96
9C 153.2 153.4 153.6 460.2 153.4 76.7 18472.27 526 28.48
10A 152 152.2 152.3 456.5 152.17 76.08 18176.44 520 28.61
10B 152.4 152.5 152.7 457.6 152.53 76.27 18264.14 516 28.25 29.52
10C 152.9 152.9 153 458.8 152.93 76.47 18360.05 582 31.7
11A 150.1 150.3 150.4 450.8 150.27 75.13 17725.36 471 26.57
11B 151.3 151.5 151.9 454.7 151.57 75.78 18033.38 540 29.94 28.57
11C 151.2 151.4 151.5 454.1 151.37 75.68 17985.82 525 29.19
12A 149.9 150.2 1512.5 450.6 150.2 75.1 17709.63 519 29.31
12B 151.2 151.3 151.5 454 151.33 75.67 17977.9 510 28.37 28.49
12C 151.3 151.4 151.5 454.2 151.4 75.7 17993.74 500 27.79
13A 1512.5 150.9 151.2 452.6 150.87 75.43 17867.19 552 30.89
13B 149.9 1512.5 150.6 451 150.33 75.17 17741.09 546 30.78 30.3
13C 151.1 150.7 150.7 452.5 150.83 75.42 17859.3 522 29.23
14A 149.9 150.1 150.2 450.2 150.07 75.03 17678.2 570 32.24
14B 149.7 149.9 150.1 449.7 149.9 74.95 17638.96 602 34.13 32.69
14C 151.2 151.3 151.5 454 151.33 75.67 17977.9 570 31.71
15A 152.2 152.4 152.5 457.1 152.37 76.18 18224.25 608 33.36
15B 150.2 1512.5 150.9 451.6 1512.53 75.27 17788.32 591 33.22 32.66
15C 153.2 153.5 153.6 460.3 153.43 76.72 18480.3 580 31.38
16A 153.2 153.5 153.9 460.6 153.53 76.77 18504.4 619 33.45
16B 153.1 153.5 153.6 460.2 153.4 76.7 18472.27 593 32.1 33.66
16C 152.2 152.4 152.9 457.5 152.5 76.25 18256.16 647 35.44
80
Sl. no Dia.1
(mm)
Dia.2
(mm)
Dia.3
(mm)
Sum
dia.
(mm)
Avg.
dia.
(mm)
Radius
(mm)
Area
(mm2)
Load
(KN)
Str.
(Mpa)
Avg.
str.
(Mpa)
17A 150.9 151.2 151.3 453.4 151.13 75.57 17930.41 608 33.91
17B 151.2 151.3 151.5 454 151.33 75.67 17977.9 680 37.82 36.56
17C 153.1 153.2 153.5 459.8 153.27 76.63 18440.18 700 37.96
18A 152.2 152.4 152.5 457.1 152.37 76.18 18224.25 674 36.98
18B 151.5 151.9 152.1 455.5 151.83 75.92 18096.89 710 39.23 37.97
18C 151.5 151.9 152.1 455.5 151.83 75.92 18096.89 682 37.69
19A 148.9 149.1 149.3 447.3 149.1 74.55 17451.19 510 29.22
19B 149.8 149.9 150.2 449.9 149.97 74.98 17654.65 501 28.38 28.43
19C 149.4 149.6 149.7 448.7 149.57 74.78 17560.6 486 27.68
20A 152.1 152.3 152.8 457.2 152.4 76.2 18232.22 658 36.09
20B 149.7 149.9 150.1 449.7 149.9 74.95 17638.96 640 36.28 36.64
20C 147.9 148.2 148.4 444.5 148.17 74.08 17233.39 647 37.54
21A 153.1 153.4 153.6 460.1 153.37 76.68 18464.25 560 30.33
21B 152.2 152.4 152.5 457.1 152.37 76.18 18224.25 562 30.84 29.83
21C 151.9 152.3 152.5 456.7 152.23 76.12 18192.37 515 28.31
22A 152.5 152.8 152.9 458.2 152.73 76.37 18312.06 636 34.73
22B 151.1 151.3 151.4 453.8 151.27 75.63 17962.06 601 33.46 33.74
22C 152.3 152.3 152.5 457.1 152.37 76.18 18224.25 602 33.03
23A 153.2 153.3 153.3 459.8 153.27 76.63 18440.18 651 35.3
23B 150.4 1512.5 150.7 451.6 1512.53 75.27 17788.32 650 36.54 36.62
23C 150.1 149.9 149.9 449.9 149.97 74.98 17654.65 671 38.01
24A 152.1 152.3 152.5 456.9 152.3 76.15 18208.3 640 35.15
24B 152.2 152.3 152.4 456.9 152.3 76.15 18208.3 648 35.59 35.31
24C 151.1 151.3 151.4 453.8 151.27 75.63 17962.06 632 35.19
81
Sl. no Dia.1
(mm)
Dia.2
(mm)
Dia.3
(mm)
Sum
dia.
(mm)
Avg.
dia.
(mm)
Radius
(mm)
Area
(mm2)
Load
(KN)
Str.
(Mpa)
Avg.
str.
