High Performance Concrete

HIGH PERFORMANCE CONCRETE GRADE M50

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CHAPTER – 1

1. INTRODUCTION

Concrete is a durable and versatile construction material. It is not only

Strong, economical and takes the shape of the form in which it is placed, but it is also

aesthetically satisfying. However experience has shown that concrete is vulnerable to

deterioration, unless precautionary measures are taken during the design and production. For

this we need to understand the influence of components on the behavior of concrete and to

produce a concrete mix within closely controlled tolerances.

The conventional Portland cement concrete is found deficient in respect of :

Durability in severe environs (shorter service life and frequent

maintenance)

Time of construction (slower gain of strength)

Energy absorption capacity (for earthquake resistant structures)

Repair and retrofitting jobs.

Hence it has been increasingly realized that besides strength, there are other

equally important criteria such as durability, workability and toughness. And hence we talk

about ‘High performance concrete’ where performance requirements can be different than

high strength and can vary from application to application.

High Performance Concrete can be designed to give optimized performance

characteristics for a given set of load, usage and exposure conditions consistent with the

requirements of cost, service life and durability. The high performance concrete does not

require special ingredients or special equipments except careful design and production. High

performance concrete has several advantages like improved durability characteristics and

much lesser micro cracking than normal strength concrete.


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1.1 DEFINITION

Any concrete which satisfies certain criteria proposed to overcome limitations of

conventional concretes may be called High Performance Concrete. It may include concrete,

which provides either substantially improved resistance to environmental influences or

substantially increased structural capacity while maintaining adequate durability. It may also

include concrete, which significantly reduces construction time to permit rapid opening or

reopening of roads to traffic, without compromising long-term servicibility. Therefore it is

not possible to provide a unique definition of High Performance Concrete without

considering the performance requirements of the intended use of the concrete.

American Concrete Institute defines High Performance Concrete as

“A concrete which meets special performance and uniformity requirements that cannot

always be achieved routinely by using only conventional materials and normal mixing,

placing and curing practices”. The requirements may involve enhancements of characteristics

such as placement and compaction without segregation, long-term mechanical properties, and

early age strength or service life in severe environments. Concretes possessing many of these

characteristics often achieve High Strength, but High Strength concrete may not necessarily

be of High Performance .A classification of High Performance Concrete related to strength is

shown below.

Table no.1. classification of High Performance Concrete related to strength

Compressive

strength (Mpa)

50 75 100 125 150

High Performance

Class

I II III IV V


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CHAPTER – 2

2. SELECTION OF MATERIALS

The production of High Performance Concrete involves the following three

important interrelated steps:

Selection of suitable ingredients for concrete having the desired rheological

properties, strength etc

Determination of relative quantities of the ingredients in order to produce durability.

Careful quality control of every phase of the concrete making process.

The main ingredients of High Performance Concrete are

2.1 CEMENT (opc)

Physical and chemical characteristics of cement play a vital role in developing

strength and controlling rheology of fresh concrete. Fineness affects water requirements for

consistency. When looking for cement to be used in High Performance Concrete one should

choose cement containing as little C3A as possible because the lower amount of C3A, the

easier to control the rheology and lesser the problems of cement-super plasticizer

compatibility. Finally from strength point of view, this cement should be finally ground and

contain a fair amount of C3S.

2.1.1 FLY ASH CEMENT

Fly ash was historically known as pulverized fuel ash in the UK, it is a by-product

from the burning of pulverized coal in power stations. It has both pozzolanic and physical

properties that enhance the performance of cement. When Portland cement hydrates it

produces alkali calcium hydroxide (lime). Pozzolanas such as fly ash can react with this

lime to form stable calcium silicate and aluminate hydrates. These hydrates fill the voids

within the mortar matrix, thus reducing the permeability and the potential for

efflorescence. Additionally, the reduction in the quantity of lime remaining further

decreases the occurance of efflorescence. This process improves the strength, durability,

chloride and sulfate resistance of the concrete.


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Fly ash cement have improved fresh properties, in particular, cohesion and

resistance to segregation and bleeding. Furthermore, they will tend to have a slower

setting time which is advantageous in warmer weather conditions.

2.1.2 GGBS CEMENT

Ground granulated blast furnace slag is classified as a latent hydraulic material.

This means that it has inherent cementious properties, but these have to be activated. The

normal means of achieving this is to combine the material with Portland cement. During

the manufacture of iron, blast furnace slag is produced as a by-product. This material is

rapidly cooled to form a granulate and then ground to a fine white powder (ggbs), which

has many similar characteristics to Portland cement. When ggbs is blended with Portland

cement further recognized cementitious materials such as Portland-slag cement and blast

furnace cement are produced.

Table.2 Typical Chemical oxides of various cementitious materials

Portland cement Slag cement Fly ash cement

CaO 65 45 25

Sio2 20 33 37

Al2O3 4 10 16

Fe2O3 3 1 7

MgO 3 6 7

2.2 FINE AGGREGATE

Both river sand and crushed stones may be used. Coarser sand may be preferred

as finer sand increases the water demand of concrete and very fine sand may not be essential

in High Performance Concrete as it usually has larger content of fine particles in the form of

cement and mineral admixtures such as fly ash, etc. The sand particles should also pack to

give minimum void ratio as the test results show that higher void content leads to

requirement of more mixing water.


