STUDIES ON REACTIVE POWDER CONCRETE.docx

8/10/2019 STUDIES ON REACTIVE POWDER CONCRETE.docx

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STUDIES ON REACTIVE POWDER CONCRETE-ULTRA

HIGH STRENGTH CONCRETE

SEMINAR REPORT

Submi tted by

N. SIVA RAM KRISHNA

ROLL NO: 141519

in the partial ful fi llment of the requirements for

The award of the degree of

MASTER OF TECHNOLOGY

INENGINEERING STRUCTURES

Under The Guidance of

Dr.D.Ravi Prasad

Assistant Professor in Civil Engineering Department

NATIONAL INSTITUTE OF TECHNOLOGY

WARANGAL-506004


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NATIONAL INSTITUTE OF TECHNOLOGY

WARANGAL-506004

CERTIFICATE

This is certified thatN. SIVA RAMA KRISHNAhas submitted the seminar report on

STUDIES ON REACTIVE POWDER CONCRETE- ULTRA HIGH STRENGTH

CONCRETEin partial fulfillment of the 1stsemester M.Tech course in Engineering

Structures as prescribed by the National Institute of Technology, Warangal during

academic year 2014-2015 under the guidance of Dr .D.Ravi Prasad.

Dr.D.Ravi Prasad

Assistant Professor

Department of Civil Engineering


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ACKNOWLEDGEMENTS

I express my deep sense of gratitude to Dr.D.Ravi Prasad sir, Assistant Professor in

Department of Civil Engineering, National Institute of Technology, Warangal for his invaluable

guidance, motivation and constant encouragement throughout the course of this seminar work.

I will remain thankful to all the faculty members of Department of Civil Engineering,

NIT Warangal for their support during the course of this work.

Finally, we express gratitude to our parents for supporting us in every walk of life.

N. Siva Rama Krishna

M.Tech (Engineering Structures)

National Institute of Technology, Warangal


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ABSTRACT

Concrete is a versatile and critical material for the construction of infrastructure facilities throughout

the world. A new developing material known as reactive powder (RPC) is available that differs

significantly from traditional concretes. It is catching more attention nowadays because of its high

mechanical and durability characteristics. RPC mainly comprise of cement, silica fume, silica sand,

quartz powder and steel fibers. RPC has been able to produce with compressive strength ranging from

200 MPa to 800 MPa with flexural strength up to 50 MPa. There is no coarse aggregate is present in

RPC. Since coarse aggregate is the weak link the concrete. The production of very high strength normal

weight Reactive powder concrete (RPC) requires detailed investigation of number of factors that have

and what can be done to optimized their contribution to the attainment of very high compressive

strength. In the present seminar I will focus to study the effects of w/c ratio, amount of silica fume,

curing conditions and the effect of mineral, chemical admixtures to achieve compressive strength.


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CONTENTS

1. INTRODUCTION

2. LITERATURE REVIEW

3. COMPOSITION OF REACTIVE POWDER CONCRETE

4. BENEFITS AND LIMITATIONS OF RPC

5. EXPERIMENTAL PROCEDURE

6.

RESULTS & DISCUSSIONS

7. CONCLUSIONS

8. REFERENCES


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INTRODUCTION

RPC is ultra-high-strength and high ductility cementations composite with advanced mechanical and

physical properties. It is a special concrete where the microstructure is optimized by precise gradation

of all particles in the mix to yield maximum density. It doesnt contain coarse aggregate, but contains

cement, silica fume, sand, quartz powder and steel fiber with very low water binder ratio. The absence

of coarse aggregate was considered by inventors to be key aspect for the microstructure and

performance of RPC in order to reduce the heterogeneity between cement matrix and aggregate.

RPC with trade name DUCTAL was developed in France by researchers Mr.

Richard and Mr. Cheyrezy in the early 1990s at Bouygues, laboratory in France. The worlds first RPC

structure, the Sherbrooke Bridge in Canada, was constructed in July 1997. RPC has been able to

produce with compressive strength ranging from 200 MPa to 800 MPa with flexural strength up to 50

MPa. Although suitable guidelines are not available to produce RPC in India, the present study focuses

on developing RPC of compressive strength up to 150 MPa. Without using steel fibers we can produce

strength up to 200 MPa.