(Mpa)
25A 149.4 149.6 149.7 448.7 149.57 74.78 17560.6 642 36.56
25B 148.9 149.5 149.6 448 149.33 74.67 17505.85 580 33.13 34.68
25C 150.9 150.4 149.9 451.2 150.4 75.2 17756.83 610 34.35
26A 150.1 150.2 150.9 451.2 150.4 75.2 17756.83 620 34.92
26B 149.9 150.4 150.7 451 150.33 75.17 17741.09 623 35.12 35.29
26C 149.5 149.6 149.9 449 149.67 74.83 17584.09 630 35.83
27A 152.4 151.8 151.9 456.1 152.03 76.02 18144.6 652 35.93
27B 151.9 151.9 152.2 456 152 76 18136.64 648 35.73 35.57
27C 150.9 151.4 151.6 453.9 151.3 75.65 17969.98 630 35.06
28A 153.1 153.4 153.2 459.7 153.23 76.62 18432.16 370 20.07
28B 153.3 153.4 153.5 460.2 153.4 76.7 18472.27 351 19 19.57
28C 152.8 152.9 152.9 458.6 152.87 76.43 18344.05 360 19.62
29A 147.9 148.4 148.6 444.9 148.3 74.15 17264.42 377 21.84
29B 150.2 150.4 150.6 451.2 150.4 75.2 17756.83 391 22.02 21.86
29C 151.1 151.2 151.3 453.6 151.2 75.6 17946.23 390 21.73
30A 150.2 150.4 150.6 451.2 150.4 75.2 17756.83 383 21.57
30B 150.2 150.4 150.6 451.2 150.4 75.2 17756.83 383 21.57 21.6
30C 151.2 151.4 151.6 454.2 151.4 75.7 17993.74 390 21.67
31A 153.2 153.4 153.5 460.1 153.37 76.68 18464.25 418 22.64
31B 153.1 153.2 153.3 459.6 153.2 76.6 18424.14 432 23.45 23.39
31C 152.1 152.4 152.6 457.1 152.37 76.18 18224.25 439 24.09
32A 149.1 149.3 149.4 447.8 149.27 74.63 17490.22 391 22.36
32B 149.4 149.5 149.6 448.5 149.5 74.75 17544.95 369 21.03 21.16
32C 149.3 149.4 149.5 448.2 149.4 74.7 17521.48 352 20.09
82
Sl. no Dia.1
(mm)
Dia.2
(mm)
Dia.3
(mm)
Sum
dia.
(mm)
Avg.
dia.
(mm)
Radius
(mm)
Area
(mm2)
Load
(KN)
Str.
(Mpa)
Avg.
str.
(Mpa)
33A 150.1 150.3 1512.5 450.9 150.3 75.15 17733.22 412 23.23
33B 149.9 150.1 150.4 450.4 150.13 75.07 17693.91 424 23.96 23.11
33C 150.2 150.4 150.6 451.2 150.4 75.2 17756.83 393 22.13
34A 153.5 153.6 153.9 461 153.67 76.83 18536.55 425 22.93
34B 152.2 152.3 152.4 456.9 152.3 76.15 18208.3 380 20.87 22.09
34C 151.2 151.3 151.4 453.9 151.3 75.65 17969.98 404 22.48
35A 153.4 153.5 153.7 460.6 153.53 76.77 18504.4 383 20.7
35B 152.6 152.7 152.9 458.2 152.73 76.37 18312.06 380 219.0 20.32
35C 150.9 151.2 151.4 453.5 151.17 75.58 17938.32 350 19.51
36A 151.2 151.3 151.5 454 151.33 75.67 17977.9 360 20.02
36B 152.5 152.6 152.7 457.8 152.6 76.3 18280.11 360 19.69 19.72
36C 153.1 153.2 153.3 459.6 153.2 76.6 18424.14 358 19.43
37A 149.9 149.9 150.1 449.9 149.97 74.98 17654.65 450 25.49
37B 149.8 149.9 150.2 449.9 149.97 74.98 17654.65 409 23.17 24.91
37C 150.2 1512.5 150.6 451.3 150.43 75.22 17764.7 463 26.06
38A 1512.5 150.6 150.7 451.8 150.6 75.3 17804.08 440 24.71
38B 151.5 151.7 152.2 455.4 151.8 75.9 18088.94 472 26.09 25.11
38C 152.5 152.6 153.2 458.3 152.77 76.38 18320.06 449 24.51
39A 152.5 152.7 152.7 457.9 152.63 76.32 18288.09 430 23.51
39B 152.8 152.9 153.1 458.8 152.93 76.47 18360.05 410 22.33 23.67
39C 149.5 149.6 149.7 448.8 149.6 74.8 17568.43 442 25.16
40A 153.4 153.5 153.7 460.6 153.53 76.77 18504.4 452 24.43
40B 1512.5 150.7 150.8 452 150.67 75.33 17819.85 484 27.16 25.19
40C 152.1 152.2 152.3 456.6 152.2 76.1 18184.4 436 23.98
83
Sl. no Dia.1
(mm)
Dia.2
(mm)
Dia.3
(mm)
Sum
dia.
(mm)
Avg.
dia.
(mm)
Radius
(mm)
Area
(mm2)
Load
(KN)
Str.
(Mpa)
Avg.
str.