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2.3 COARSE AGGREGATE

The coarse aggregate is the strongest and least porous component of concrete.

Coarse aggregate in cement concrete contributes to the heterogeneity of the cement concrete

and there is weak interface between cement matrix and aggregate surface in cement concrete.

This results in lower strength of cement concrete by restricting the maximum size of

aggregate and also by making the transition zone stronger. By usage of mineral admixtures,

the cement concrete becomes more homogeneous and there is marked enhancement in the

strength properties as well as durability characteristics of concrete. The strength of High

Performance Concrete may be controlled by the strength of the coarse aggregate, which is

not normally the case with the conventional cement concrete. Hence, the selection of coarse

aggregate would be an important step in High Performance Concrete design mix.

2.4 WATER

Water is an important ingredient of concrete as it actively participates in the

chemical reactions with cement. The strength of cement concrete comes mainly from the

binding action of the hydrated cement gel. The requirement of water should be reduced to

that required for chemical reaction of unhydrated cement as the excess water would end up in

only formation of undesirable voids in the hardened cement paste in concrete. From High

Performance Concrete mix design considerations, it is important to have the compatibility

between the given cement and the chemical/mineral admixtures along with the water used for

mixing.

2.5 CHEMICAL ADMIXTURES

Chemical admixtures are the essential ingredients in the concrete mix, as they

increase the efficiency of cement paste by improving workability of the mix and there by

resulting in considerable decrease of water requirement.

Different types of chemical admixtures are

Plasticizers


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Super plasticizers

Retarders

Air entraining agents

Placticizers and super placticizers help to disperse the cement particles in the mix and

promote mobility of the concrete mix. Retarders help in reduction of initial rate of hydration

of cement, so that fresh concrete retains its workability for a longer time. Air entraining

agents artificially introduce air bubbles that increase workability of the mix and enhance the

resistance to deterioration due to freezing and thawing actions.

2.6 MINERAL ADMIXTURES

The major difference between conventional cement concrete and High

Performance Concrete is essentially the use of mineral admixtures in the latter. Some of the

mineral admixtures are

Fly ash

GGBS (Ground Granulated Blast Furnace Slag)

Silica fume

Carbon black powder

Anhydrous gypsum based mineral additives

Mineral admixtures like fly ash and silica fume act as puzzolonic materials as well as fine

fillers, thereby the microstructure of the hardened cement matrix becomes denser and

stronger. The use of silica fume fills the space between cement particles and between

aggregate and cement particles. It is worth while noting that addition of silica fume to the

concrete mix does not impart any strength to it, but acts as a rapid catalyst to gain the early

age strength.


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CHAPTER – 3

3. BEHAVIOUR OF FRESH CONCRETE

The behavior of fresh High Performance Concrete is not substantially different

from conventional concretes. While many High Performance Concretes exhibits rapid

stiffening and early strength gain, other’s may have long set times and low early strengths.

Workability is normally better than conventional concretes produced from the same set of

raw materials. Curing is not fundamentally different for High Performance Concrete than for

conventional concretes although many High Performance Concretes with good early strength

characteristics may be less sensitive to curing.

3.1 WORKABILITY

The workability of High Performance Concrete is normally good, even at low

slumps, and High Performance Concrete typically pumps very well, due to the ample volume

cementitious materials and the presence if chemical admixtures. High Performance Concrete

has been successfully pumped even up to 80 storeys. While pumping of concrete, one should

have a contingency plan for pump breakdown. Super workable concretes have the ability to

fill the heavily reinforced sections without internal or external vibration, without segregation

and without developing large sized voids. These mixtures are intended to be self-leveling and

the rate of flow is an important factor in determining the rate of production and placement

schedule. It is also a useful tool in assessing the quality of the mixture. Flowing concrete is,

of course, not required in all High Performance Concrete and adequate workability is

normally not difficult to attain.


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3.2 SETTING TIME

Setting time can vary dramatically depending on the application and the presence

of set modifying admixtures and percentage of the paste composed of Portland cement.

Concretes for applications with early strength requirements can lead to mixtures with rapid

slump loss and reduced working time. This is particularly true in warmer construction

periods and when the concrete temperature has been kept high to promote rapid strength

gain.

The use of large quantities of water reducing admixtures can significantly extend

setting time and therefore reduce very early strengths even though strengths at more than 24

hours may be relatively high. Dosage has to be monitored closely with mixtures containing

substantial quantities of mineral admixtures so as to not overdose the Portland cement if

adding the chemical admixture on the basis of total cementitious material.


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CHAPTER - 4

4. BEHAVIOUR OF HARDENED CONCRETE

The behavior of hardened concrete can be characterized in terms of it’s short

term and long term properties. Short-term properties include strength in compression,

tension and bond. The long-term properties include creep, shrinkage, behaviour under

fatigue and durability characteristics such as porosity, permeability, freeze-thaw resistance

and abrasion resistance.