This new material demonstrates greatly improved strength and durability

characteristics compared with traditional or even high-performance concrete. Classified as Ultra-High

Performance Concrete (UHPC), or Reactive Powder Concrete (RPC). The improved properties of RPC

are obtained by improving the homogeneity of the concrete by eliminating large aggregates, increasing

compactness of the mixtures by optimizing packing density of fine particles, and using fine steel fibersto provide ductility.

RPC will be suitable for pre-stressed application and for structures acquiring light and

thin components such as roofs of stadiums, long span bridges, space structures, high pressure pipes, and

blast resistance structures and the isolation and containment of nuclear wastes.


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LITERATURE REVIEW

Many researchers have carried out studies on RPC in the past years to assess the properties and its

behavior. Some of the works carried out re discussed below:

Richard and Cheyrezy (1995) developed an ultra-high strength ductile concrete with the basic

principles of enhancing the homogeneity by eliminating the coarse aggregate and enhancing the

microstructure by post-set heat treatment. In addition, the ductility and tensile strength of concrete is

increased by incorporating small, straight, high tensile micro fibers. Two types of concretes are

developed and designated as RPC 200 and RPC 800. These concretes had exceptional mechanical

properties, which resulted in elimination of reinforcement, and reduction of materials resulting in

reduction of self-weight resulting in cost savings. The concrete finds its applications in industrial and

nuclear waste storage silos.

Chan and Chu, [2002] has studied the effect of silica fume on the bond characteristics of steel fiber in

matrix of reactive powder concrete (RPC) by bond strength, pullout energy, etc. Various silica fume

contents ranging from 0% to 40% are used in the mix proportions. Results of them show that the

incorporation of silica fume can effectively enhance the fibermatrix interfacial properties, especially in

fiber pullout energy.

Dili and Manu Santhanam (2005) developed two RPC mixes of 200MPa and 800MPa strength,

which could be suitable for nuclear waste containment structures. The workability and durabilityproperties were studied for the designed RPC mix. Also characterization of mechanical properties was

carried out. The durability test carried out for the RPC mixes showed that the flow table test was in the

range of 120%-140% and the water and chloride ion Permeability is extremely low. These test results

indicates the suitability of the designed RPC mix for nuclear waste containment structures.

S. Lavanya Prabha [2010] conducted a study on complete stress-strain curves from uniaxial

compression tests. The effect of material composition on the stress strain behavior and the toughness

index were studied. The highest cylinder compressive strength of 171.3 MPa and elastic modulus of

44.8 GPa were recorded for 2% 13 mm length fibers. The optimum fiber content was found to be 3% of

6mm length or 2% of 13mm length fibres. A new measure of compression toughness known as MTI

(modified toughness index) was proposed by them and it is found to range from 2.64 to 4.65 for RPC

mixes.


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COMPOSITION OF REACTIVE POWDER CONCRETE

RPC is composed of very fine powders (cement, sand, quartz powder, steel aggregates and silica fume),

steel fibres (optimal) and a super plasticizer. The super plasticizers, used at its optimal dosage, decrease

the water to cement ratio (w/c) while improving the workability of the concrete. A very dense matrix is

achieved by optimizing the granular packing of the dry fine powders. This compactness gives RPC,

ultra-high strength and durability. Reactive powder concretes have compressive strengths ranging from

200 MPa to 800 MPa.

Mr. Richard and Mr. Cheyrezy indicate the following principles for developing RPC.

1. Enhancement of homogeneity by elimination of coarser aggregates.

2. Enhancement of compacted density by optimization of the granular mixture.

3. Enhancement of the microstructure by Post-set heat-treatment

4. Enhancement of ductility by addition of small-sized steel fibres

5. Application of pressure before and during setting to improve compaction

6. Utilization of the pozzolonic properties of silica fume.

7. The optimal usage of super plasticizer to reduce w/c and improve workability.

Table 1 lists salient properties of RPC, along with suggestions on how to achieve them. Table 2

describes the different ingredients of RPC and their selection parameters. The tables are obtained from

literature. The mixture design of RPC primarily involves the creation of a dense granular skeleton.Optimization of the granular mixture can be achieved either by the use of packing modelsor by particle

size distribution software, such as LISA[developed by Elkem ASA Materials].