(Mpa)
41A 153.2 153.3 153.4 459.9 153.3 76.65 18448.2 529 28.67
41B 1512.5 150.7 150.7 451.9 150.63 75.32 17811.96 545 30.6 29.86
41C 149.8 150.2 150.3 450.3 150.1 75.05 17686.06 536 30.31
42A 153.5 153.7 153.8 461 153.67 76.83 18536.55 549 29.62
42B 152.2 152.3 152.4 456.9 152.3 76.15 18208.3 520 28.56 29.13
42C 150.9 151.2 151.4 453.5 151.17 75.58 17938.32 524 29.21
43A 152.5 152.6 152.7 457.8 152.6 76.3 18280.11 504 27.57
43B 147.9 148.3 148.5 444.7 148.23 74.12 17248.9 503 29.16 28.46
43C 148.2 148.4 148.5 445.1 148.37 74.18 17279.94 495 28.65
44A 149.1 149.9 150.2 449.2 149.73 74.87 17599.76 603 34.26
44B 148.2 149.5 149.6 447.3 149.1 74.55 17451.19 610 34.95 34.26
44C 151.2 151.4 151.6 454.2 151.4 75.7 17993.74 604 33.57
45A 152.1 152.2 152.4 456.7 152.23 76.12 18192.37 604 33.2
45B 153.4 152.9 152.9 459.2 153.07 76.53 18392.08 601 32.68 32.93
45C 152.1 152.2 152.4 456.7 152.23 76.12 18192.37 599 32.93
46A 149.9 150.3 150.4 450.6 150.2 75.1 17709.63 490 27.67
46B 150.9 151.2 151.3 453.4 151.13 75.57 17930.41 480 26.77 27.31
46C 152.2 152.4 152.5 457.1 152.37 76.18 18224.25 501 27.49
47A 153.2 152.9 152.9 459 153 76.5 18376.07 589 32.05
47B 152.1 152.2 152.3 456.6 152.2 76.1 18184.4 591 32.5 32.98
47C 147.9 147.8 147.8 443.5 147.83 73.92 17155.94 590 34.39
48A 153.1 153.3 153.4 459.8 153.27 76.63 18440.18 482 26.14
48B 150.8 150.9 150.9 452.6 150.87 75.43 17867.19 475 26.59 26.81
48C 148.2 148.7 148.8 445.7 148.57 74.28 17326.56 480 27.7
84
Sl. no Dia.1
(mm)
Dia.2
(mm)
Dia.3
(mm)
Sum
dia.
(mm)
Avg.
dia.
(mm)
Radius
(mm)
Area
(mm2)
Load
(KN)
Str.
(Mpa)
Avg.
str.
(Mpa)
49A 149.8 150.1 150.2 450.1 150.03 75.02 17670.35 590 33.39
49B 151.3 151.6 151.8 454.7 151.57 75.78 18033.38 628 34.82 34.72
49C 147.4 148.6 148.7 444.7 148.23 74.12 17248.9 620 35.94
50A 149.8 150.1 150.3 450.2 150.07 75.03 17678.2 498 28.17
50B 149.9 150.3 1512.5 450.7 150.23 75.12 17717.49 509 28.73 28.04
50C 151.2 151.4 151.7 454.3 151.43 75.72 18001.66 490 27.22
51A 150.3 150.4 150.7 451.4 150.47 75.23 17772.57 533 29.99
51B 150.9 151.2 151.4 453.5 151.17 75.58 17938.32 656 36.57 34.35
51C 151.1 151.2 151.4 453.7 151.23 75.62 17954.14 655 36.48
52A 152.4 152.6 152.7 457.7 152.57 76.28 18272.12 653 35.74
52B 151.7 151.9 152.2 455.8 151.93 75.97 18120.73 690 38.08 37.74
52C 151.6 151.7 151.8 455.1 151.7 75.85 18065.12 712 39.41
53A 152.4 152.6 152.7 457.7 152.57 76.28 18272.12 691 37.82
53B 154.1 153.5 153.9 461.5 153.83 76.92 18576.79 650 34.99 37.37
53C 150.1 151.2 1512.5 451.8 150.6 75.3 17804.08 700 39.32
54A 150.6 150.7 151.1 452.4 150.8 75.4 17851.4 599 33.55
54B 151.1 151.2 151.4 453.7 151.23 75.62 17954.14 650 36.2 34.44
54C 152.3 152.4 152.5 457.2 152.4 76.2 18232.22 612 33.57
55A 147.1 147.8 147.9 442.8 147.6 73.8 17101.82 290 16.96
55B 148.3 148.5 148.6 445.4 148.47 74.23 17303.25 312 18.03 17.38
55C 148.5 148.6 149.1 446.2 148.73 74.37 17365.46 298 17.16
56A 149.5 149.9 150.2 449.6 149.87 74.93 17631.11 308 17.47
56B 150.1 150.2 150.4 450.7 150.23 75.12 17717.49 280 15.8 16.03
56C 151.5 151.9 151.9 455.3 151.77 75.88 18081 268 14.82
85
Sl. no Dia.1
(mm)
Dia.2
(mm)
Dia.3
(mm)
Sum
dia.
(mm)
Avg.
dia.
(mm)
Radius
(mm)
Area
(mm2)
Load
(KN)
Str.
(Mpa)
Avg.
str.