4.1 STRENGTH

The strength of concrete depends on a number of factors including the properties and

proportions of the constituent materials, degree of hydration, rate of loading, method of

testing and specimen geometry. The properties of the constituent materials affect the

strength are the quality of fine and coarse aggregate, the cement paste and the bond

characteristics. Hence, in order to increase the strength steps must be taken to strengthen

these three sources.

Testing conditions including age, rate of loading, method of testing and specimen

geometry significantly influence the measured strength. The strength of saturated specimens

can be 15 to 20 percent lower than that of dry specimens. Under impact loading, strength

may be as much as 25 to 35 percent higher than under a normal rate of loading. Cube

specimens generally exhibit 20 to 25 percent higher strengths than cylindrical specimens.

Larger specimens exhibit lower average strengths.

4.1.1 STRENGTH DEVELOPMENT

The strength development with time is a function of the constituent materials and

curing techniques. An adequate amount of moisture is necessary to ensure that hydration is

sufficient to reduce the porosity to a level necessary to attain the desired strength. Although

cement paste in practice will never completely hydrate, the aim of curing is to ensure


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sufficient hydration. In general, a higher rate of strength gain is observed for higher strength

concrete at early ages. At later ages the difference is not significant.

4.2 COMPRESSIVE STRENGTH

Maximum practically achievable, compressive strengths have increased steadily

over the years. Presently,28 days strength of up to 80Mpa are obtainable. However, it has

been reported that concrete with 90-day cylinder strength of 130 Mpa has been used in

buildings in US. The trend for the future as identified by the ACI committee is to develop

concrete with compressive strength in excess of 140 Mpa and identify its appropriate

applications.

4.3 TENSILE STRENGTH

The tensile strength governs the cracking behavior and affects other properties

such as stiffness; damping action, bond to embedded steel and durability of concrete. It is

also of importance with regard to the behavior of concrete under shear loads. The tensile

strength is determined either by direct tensile tests or by indirect tensile tests such as split

cylinder tests.

4.4 DURABILITY CHARACTERISTICS

The most important property of High Performance Concrete, distinguishing it from

conventional cement concrete is it’s far higher superior durability. This is due to the

refinement of pore structure of microstructure of the cement concrete to achieve a very

compact material with very low permeability to ingress of water, air, oxygen, chlorides,

sulphates and other deleterious agents. Thus the steel reinforcement embedded in High

Performance Concrete is very effectively protected. As far as the resistance to freezing and

thawing is concerned, several aspects of High Performance Concrete should be considered.

First, the structure of hydrated cement paste is such that very little freezable water is present.

Second, entrained air reduces the strength of high performance concrete because the


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improvement in workability due to the air bubbles cannot be fully compensated by a

reduction in the water content in the presence of a superplasticizer. In addition, air

entrainment at very low water/cement ratio is difficult. It is, therefore, desirable to establish

the maximum value of the water/cement ratio below which alternating cycles of freezing and

thawing do not cause damage to the concrete. The abrasion resistance of High Performance

Concrete is very good, not only because of high strength of the concrete but also because of

the good bond between the coarse aggregate and the matrix which prevents differential wear

of the surface. On the other hand, High Performance Concrete has a poor resistance to fire

because the very low permeability of High Performance Concrete does not allow the egress

of steam formed from water in the hydrated cement paste. The absence of open pores in the

structure zone of High Performance Concrete prevents growth of bacteria. Because of all the

above- reasons, High Performance Concrete is said to have better durability characteristics

when compared to conventional cement concrete.

4.5 WHEN TO USE HPC

High Performance Concrete can be used in severe exposure conditions where

there is a danger to concrete by chlorides or sulphates or other aggressive agents as they

ensure very low permeability. High Performance Concrete is mainly used to increase the

durability is not just a problem under extreme conditions of exposure but under normal

circumstances also, because carbon di oxide is always present in the air .This results in

carbonation of concrete which destroys the reinforcement and leads to corrosion.

Aggressive salts are sometimes present in the soil, which may cause abrasion. High

Performance Concrete can be used to prevent deterioration of concrete. Deterioration of

concrete mostly occurs due to alternate periods of rapid wetting and prolonged drying with

a frequently alternating temperatures. Since High Performance Concrete has got low

permeability it ensures long life of a structure exposed to such conditions.