Table: 1 Properties of RPC enhancing its homogeneity and strength

Property of

RPC

Description Recommended Values Types of failure

eliminated

Reduction in

aggregate size

Coarse aggregates are

replaced by fine sand,

with a reduction in the

size of the coarsest

aggregate by a factor of

about 50.

Maximum size of fine

sand is 600 m

Mechanical,

Chemical &

Thermo-mechanical


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Enhanced mechanical

properties

Improved mechanical

properties of the paste

by the addition of silica

fume

Youngs modulus

values in 50 GPa75

GPa range

Disturbance of the

mechanical stress field.

Reduction in aggregate

to matrix ratio

Limitation of sand

content

Volume of the paste is

at least 20% greater

than the voids index of

non-compacted sand.

By any external source

(e.g., formwork).

Table 2: Selection Parameters for RPC components

Components Selection

parameters

Function Particle Size Types

Sand Readily available

and low cost.

Good hardness

Give strength,

Aggregate

150 m

to

600 m

Natural,

Crushed

Cement C3S: 60%;

C2S : 22%;C3A : 3.8%;

C4AF: 7.4%.

(optimum)

Binding material,

Production ofprimary hydrates

1 mto

100 m

OPC,Medium

fineness

Quartz Powder

fineness

Max. reactivity

during heat-

treating

5 m

to

25 m

Crystalline

Silica fume Very less quantity

of impurities

Filling the voids,

Enhance

rheology,

Production of

secondary

hydrates

0.1 m

to

1 m

Procured from

ferrosilicon

industry


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Steel fibers Good aspect ratio Improve ductility L : 1325 mm

: 0.150.2 mm

Straight

Super Plasticizer Less retarding

characteristic

Reduced W/C - Polyacrylate

based

BENEFITS AND LIMITATIONS OF RPC

Benefits of RPC:

i. RPC is a better alternative to High Performance Concrete and has the potential to structurally

compete with steel.

ii. Its superior strength combined with higher shear capacity results insignificant dead load

reduction and limitless structural member shape.

iii. With its ductile tension failure mechanism, RPC can be used to resist all but direct primary

tensile stresses. This eliminates the need for supplemental shear and other auxiliary reinforcing

steel.

iv. RPC provides improve seismic performance by reducing inertia loads with lighter members,

allowing larger deflections with reduced cross sections, and providing higher energy absorption.

v. Its low and non-interconnected porosity diminishes mass transfer making penetration of

liquid/gas or radioactive elements nearly non-existent.

Limitations of RPC:

In a typical RPC mixture design, the least costly components of conventional concrete are basically

eliminated or replaced by more expensive elements. The fine sand used in RPC becomes equivalent to

the coarse aggregate of conventional concrete, the Portland cement plays the role of the fine aggregate

and the silica fume that of the cement. The mineral component optimization alone results in a

substantial increase in cost over and above that of conventional concrete (5 to 10 times higher thanHPC). RPC should be used in areas where substantial weight savings can be realized and where some

of the remarkable characteristics of the material can be fully utilized.

Since RPC is in its developing stage, the long-term properties are not known.


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EXPERIMENTAL PROCEDURE

The present study focuses on developing RPC of compressive strength up to 150 MPa. Along with the

development of RPC, various factors affecting the strength of RPC are studied. The 100100100 mm

size RPC cube specimens were cast by varying the constituent materials and cured at both normal and

high temperature before testing for their strength.

Materials Used in Mix design:

Cement:The Ultra-Tech 53 Grade Ordinary Portland cement (OPC) which complies with IS: 12269-

1987 is used in the present study. Its specific gravity is 3.15

The Silica fume: 945 D from Elkem India Ltd. which complies with ASTM C 1240

95a and IS: 15388-2003 is used in the study. It contains sio2 90%. Maximum size of the particle is

15m. Its specific gravity is 2.2

Quartz Powder- The crushed quartz with particle size ranging from 10m to 45m is used. The

specific gravity of quartz powder is 2.6

Silica Sand: It is yellowish-white high purity silica sand. The particle size of sand is 150m 600m.