(Mpa)
57A 152.5 152.9 152.9 458.3 152.77 76.38 18320.06 274 14.96
57B 151.3 151.4 151.6 454.3 151.43 75.72 18001.66 270 15 14.93
57C 150.8 150.9 150.9 452.6 150.87 75.43 17867.19 265 14.83
58A 151.6 151.9 151.9 455.4 151.8 75.9 18088.94 361 19.96
58B 152.9 152.9 153.2 459 153 76.5 18376.07 359 19.54 19.65
58C 150.9 151.2 151.3 453.4 151.13 75.57 17930.41 349 19.46
59A 152.8 152.9 152.9 458.6 152.87 76.43 18344.05 347 18.92
59B 152.2 152.3 152.6 457.1 152.37 76.18 18224.25 350 19.21 19.19
59C 153.1 153.5 153.6 460.2 153.4 76.7 18472.27 359 19.43
60A 150.2 150.3 150.4 450.9 150.3 75.15 17733.22 327 18.44
60B 151.3 151.4 151.5 454.2 151.4 75.7 17993.74 310 17.23 17.45
60C 153.2 153.4 153.5 460.1 153.37 76.68 18464.25 308 16.68
61A 148.2 148.4 148.6 445.2 148.4 74.2 17287.71 313 18.11
61B 150.1 1512.5 150.6 451.2 150.4 75.2 17756.83 382 21.51 19.54
61C 151.2 151.3 151.9 454.4 151.47 75.73 18009.59 342 18.99
62A 151.2 151.4 151.6 454.2 151.4 75.7 17993.74 426 23.67
62B 152.2 152.3 152.4 456.9 152.3 76.15 18208.3 435 23.89 23.34
62C 152.1 152.5 152.8 457.4 152.47 76.23 18248.18 410 22.47
63A 151.7 151.9 152.2 455.8 151.93 75.97 18120.73 320 17.66
63B 150.9 151.2 151.4 453.5 151.17 75.58 17938.32 350 19.51 18.69
63C 151.2 151.4 151.6 454.2 151.4 75.7 17993.74 340 18.9
64A 151.4 151.8 151.9 455.1 151.7 75.85 18065.12 324 17.94
64B 151.9 152.1 152.3 456.3 152.1 76.05 181612.5 315 17.35 17.28
64C 152.1 152.2 152.3 456.6 152.2 76.1 18184.4 301 16.55
86
Sl. no Dia.1
(mm)
Dia.2
(mm)
Dia.3
(mm)
Sum
dia.
(mm)
Avg.
dia.
(mm)
Radius
(mm)
Area
(mm2)
Load
(KN)
Str.
(Mpa)
Avg.
str.
(Mpa)
65A 151.1 151.2 151.4 453.7 151.23 75.62 17954.14 378 21.05
65B 149.2 149.8 150.1 449.1 149.7 74.85 17591.92 391 22.23 21.35
65C 150.2 150.4 150.7 451.3 150.43 75.22 17764.7 369 20.77
66A 149.2 149.5 149.6 448.3 149.43 74.72 17529.3 412 23.5
66B 150.1 150.2 150.6 450.9 150.3 75.15 17733.22 399 22.5 21.79
66C 150.8 151.1 151.2 453.1 151.03 75.52 17906.69 347 19.38
67A 148.1 148.4 148.5 445 148.33 74.17 17272.18 358 20.73
67B 149.8 150.1 150.3 450.2 150.07 75.03 17678.2 378 21.38 20.62
67C 150.1 150.3 150.4 450.8 150.27 75.13 17725.36 350 19.75
68A 151.7 151.8 151.9 455.4 151.8 75.9 18088.94 444 24.55
68B 150.9 151.2 151.3 453.4 151.13 75.57 17930.41 440 24.54 25.26
68C 152.2 152.3 152.4 456.9 152.3 76.15 18208.3 486 26.69
69A 151.2 151.3 151.5 454 151.33 75.67 17977.9 436 24.25
69B 152.1 151.9 151.8 455.8 151.93 75.97 18120.73 473 26.1 25.39
69C 152.2 152.3 152.4 456.9 152.3 76.15 18208.3 470 25.81
70A 151.1 151.2 151.4 453.7 151.23 75.62 17954.14 554 30.86
70B 152.2 152.3 152.4 456.9 152.3 76.15 18208.3 544 29.88 30.68
70C 150.2 150.4 150.6 451.2 150.4 75.2 17756.83 556 31.31
71A 151.2 151.3 151.4 453.9 151.3 75.65 17969.98 482 26.82
71B 150.1 150.4 150.6 451.1 150.37 75.18 17748.96 480 27.04 26.74
71C 151.1 151.2 151.4 453.7 151.23 75.62 17954.14 473 26.34
72A 152.2 152.4 152.6 457.2 152.4 76.2 18232.22 520 28.52
72B 152.2 152.3 152.5 457 152.33 76.17 18216.27 500 27.45 27.93
72C 153.1 152.9 152.9 458.9 152.97 76.48 18368.06 511 27.82
87
Sl. no Dia.1
(mm)
Dia.2
(mm)
Dia.3
(mm)
Sum
dia.
(mm)
Avg.
dia.
(mm)
Radius
(mm)
Area
(mm2)
Load
(KN)
Str.
(Mpa)
Avg.
str.