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CHAPTER - 5

5. TEST CONDUCTED ON INGREDIENTS

5.1 COARSE AGGREGATE (CA)

a) Water absorption test on coarse aggregate

Weight of aggregate before testing (W1) =1000gm

Weight of the coarse aggregate after surface drying (W2) =1000gm

= ((W2-W1)/W1)X100

= ((1000-1000)/1000)X100

= 0 %

b) Specific gravity of coarse aggregate

Weight of empty pyconometer bottle (W1) = 450 gm

Weight of pyconometer bottle+coarse aggregate (W2) = 664 gm

Weight of pyconometer bottle+coarse aggregate+water (W3) = 1550 gm

Weight of pyconometer bottle+water (W4) = 1280 gm

= ((W2-W1)/(W2-W1)-(W3-W4))

= ((664-450)/(664-450)-(1550-1280))

G = 2.61


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5.2 FINE AGGREGATE (FA)

a) Water absorption test on fine aggregate

Weight of the fine aggregate before testing (W1) =1000 gm

Weight of the fine aggregate after surface drying (W2) =2979 gm

So the absorption of fine aggregate

= ((W2-W1)/W1)X100

= ((3000-2979)/(3000))X100

= 0.7%

b) Specific gravity test on fine aggregate

Weight of empty pyconomater bottle (W1) = 450 gm

Weight of pyconometer bottle+fine aggregate (W2) = 781 gm

Weight of pyconometer bottle+fine aggregate+water (W3) = 1490 gm

Weight of pyconometer bottle+water (W4 ) = 1280 gm

= ((W2-W1)/(W2-W1)-(W3-W4))

= ((781-450)/(781-450)-(1490-1280)

G = 2.73


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5.3 SPECIFIC GRAVITY TEST OF CEMENT

a) Cement (OPC)

Weight of the empty gravity bottle (W1) = 30 gm

Weight of empty gravity bottle +cement (W2) = 46 gm

Weight of the gravity bottle + cement + kerosene (W3) = 87 gm

Weight of the gravity bottle +water (W4) = 76 gm

= ((W2-W1)/(W2-W1)-(W3-W4))

= ((46-30)/(42-30)-(87-76))

G = 3.15

b) Cement (SLAG)




Weight of the gravity bottle +water (W4) = 76 gm

= ((W2-W1)/(W2-W1)-(W3-W4))

= ((47-30)/(47-30)-(87-76))

G = 2.9


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c) Cement (FLYASH)




Weight of the gravity bottle +water (W4) =76 gm

= ((W2-W1)/(W2-W1)-(W3-W4))

= ((49-30)/(49-30)-(87-76))

G = 2.37


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5.4 SIEVE ANALYSIS FOR COMBINED 20MM & 10MM

AGGREGATES

Table.3

SIEVE SIZE 20 MM 10 MM 4.75 MM PAN

20 mm graded

aggregate

49.46 8.40 0.22 -

10 mm graded

aggregate 45 40.20 0.90 -

Total % of

passing

95.45 48.60 1.12 -

Requirements 95-100 25-55 0-10 0

5.5 SAND TEST: SPECIFICATIONS FOR GRADATION OF NATURAL

SAND (IS 383-1970)

Table.3.1

Sieve sizes Zone ii

(in %)

10 mm 100

4.75 mm 90-100

2.36 mm 75-100

1.18 mm 55-90

600 micron 35-59

300 micron 8-30

150 micron 0-10


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5.6 AGGREGATE IMPACT VALUE TEST

Table.3.2

Sieve size Retained in

gm

Passing in

gm

Sample wt.

In gm

Percentage Req.

2.36 310 64 374 17.11 30%


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CHAPTER - 6

6. CONCRETE MIX DESIGN

A freshly mixed concrete for a period of two hours, from the time addition of water to

the dry ingredients is called the concrete mix. The problem of designing a mix for a given

purpose means obtaining a concrete of required strength, and workability at lowest cost, by

as suitable choice of materials and the proportions.

The following are the basic assumption made in design of concrete mix of medium

strength. The compressive strength of concrete is governed by its water-cement ratio (W/c

ratio).

For given aggregate characteristics, the workability of concrete is governed by its

water content.

There are following four widely used methods of mix design.

ACI mix design method

British mix design method.

USBR mix design

Mix design in accordance with the Indian standard recommended guide lines for

concrete mix design.

We have designed the mix as per the mix design in accordance with the Indian

standard recommended guide lines for concrete mix design.

a) Design Stipulations:

i. Characteristic Compressive Strength of cement : 43 N/mm2

ii. Maximum size of the aggregates : 20 mm


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b) Test data for Materials:

i. Specific Gravity of Cement : 3.15

ii. Specific Gravity of Coarse Aggregates(20mm) : 2.65

Specific Gravity of Coarse Aggregates(10mm) : 2.66

iii. Specific Gravity of Fine Aggregate : 2.70

iv. Concrete Designation : M50

v. Characteristic Compressive Strength (fck) : 50 N/mm2

vi. Water Absorption

a. Coarse Aggregates : 0%

b. Fine Aggregates : 0.7%

vii. Free (Surface) Moisture

a. Coarse Aggregates : 0%

b. Fine Aggregates : 1.0%

6.1 STEPS IN MIX DESIGN: (IS: 10262 - 2009)

A. Target Strength for Mix Proportioning:

f1ck=fck+1.65S

Where,

f1ck = Target average compressive strength at 28 days.

fck = Characteristic compressive strength at 28 days, and.

S = Standard deviation.