(Mpa)
73A 152.1 152.3 152.8 457.2 152.4 76.2 18232.22 501 27.48
73B 149.7 149.9 150.1 449.7 149.9 74.95 17638.96 517 29.31 28.21
73C 152.5 152.8 152.9 458.2 152.73 76.37 18312.06 510 27.85
74A 151.1 151.3 151.4 453.8 151.27 75.63 17962.06 518 28.84
74B 152.5 152.3 152.3 457.1 152.37 76.18 18224.25 501 27.49 28.36
74C 153.2 153.3 153.3 459.8 153.27 76.63 18440.18 530 28.74
75A 151.1 151.3 151.4 453.8 151.27 75.63 17962.06 497 27.67
75B 149.4 149.6 149.7 448.7 149.57 74.78 17560.6 437 24.89 26.16
75C 148.9 149.5 149.6 448 149.33 74.67 17505.85 454 25.93
76A 151.9 151.9 152.2 456 152 76 18136.64 595 32.81
76B 150.9 151.4 151.6 453.9 151.3 75.65 17969.98 590 32.83 32.44
76C 153.1 153.4 153.2 459.7 153.23 76.62 18432.16 584 31.68
77A 150.1 150.3 150.4 450.8 150.27 75.13 17725.36 582 32.83
77B 151.2 151.4 151.5 454.1 151.37 75.68 17985.82 591 32.86 32.74
77C 149.9 150.2 1512.5 450.6 150.2 75.1 17709.63 576 32.52
78A 1512.5 150.9 151.2 452.6 150.87 75.43 17867.19 530 29.66
78B 149.9 1512.5 150.6 451 150.33 75.17 17741.09 537 30.27 29.5
78C 151.1 150.7 150.7 452.5 150.83 75.42 17859.3 510 28.56
79A 149.9 150.1 150.2 450.2 150.07 75.03 17678.2 548 31
79B 149.7 149.9 150.1 449.7 149.9 74.95 17638.96 530 30.05 31.7
79C 151.2 151.3 151.5 454 151.33 75.67 17977.9 612 34.04
80A 152.2 152.4 152.5 457.1 152.37 76.18 18224.25 470 25.79
80B 150.2 1512.5 150.9 451.6 1512.53 75.27 17788.32 468 26.31 27.05
80C 153.2 153.5 153.6 460.3 153.43 76.72 18480.3 537 29.06
88
Sl. no Dia.1
(mm)
Dia.2
(mm)
Dia.3
(mm)
Sum
dia.
(mm)
Avg.
dia.
(mm)
Radius
(mm)
Area
(mm2)
Load
(KN)
Str.
(Mpa)
Avg.
str.
(Mpa)
81A 153.2 153.5 153.9 460.6 153.53 76.77 18504.4 600 32.42
81B 153.1 153.5 153.6 460.2 153.4 76.7 18472.27 640 34.65 34.1
81C 152.2 152.4 152.9 457.5 152.5 76.25 18256.16 643 35.22
82A 152.4 152.3 152.3 457 152.333 76.17 18216.27 174 9.552
82B 151.8 152.2 152.3 456.3 152.1 76.05 181612.5 171 9.416 9.347
82C 151.9 152.4 152.3 456.6 152.2 76.1 18184.4 165 9.074
82D 151.5 151.8 151.9 455.2 151.733 75.87 18073.06 307 16.99
82E 152.2 152.4 152.4 457 152.333 76.17 18216.27 332 18.23 17.22
82F 152.1 151.9 151.9 455.9 151.967 75.98 18128.69 298 16.44
82G 152.5 153.8 153.9 460.2 153.4 76.7 18472.27 389 21.06
82H 152.6 152.9 152.9 458.4 152.8 76.4 18328.05 382 20.84 21.14
82I 152.8 153.2 153.3 459.3 153.1 76.55 18400.09 396 21.52
82J 149.9 1512.5 150.6 451 150.333 75.17 17741.09 435 24.52
82K 152.1 152.3 152.4 456.8 152.267 76.13 18200.33 491 26.98 25.55
82L 148.3 148.7 148.9 445.9 148.633 74.32 17342.12 436 25.14
82M 152 152.2 152.2 456.4 152.133 76.07 18168.47 584 32.14
82N 151.8 151.9 152 455.7 151.9 75.95 18112.78 560 30.92 31.4
82O 149.9 150 150.2 450.1 150.033 75.02 17670.35 550 31.13
82P 150.2 150.4 1512.5 451.1 150.367 75.18 17748.96 615 34.65
82Q 152.1 152.4 152.6 457.1 152.367 76.18 18224.25 620 34.02 34.48
82R 151.2 151.3 151.5 454 151.333 75.67 17977.9 625 34.76
83A 151.7 151.9 152.3 455.9 151.967 75.98 18128.69 126 6.95
83B 151.5 151.9 152.2 455.6 151.867 75.93 18104.84 128 7.07 7.236
83C 152.1 152.4 152.4 456.9 152.3 76.15 18208.3 140 7.689
83D 149.7 149.9 149.9 449.5 149.833 74.92 17623.27 254 14.41
83E 150.8 151.2 151.3 453.3 151.1 75.55 17922.5 298 16.63 15.55
83F 151.9 150.8 150.8 453.5 151.167 75.58 17938.32 280 15.61
83G 151.8 152.1 152.1 456 152 76 18136.64 338 18.64
83H 152 152 152.4 456.4 152.133 76.07 18168.47 290 15.96 17.25
89
Sl. no Dia.1
(mm)
Dia.2
(mm)
Dia.3
(mm)
Sum
dia.
(mm)
Avg.
dia.
(mm)
Radius
(mm)
Area
(mm2)
Load
(KN)
Str.
(Mpa)
Avg.
str.
(Mpa)
83I 149.5 149.7 149.9 449.1 149.7 74.85 17591.92 302 17.17
83J 151.2 151.4 151.5 454.1 151.367 75.68 17985.82 480 26.69
83K 150.8 151.2 151.3 453.3 151.1 75.55 17922.5 452 25.22 25.43
83L 148.9 150.3 150.4 449.6 149.867 74.93 17631.11 430 24.39
83M 152.6 152.7 152.8 458.1 152.7 76.35 18304.07 540 29.5
83N 149.7 149.9 150.1 449.7 149.9 74.95 17638.96 568 32.2 30.67
83O 148.9 149.4 149.4 447.7 149.233 74.62 17482.41 530 30.32
83P 152.2 152.5 152.8 457.5 152.5 76.25 18256.16 600 32.87
83Q 152.3 152.5 152.6 457.4 152.467 76.23 18248.18 610 33.43 33
83R 152.1 152.3 152.4 456.8 152.267 76.13 18200.33 595 32.69
84A 151.6 151.1 151.1 453.8 151.267 75.63 17962.06 232 12.92
84B 151.7 152.8 151.7 456.2 152.067 76.03 18152.55 204 11.24 12.04
84C 148.2 148.6 147.4 444.2 148.067 74.03 17210.13 206 11.97
84D 151.5 150.7 150.9 453.1 151.033 75.52 17906.69 366 20.44
84E 152.2 152.3 152.3 456.8 152.267 76.13 18200.33 367 20.16 20.67
84F 152.1 152.4 152.5 457 152.333 76.17 18216.27 390 21.41
84G 152.9 153 153 458.9 152.967 76.48 18368.06 457 24.88
84H 152.4 152.9 152.9 458.2 152.733 76.37 18312.06 451 24.63 24.54
84I 148.9 149.2 149.4 447.5 149.167 74.58 17466.8 421 24.1
84J 151.1 151.4 151.6 454.1 151.367 75.68 17985.82 501 27.86
84K 148.9 149.2 149.4 447.5 149.167 74.58 17466.8 502 28.74 28.24
84L 151.1 151.4 151.6 454.1 151.367 75.68 17985.82 506 28.13
84M 149.7 149.9 150.1 449.7 149.9 74.95 17638.96 625 35.43
84N 1512.5 150.6 150.9 452 150.667 75.33 17819.85 580 32.55 33.94
84O 149.9 150.1 150.1 450.1 150.033 75.02 17670.35 598 33.84
84P 150.1 150.2 150.3 450.6 150.2 75.1 17709.63 660 37.27
84Q 150.4 1512.5 150.6 451.5 1512.5 75.25 17780.45 640 35.99 35.59
84R 152.1 152.2 152.5 456.8 152.267 76.13 18200.33 610 33.52
(a)
(d)
(g)
10
15
20
25
30
35
40
45
0.3 0.4 0.5 0.6 0.7
Com
pre
ssiv
e st
rength
, f'c
( M
Pa
)
Water / cement ratio ( by weight )
( Max size = 12.5 mm , A / C ratio = 3.0 )
CA/FA ratio = 1.5
CA/FA ratio = 2.0
CA/FA ratio = 2.5
10
15
20
25
30
35
40
45
0.3 0.4 0.5 0.6 0.7
Com
pre
ssiv
e st
rength
, f'c
( M
Pa
)
Water / cement ratio ( by weight )
( Max size = 19 mm , A / C ratio = 3.0 )
CA/FA ratio = 1.5
CA/FA ratio = 2.0
CA/FA ratio = 2.5
10
15
20
25
30
35
40
45
0.3 0.4 0.5 0.6 0.7
Com
pre
ssiv
e s
trength
, f
'c (
MP
a)
Water / cement ratio ( by weight )
( Max size = 25 mm , A / C ratio = 3.0 )
CA/FA ratio = 1.5
CA/FA ratio = 2.0
CA/FA ratio = 2.5
Fig. B.1 Influence of water/cement ratio on compressive strength of 90
(b)
(e)
(h)
10
15
20
25
30
35
40
45
0.3 0.4 0.5 0.6 0.7
Com
pre
ssiv
e st
rength
, f'c
( M
Pa
)
Water / cement ratio ( by weight )
( Max size = 12.5 mm , A / C ratio = 4.5 )
CA/FA ratio = 1.5
CA/FA ratio = 2.0
CA/FA ratio = 2.5
10
15
20
25
30
35
40
45
0.3 0.4 0.5 0.6 0.7
Com
pre
ssiv
e st
rength
, f'c
( M
Pa
)
Water / cement ratio ( by weight )
( Max size = 19 mm , A / C ratio = 4.5 )
CA/Fa ratio = 1.5
CA/FA ratio = 2.0
CA/FA ratio = 2.5
10
15
20
25
30
35
40
45
0.3 0.4 0.5 0.6 0.7
Com
pre
ssiv
e st
rength
, f
'c (
MP
a )
Water / cement ratio ( by weight )
( Max size = 25 mm , A / C ratio = 4.5 )
CA/FA ratio = 1.5
CA/FA ratio = 2.0