From Table 1, standard deviation, S= 5 N/mm2

Therefore, target strength = 50+1.65*5

=58.25 N/mm2

From Table 5 of IS 456, maximum water cement ratio = 0.35


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B. Selection of Water Content:

From Table 5 IS 10262-2009, maximum water content = 180 liter

As superplasticizer is used, the water content can be reduced up 20% and above.

Hence, the arrived water content =180*0.80=144 litre.

C. Calculation of Cement Content:

Water content ratio = 0.35

Cement content = 144/0.35

= 411.42kg/m3

Say 412 kg/m

3

From table 5 of IS 456 minimum cement content for severe exposure condition = 380kg/m3

412 kg/m3

> 380kg/m3

hence ok.

(Assuming 67% by volume of total aggregate)

Volume of course aggregate = 0.67*1.0=0.67

Volume of fine aggregate content =1-0.67=0.33

D. Mix Calculations:

a. Volume concrete=1m3

b. Volume cement content = mass of cement / specific gravity of cement * 1/ 1000

= 412/3.15*1/1000

= 0.1308m3

c. Volume of admixture = mass of admixture/specific gravity of adm*1/1000

= 4.994/10145*1/1000

= = 0.0043 m3

d. Volume water = mass of water / specific gravity of cement * 1/ 1000

= 144/1*1/1000

= 0.1440 m3


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e. Volume of all in aggregate = [a-(b + c)]

= 1-(0.1308+ 0.1440+0.0043)

= 0.7209 m

3

f. Mass of coarse aggregate = e * Volume of coarse aggregate * specific gravity of

coarse aggregate *1000

= 0.7209 *0.67*2.65*1000

= 1282.365kg/m3

Say 1284 kg/ m

3

g. Mass of fine aggregate = e * Volume of fine aggregate * specific gravity of fine

aggregate *1000

= 0.7209 *0.33*2.61*1000

= 620.919 kg/m3

Say 621 kg/m3

Taking coarse aggregate in two fractions of – 20mm: 10mm = 0.55:0.45

coarse aggregate 20mm = 706 kg/m3.

coarse aggregate 10mm = 578 kg/m3

Increasing cement, water, admixture by 2.5% for this trial

Cement = 412 X 1.025 = 422 kg

Water = 144 X 1.025 = 147.6 kg

Admixture = 1.2 % by weight of cement = 5.064 kg

FOR 1M3 MIX PROPORTION ARE

Cement = 422 kg/ m3

Admixture = 5.046 kg/ m3

Water = 147.6 kg/ m3

Fine aggregate = 621 kg/ m3

Coarse aggregate (20mm) = 706 kg/ m3

Coarse aggregate (10mm) = 578 kg/ m3

Water cement ratio = 0.35


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PROPORTION

Table.4

Cement Fine aggregate Coarse aggregate Water

412 621 1284 147.6

1.00 1.472 3.043 0.35


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CHAPTER - 7

7. CALCULATION OF REQUIRED QUANTITIES OF

CEMENT, FINE AND COARSE AGGREGATE CONTENT

FOR NOMINAL MIX (6 CUBES)

CEMENT = 422 x 0.15 x 0.15 x 0.15 x 6

= 8.5455 kg

FA = 1.472 x 8.5455

= 12.579 kg

CA = 3.043 x 8.5455

= 26 kg

WATER = 0.45 x 8.5455

= 3.845 liters

PLASTICIZER (BUILD PLAST)

For 50 kg of cement = 175 ml

For 8.5455 kg of cement = 29.9 ml


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FOR NOMINAL MIX (6 CYLINDERS)

CEMENT = 422 x 0.50 x 0.10 x 0.10 x 6

= 12.66 kg

FA = 1.472 x 12.66

= 18.63kg

CA = 3.043 x 12.66

= 38.52 kg

WATER = 0.45 x 12.66

= 5.7 liters





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FOR NOMINAL MIX (6 BEAMS)

CEMENT = 422 x 0.50 x 0.10 x 0.10 x 6

= 12.66 kg

FA = 1.472 x 12.66

= 18.63kg

CA = 3.043 x 12.66

= 38.52 kg

WATER = 0.45 x 12.66

= 5.7 liters





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7.1 TABULATION OF QUANTITIES OF MATERIALS

(PER 6 CUBES)

Table.5

MATERIALS OPC

CONCRETE

SLAG

CONCRETE

FLYASH

CONCRETE

TOTAL

QUANTITY

CEMENT(kg) 8.54 8.54 8.54 25.62

FINE AGG.(kg) 12.56 12.56 12.56 37.68

COARSE AGG.(kg) 26 26 26 78

WATER CONTENT(ltrs) 3.85 3.85 3.85 11.54

ADMIXTURE 30 30 30 90

(PER 6 CYLINDERS)

Table.5.1

MATERIALS OPC

CONCRETE

SLAG

CONCRETE

FLYASH

CONCRETE

TOTAL

QUANTITY

CEMENT(kg) 13.42 13.42 13.42 40.26

FINE AGG.(kg) 19.75 19.75 19.75 59.25

COARSE AGG.(kg) 45.66 45.66 45.66 136.98


ADMIXTURE 47 47 47 141

(PER 6 BEAMS)

Table.5.3

MATERIALS OPC

CONCRETE

SLAG

CONCRETE

FLYASH

CONCRETE

TOTAL

QUANTITY

CEMENT(kg) 12.66 12.66 12.66 38

FINE AGG.(kg) 18.63 18.63 18.63 56

COARSE AGG.(kg) 38.52 38.52 38.52 115.6


ADMIXTURE 43.92 43.92 43.92 131.76


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CHAPTER - 8

8. TEST PROCEDURE

8.1.1 CUBE MOULDS

Cube moulds are the standard square size blocks made of steel. They are open at top

and having a base plate at bottom. Steel cube moulds are made of 6mm thick and

(150*150*150) mm size.