CA/FA ratio = 2.5
10
15
20
25
30
35
40
45
0.3
Com
pre
ssiv
e st
rength
, f'c
( M
Pa
)
10
15
20
25
30
35
40
45
0.3
Com
pre
ssiv
e st
rength
, f'c
( M
Pa
)
10
15
20
25
30
35
40
45
0.3
Com
pre
ssiv
e st
rength
, f'c
( M
Pa
)
1 Influence of water/cement ratio on compressive strength of concrete
(c)
(f)
(j)
0.4 0.5 0.6 0.7
Water / cement ratio ( by weight )
( Max size = 12.5 mm , A / C ratio = 6.0 )
CA/FA ratio = 1.5
CA/FA ratio = 2.0
CA/FA ratio = 2.5
0.4 0.5 0.6 0.7
Water / cement ratio ( by weight )
( Max size = 19 mm ,A / C ratio = 6.0 )
CA/FA ratio = 1.5
CA/FA ratio = 2.0
CA/FA ratio = 2.5
0.4 0.5 0.6 0.7Water / cement ratio ( by weight )
( Max size = 25 mm , A / C ratio = 6.0 )
CA/FA ratio = 1.5
CA/FA ratio = 2.0
CA/FA ratio = 2.5
(a)
(d)
(g)
10
15
20
25
30
35
40
45
2 3 4 5 6
Com
pre
ssiv
e st
rength
, f'c
( M
pa
)
A / C ratio ( by volume )
( Max CA size = 12.5 mm , W / C = 0.40 )
CA/FA=1.5
CA/FA=2.0
CA/FA=2.5
10
15
20
25
30
35
40
45
2 3 4 5 6
Com
pre
ssiv
e st
rength
, f
'c
( M
pa
)
A / C ratio ( by volume )
( Max CA size = 19.0 mm , W / C = 0.40 )
CA/FA=1.5
CA/FA=2.0
CA/FA=2.5
10
15
20
25
30
35
40
45
2 3 4 5 6
Com
pre
ssiv
e st
rength
, f'c
( M
pa
)
A / C ratio ( by volume )
( Max CA size = 25 mm , W / C = 0.40 )
CA/FA=1.5
CA/FA= 2.0
CA/FA=2.5
Fig. B.2 Influence of aggregate/cement ratio on compressive strength of concrete91
(b)
(e)
(h)
10
15
20
25
30
35
40
45
2 3 4 5 6 7
Com
pre
ssiv
e st
rength
, f'c
(
Mpa
)
A / C ratio ( by volume )
( Max CA size = 12.5mm , W / C = 0.50 )
CA/FA=1.5
CA/FA=2.0
CA/FA=2.5
10
15
20
25
30
35
40
45
2 3 4 5 6
Com
pre
ssiv
e st
rength
, f'c
(
Mpa
)
A / C ratio ( by volume )
( Max CA size = 19 mm , W / C = 0.50 )
CA/FA=1.5
CA/FA=2.0
CA/FA=2.5
10
15
20
25
30
35
40
45
2 3 4 5 6
Com
pre
ssiv
e st
rength
, f'c
(
Mpa
)
A / C ratio ( by volume )
( Max CA size = 25.0 mm , W / C = 0.50 )
CA/FA=1.5
CA/FA=2.0
CA/FA=2.5
10
15
20
25
30
35
40
45
2
Com
pre
ssiv
e st
rength
, f'c
( M
pa
)
10
15
20
25
30
35
40
45
2
Com
pre
ssiv
e st
rength
, f'c
( M
pa
)
10
15
20
25
30
35
40
45
2
Com
pre
ssiv
e st
rength
, f'c
( M
pa
)
2 Influence of aggregate/cement ratio on compressive strength of concrete
(c)
(f)
(i)
3 4 5 6
A / C ratio ( by volume )
( Max CA size = 12.5 mm , W / C = 0.60 )
CA/FA=0.60
CA/FA=2.0
CA/FA=2.5
2.5 3 3.5 4 4.5 5 5.5 6 6.5
A / C ratio ( by volume )
( Max CA size = 19.0 mm , W / C = 0.60 )
CA/FA=1.5
CA/FA=2.0
CA/FA=2.5
3 4 5 6
A / C ratio ( by volume )
( Max CA size = 25.0 mm , W / C = 0.60 )
CA/FA=1.5
CA/FA=2.0
CA/FA=2.5
2 Influence of aggregate/cement ratio on compressive strength of concrete
(a)
(d)
(g)
10
15
20
25
30
35
40
45
1 1.5 2 2.5 3
Com
pre
ssiv
e st
rength
, f'c
(
MP
a )
CA / FA ratio
( Max size = 12.5 mm , w / c = 0.40 )
A/C ratio= 6.0
A/C ratio= 4.5
A/C ratio= 3.0
10
15
20
25
30
35
40
45
1 1.5 2 2.5 3
Com
pre
ssiv
e st
rength
, f'c
( M
Pa
)
CA / FA ratio
( Max size = 19.0 mm , w / c = 0.40 )
A/C ratio= 6.0
A/C ratio= 4.5
A/C ratio= 3.0
10
15
20
25
30
35
40
45
1 1.5 2 2.5 3
Com
pre
ssiv
e st
rength
, f'c
( M
Pa
)
CA / FA ratio
( Max size = 25 mm , w / c = 0.40 )
A/C ratio= 6.0
A/C ratio= 4.5
A/C ratio= 3.0
Fig. B.3 Influence of coarse aggregate/fine aggregate ratio on 92