8.1.1 A. Compressive Strength

Compressive strength is the primary physical property of concrete (others are

generally defined from it), and is the one most used in design. It is one of the fundamental

properties. Compressive strength may be defined as the measured maximum resistance of a

concrete specimen to axial loading. It is found by measuring the highest compression stress

that a test cube will support.

There are three type of test that can be use to determine compressive strength; cube,

cylinder, or prism test. The ‘concrete cube test' is the most familiar test and is used as the

standard method of measuring compressive strength for quality control purposes (Neville,

1994). Please refer appendix 1 for details.

Compressive strength = P/A N/mm2

Where,

P = Failure load in N.

A = Cross section area of the specimen in mm2


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8.1.1 B. Spilt Tensile Strength

This test is also called “Brazilian test” test is carried out by placing cylinder specimen

horizontal b/w the loading surfaces of compression testing machine and load is applied with

failure of cylinder along the vertical diameter the main advantages of this test is that the same

type of spaceman as are used for the compression test can employed for this test also.

Spilt tensile strength=(2p/πd2) N/mm

2

Where,

P = Failure load in N.

D=diameter of cylinder in mm.

8.1.1 C. Flexural Strength

The Flexural strength of concrete is determined by subjecting a plain concrete beam

to flexure under transfer loads. Concrete is relatively strong in compression and weak in

tension. In reinforced concrete the tensile stress are resisted by the provision of reinforced

steel. However tensile stressed are likely to develop in concrete due to drying, shrinkage,

rousting of steel reinforcement, temperature variations and many other reasons.

A concrete road slab as to resist tensile stress from to principle sources wheel loads

and volume changes in concrete. Wheel may cause high tensile stress due to bending when

there is in adequate sub grade support. Volume changes from change in temperature and

from the moisture may cause tensile stress due to warping and due to moment of slab along

the sub grade.

Beam moulds are standard rectangular size blocks made of steel. They are open at top having

a base plate at bottom. Steel cubes moulds are made up of 6mm thick and (100*100*500)

mm size.


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Machine: Universal testing machine (UTM) – 40 Tone capacities.

Flexural strength = δ =P*l/b*d2

N/mm2

Where,

P = failure load in Newton and

l =length of the specimen

b = width of the specimen in mm

d = depth of specimen in mm


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CHAPTER - 9

9. METHODOLOGY

9.1 CUBE TEST

Objective: To determine the compressive strength of a concrete sample.

Apparatus:

Standard cube size 150mm^3

Vibrating machine

General note:

Compressive strength will be determined at the age of 7 and 28 days.

3 samples for each age will be prepare. Average result will be taken.

Procedure:

Prepare the mould; apply lubricant oil in a thin layer to the inner surface of the

mould to prevent any bonding reaction between the mould and the sample

(A.M Neville, 1994).

Overfill each mould with sample in three layers (Standard Method: BS

1881:Part -3: 1970).

Fill 1/3 of the mould with sample. This would be the first layer.

Compact sample with vibrating machine. Compaction should be done

continuously.

Fill 2/3 of the mould; second layer. Repeat step 4.

Continue with the third layer and repeat the same compaction step.

After compaction has been completed, smooth off by drawing the flat side of

the trowel (with the leading edge slightly raised) once across the top of each

cube.

Cut the mortar off flush with the top of the mould by drawing the edge of the

trowel (held perpendicular to the mould) with a sawing motion over the

mould.

Tag the specimen, giving party number, and specimen identification.

Store cube in moist closet (temperature; 18˚C - 24˚C) for 24 hours.


SDMCET DHARWAD-02

Open mould and preserved cube in water (temperature; 19˚C - 21˚C) – BS

1881; Part 3: 1970.

Test cube for 7 days and 28 days accordingly.

Placed cube on the testing machine: cube position should be perpendicular

with its pouring position ( A.M. Neville, 1994).

Without using any capping material, apply an initial load ( at any convenient

rate) up to one-half of the expected maximum load (G.E. Troxell, 1956).

Loading should be increased at a uniform increment; 15 MPa/min (2200

Psi/min) – BS 1881: Part 4: 1970. Since that certain sample are expected to

have lower compressive strength, some adjustment will be made; loading will

be increased with the increment of 5% of the expected maximum

compressive strength.

When it comes nearer to the expected maximum strength, loading increment

will be lessen little by little ( A.M. Neville,1994).

9.2 CYLINDER TEST

Objective: To determine the split tensile strength of a concrete sample.

Apparatus:

Standard cylinder of 150mm diameter and 300mm height

Vibrating machine

General note:

Split tensile strength will be determined at the age of 7 and 28 days

.3 samples for each age will be prepare. Average result will be taken.

Procedure:




Overfill each mould with sample in three layers (Standard Method: BS

1881:Part -3: 1970).


SDMCET DHARWAD-02


Compact sample with vibrating machine. Compaction should be done

continuously.

Fill 2/3 of the mould; second layer. Repeat step 4.




cube.



mould.


Store cylinder in moist closet (temperature; 18˚C - 24˚C) for 24 hours.


1881; Part 3: 1970.

Test cylinder for 7 days and 28 days accordingly.

Placed cube on the testing machine: cylinder position should be horizontal

with its pouring position ( A.M. Neville, 1994).

Without using any capping material, apply an initial load ( at any convenient




have lower compressive strength, some adjustment will be made; loading will

be increased with the increment of 5% of the expected maximum

compressive strength.




SDMCET DHARWAD-02

9.3 BEAM TEST

Objective: To determine the flexural strength of a concrete sample.

Apparatus:

Standard beam size 100mm*100mm*500mm

Vibrating machine

General note:

Flexural strength will be determined at the age of 7 and 28 days.

3 samples for each age will be prepared. Average result will be taken.

Procedure:




Overfill each mould with sample in three layers (Standard Method: BS 1881:

Part -3: 1970).


Compact sample with vibrating machine.. Compaction should be done

continuously.

Fill 2/3 of the mould; second layer. Repeat above procedure.




beam.



mould.


Store beams in moist closet (temperature; 18˚C - 24˚C) for 24 hours.



SDMCET DHARWAD-02

1881; Part 3: 1970

Test beam for 7 days, 14 days and 28 days accordingly.

Placed beam on the UTM machine: cube position should be perpendicular

with its pouring position (A.M. Neville, 1994).

Without using any capping material, apply an initial load (at any convenient




have lower flexural strength, some adjustment will be made; loading will be

increased with the increment of 5% of the expected maximum flexural

strength.




SDMCET DHARWAD-02

CHAPTER - 10

10. CONDUCTING OF CONCRETE PREPARATION

(PICTURE GALLERY)


SDMCET DHARWAD-02

10.1 SLUMPS OBTAINED

Opc concrete = 110 mm to 120 mm

Fly ash concrete = 90 mm to 100 mm

Ggbs concrete = 70 mm to 80 mm


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10.2 COMPACTION FACTOR TEST

a) OPC CONCRETE

Weight of the empty cylinder (W1) = 6000 gm

Weight of the cylinder+uncompacted concrete (W2) = 18750 gm

Weight of the cylinder+compacted concrete (W3) = 18800 gm

CF = 0.9

b) GGBS CONCRETE



Weight of the cylinder+compacted concrete (W3) = 20455 gm

CF = 0.88


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c) FLYASH CONCRETE



Weight of the cylinder+compacted concrete (W3) = 20770gm

CF = 0.86


SDMCET DHARWAD-02

CHAPTER - 11

11.TEST RESULTS

11.1.1 Compressive strength results of opc concrete cubes are listed

below.

Size of the cubes: 150mm x 150mm x 150mm.

For 7 days

Table No.6

Sl.no C/s area

‘A’mm

Failure load

‘P’ N

Comp.

strength

P/A

N/mm2

Avg. comp.

strength

N/mm2

1 22500 810000 36.00

35.92

Say 36.00 2 22500 815000 36.22

3 22500 800000 35.55

For 28 days

Table No.6.1

Sl.no C/s area

‘A’mm

Failure load

‘P’ N

Comp.

strength

P/A

N/mm2

Avg. comp.

strength

N/mm2

1 22500 1200000 53..33

52.22

2 22500 1105000 49.11

3 22500 1220000 54.22


SDMCET DHARWAD-02

11.1.2 Compressive strength results of GGBS concrete cubes are listed

below.


For 7 days

Table No.7

Sl.no C/s area

‘A’mm

Failure load

‘P’ N

Comp.

strength

P/A

N/mm2

Avg. comp.

strength

N/mm2

1 22500 860000 38.22

37.70

Say 38.00 2 22500 845000 37.55

3 22500 840000 37.33

For 28 days

Table No.7.1

Sl.no C/s area

‘A’mm

Failure load

‘P’ N

Comp.

strength

P/A

N/mm2

Avg. comp.

strength

N/mm2

1 22500 1395000 62.50

59.33

2 22500 1300000 57.77

3 22500 1310000 58.22


SDMCET DHARWAD-02

11.1.3 Compressive strength results of fly ash concrete cubes are listed

below.