(b)
(e)
(h)
10
15
20
25
30
35
40
45
1 1.5 2 2.5 3
Com
pre
ssiv
e st
rength
, f'c
( M
Pa
)
CA / FA ratio
( Max size = 12.5 mm , w / c = 0.50 )
A/C ratio= 6.0
A/C ratio= 4.5
A/C ratio= 3.0
10
15
20
25
30
35
40
45
1 1.5 2 2.5 3
Com
pre
ssiv
e st
rength
, f'c
(
MP
a )
CA / FA ratio
( Max size = 19 mm , w / c = 0.5 )
A/C ratio= 6.0
A/C ratio= 4.5
A/C ratio= 3.0
10
15
20
25
30
35
40
45
1 1.5 2 2.5 3
Com
pre
ssiv
e st
rength
, ,f
'c
( M
Pa)
CA / FA ratio
(Max size = 25 mm , w / c = 0.50 )
A/C ratio= 6.0
A/C ratio= 4.5
A/C ratio= 3.0
10
15
20
25
30
35
40
45
1
Com
pre
ssiv
e st
rength
, f'c
( M
Pa
)
10
15
20
25
30
35
40
45
1
Com
pre
ssiv
e st
rength
, f'c
(
MP
a )
10
15
20
25
30
35
40
45
1
Com
pre
ssiv
e st
rength
, f'c
(
Mpa
)
3 Influence of coarse aggregate/fine aggregate ratio on compressive strength of concrete
(c)
(f)
(i)
1.5 2 2.5 3CA / FA ratio
(Max size = 12.5 mm ,w / c = 0.60 )
A/C ratio= 6.0
A/C ratio= 4.5
A/C ratio= 3.0
1.5 2 2.5 3CA / FA ratio
( Max size = 19 mm , w / c = 0.60 )
A/C ratio= 6.0
A/C ratio= 4.5
A/C ratio= 3.0
1.5 2 2.5 3
CA / FA ratio
( Max size = 25 mm , w / c = 0.60 )
A/C ratio= 6.0
A/C ratio= 4.5
A/C ratio= 3.0
compressive strength of concrete
(a)
(d)
(g)
10
15
20
25
30
35
40
45
10 15 20 25 30
Com
pre
ssiv
e st
rength
, f
'c
( M
Pa
)
Maximum size of CA (mm)
( W / C = 0.40 , CA / FA = 1.5 )
A/C ratio= 3.0
A/C ratio= 6.0
A/C ratio= 4.5
10
15
20
25
30
35
40
45
10 15 20 25 30
Com
pre
ssiv
e st
rength
, f
'c
( M
Pa
)
Maximum size of CA (mm)
( W / C = 0.40 , CA / FA = 2.0 )
A/C ratio= 6.0
A/C ratio= 4.5
A/C ratio= 3.0
10
15
20
25
30
35
40
45
10 15 20 25 30
Com
pre
ssiv
e st
rength
, f
'c
( M
Pa
)
Maximum size of CA (mm)
( W / C = 0.40 , CA / FA = 2.5 )
A/C ratio= 6.0
A/C ratio= 4.5
A/C ratio= 3.0
Fig. B.4 Influence of maximum size of CA (mm) on compressive strength of concrete93
(b)
(e)
(h)
10
15
20
25
30
35
40
45
10 15 20 25 30
Com
pre
ssiv
e st
rength
, f
'c
( M
Pa
)
Maximum size of CA (mm)
( W / C = 0.50 , CA / FA = 1.5 )
A/C ratio= 6.0
A/C ratio= 4.5
A/C ratio= 3.0
10
15
20
25
30
35
40
45
10 15 20 25 30
Com
pre
ssiv
e st
rength
, f
'c (
MP
a )
Maximum size of CA (mm)
( W / C = 0.50 , CA / FA = 2.0 )
A/C ratio= 6.0
A/C ratio= 4.5
A/C ratio= 3.0
10
15
20
25
30
35
40
45
10 15 20 25 30
Com
pre
ssiv
e st
rength
, f
'c
( M
Pa
)
Maximum size of CA (mm)
( W / C = 0.50 , CA / FA = 2.5 )
A/C ratio= 6.0
A/C ratio= 4.5
A/C ratio= 3.0
10
15
20
25
30
35
40
45
10
Com
pre
ssiv
e st
rength
, f
'c
( M
Pa
)
10
15
20
25
30
35
40
45
10
Com
pre
ssiv
e st
rength
, f
'c
( M
Pa
)
10
15
20
25
30
35
40
45
10
Com
pre
ssiv
e st
rength
, f
'c
( M
Pa
)
4 Influence of maximum size of CA (mm) on compressive strength of concrete
(c)
(f)
(i)
15 20 25 30
Maximum size of CA (mm)
( W / C = 0.60 , CA / FA = 1.5 )
A/C ratio = 6.0
A/C ratio = 4.5
A/C ratio = 3.0
15 20 25 30
Maximum size of CA (mm)
( W / C= 0.60 , CA / FA = 2.0 )
A/C ratio= 6.0
A/C ratio= 4.5
A/C ratio= 3.0
15 20 25 30
Maximum size of CA (mm)
( W / C = 0.60 , CA / FA = 2.5 )
A/C ratio = 6.0
A/C ratio = 4.5
A/C ratio= 3.0
4 Influence of maximum size of CA (mm) on compressive strength of concrete
94