For 7 days

Table No.8

Sl.no C/s area

‘A’mm

Failure load

‘P’ N

Comp.

strength

P/A

N/mm2

Avg. comp.

strength

N/mm2

1 22500 890000 39.55

39.92

Say 40.00 2 22500 910000 40.44

3 22500 895000 39.77

For 28 days

Table No.8.1

Sl.no C/s area

‘A’mm

Failure load

‘P’ N

Comp.

strength

P/A

N/mm2

Avg. comp.

strength

N/mm2

1 22500 1460000 65

64.66

2 22500 1460000 65

3 22500 1440000 64


SDMCET DHARWAD-02

11.2.1 Split tensile strength of OPC concrete cylinder

Size of the cylinder : 150mm diameter and 300mm height

For 28 days

Table No.9

Sr no C/s area,

‘A’ = 2

mm2

Failure load

‘P’ N

Tensile

strength

= 2p/ DL

N/mm2

Average

Tensile

strength

N/mm2

1. 17671.45 300000 4.24

4.28 2. 17671.45 300000 4.24

3. 17671.45 310000 4.38

11.2.2 Split tensile strength of GGBS concrete cylinder

For 28 days

Table No.9.1

Sr no C/s area,

‘A’ = 2

mm2

Failure load

‘P’ N

Tensile

strength

= 2p/ DL

N/mm2

Average

Tensile

strength

N/mm2

1. 17671.45 360000 5.09

5.04 2. 17671.45 350000 4.95

3. 17671.45 360000 5.09


SDMCET DHARWAD-02

11.2.3 Split tensile strength of Fly ash concrete cylinder

For 28 days

Table No. 9.2

Sr no C/s area,

‘A’ = 2

mm2

Failure load

‘P’ N

Tensile

strength

= 2p/ DL

N/mm2

Average

Tensile

strength

N/mm2

1. 17671.45 339823 4.81

4.93 2. 17671.45 350424 4.96

3. 17671.45 354663 5.02


SDMCET DHARWAD-02

11.3 Flexural strength of opc, fly ash and ggbs concrete beam

are listed below:

Size of the beams: 100mm x 100mm x 500mm.

The following table gives the Flexural strength test results.

For 7 days

Table No. 10

Sr no C/s area,

‘A’ =

mm2

Failure load

‘P’ N

Flexural

strength

= Pl/b 2

N/mm2

1.opc 10000 4905 2.45

2.fly ash 10000 6376.5 3.18

3.ggbs 10000 5346 2.67


SDMCET DHARWAD-02

11.4 COMPARISON BETWEEN DIFFERENT TYPES OF M50

GRADE CONCRETES

Table No. 11

Properties OPC concrete GGBS concrete FLYASH concrete

Slump(mm) 110 - 120 70 -80 90-100

Compaction Factor 0.9 0.88 0.86

Compressive

strength at 28

days(N/mm2)

52.22 59.33 64.66

Split tensile

strength at 28

days(N/mm2)

4.28 5.04 4.93

Flexural strength at

7 days(N/mm2)

2.45 2.67 3.18


SDMCET DHARWAD-02

CHAPTER – 12

CONCLUSION

From the project we can conclude that use of cements made from industrial waste

materials viz fly ash and GGBS to a certain extent increases the overall performance

of the particularly designed M50 grade concrete.

From the test results obtained we can say that the compressive strength of FLY ASH

concrete is much higher than the target mean strength.

It is observed that compressive strength of fly ash concrete at 28 days is meeting

target mean strength, and will increase upto 90 days(more than 10N/mm 2

-

20N/mm2).

From the slump values obtained the OPC concrete is free flowing but does not match

with the target mean strength, Where as fly ash and GGBS concrete are having less

free flow but matches the target mean strength.


SDMCET DHARWAD-02

CHAPTER - 13

SCOPE

For the works demanding high performance of concrete in respect of strength and

workability, The designed M50 concrete using GGBS and fly ash cements can be

used.

We can still improve the strength of these concretes by adding certain amount of

crusher powder.

Early age heat of hydration of concrete can be reduced using GGBS concrete which

will reduce water usage for curing.

workability tests can be carried out like funnel test, U tube tests etc.


SDMCET DHARWAD-02

CHAPTER - 14

REFERENCES

[1] A.M.Neville, “Properties of concrete”, Pearson education Asia pte ltd, England.

[2] M.S. Shetty, “Concrete Technology”, 5th

edition, S.Chand publications.

[3] Proceedings of seventh international conference on Fly Ash, Silica Fume, Slag and

Natural Pozzolans in Concrete-Vol-II Editor- V.M.Malhotra.

[4] THE INDIAN CONCRETE JOURNAL (VOL.85 – NO.03 - MARCH 2011)- Published

by ACC Limited.

[5] The Indian concrete journal, September 2002.

[6] “ASIAN JOURNAL OF CIVIL ENGINEERING (BUILDING AND HOUSING) “VOL.

10, NO.3 (2009) – V. Bhishma Kalidas Nitturkar and Y. Venkatesham.

[7] IS CODE 456-2000,10262-2009,383-1970,1199-1959.

[8] www.civilcampus.net ,Wikipedia.

[9] Bagalkot cement factory, Bagalkot.

High Performance Concrete

Engineering

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