Super Plasticizer: The very low w/b ratio required for RPC can be achieved with use of super

plasticizer (SP) to obtain good workability. In this study, the 2nd generation of super plasticizer called

Glenium B-276 Surtec from BASF India Ltd. was used.

To study the influence of the constituent materials, 14 different proportions were

considered by varying water-binder ratio, silica fume and quartz powder content. Cement of quantity

900 kg/m3 was kept constant for all the mixes. The water-binder ratio of the mixes varied from 0.16 to

0.24. Silica fume was added by 15 to 25 percent by weight of cement. 20 percent of quartz powder by

weight of cement was also added for few mixes. Super plasticizer dosage varied from 1 to 4 percent for

all the mixes. Detailed mix proportioning is mentioned in Table 3 from literature.


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Table 3: Proportioning of RPC mixes

MIX TM1 TM2 TM3 TM4 TM5 TM6 TM7 TM8 TM9 TM10 TM11 TM12 TM13 TM14

MATERIAL 15% silica fume 20% silica fume 25% silica fume 15% Silica fume +

20%Quartz Powder

Cement 1 1 1 1 1 1 1 1 1 1 1 1 1 1

Silica

Fume

0.15 0.15 0.15 0.15 0.15 0.20 0.20 0.20 0.25 0.25 0.25 0.15 0.15 0.15

Quartz

Powder

- - - - - - - - - - - 0.2 0.2 0.2

Sand 1.33 1.28 1.24 1.19 1.15 1.16 1.11 0.91 0.98 0.98 0.92 0.82 0.82 0.82

W/B

ratio

0.16 0.18 0.20 0.22 0.24 020 0.22 0.24 0.20 0.22 0.24 0.18 0.2 0.22

SP % 3 2.5 2 1.5 1 3 2.5 2 4 3 2 3 2.5 2

Curing

Regime

Water curing at room temperature and steam curing at 90 0c for 48 hours.

For each batch of concrete, 100 x 100 x 100 mm cubes were cast to evaluate compressive strength

(IS: 10086-1999). The specimens were cured at both normal temperature for 28 days and at 90 C for

48 hours, remaining 26 days at normal temperature. The casted specimens were tested for 7days and 28

days compressive strength.


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RESULTS AND DISCUSSIONS

Arriving at optimal composition with locally available materials is important to achieve the best overall

performance of RPC. Hence, the effects of several parameters on compressive strength were

investigated which include water-to-binder ratio, super plasticizer dosage, different percentage of silica

fume, with and without quartz powder and curing regime. During the study it was observed that the

mixes appeared to be very sensitive to any variation of the chemical composition of the binders or

particle size distribution of the fillers. As there are no standard guidelines for the mix design of RPC,

literature was referred to design the mixes. The silica fume content was varied from 15 to 25 percent by

weight of cement to find the optimum percentage of silica fume in the production of RPC. To study the

influence of addition of quartz powder to RPC, the RPC mixes were also designed with addition of

quartz powder by 20 percent by weight of cement.

Effect of water to binder ratio on compressive strength: The strength of concrete depends upon the

hydration process in which waterplays critical role. The effect of W/b ratio on compressive strength is

shown in fig. 1 at different curing days. From the results we came to know that optimum w/b 0.2 which

gives more compressive strength. The reduction strength at lower w/b ratio is due to insufficient

amount of water for complete hydration process to occur.


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Beyond 0.2 strength is decreasing due to excess amount of water which will create entrainment of air

bubbles.The compressive strengths of all mix proportions at 7 and 28 days are tabulated in Table 4

Table 4: Compressive strength of RPC

Sample No

Normal Curing at 27 C Accelerated Curing at 900C for 48

hours

Compressivestrength at 7 days

N/mm2

Compressivestrength at 28

days

N/mm2

Compressivestrength at 7 days

N/mm2

Compressivestrength at 28

days

N/mm2

TM-1 72 116 81 124

TM-2 70 120 85 132

TM-3 94 128 99 138

TM-4 69 110 78 121

TM-5 66 112 76 119

TM-6 62 93 - -

TM-7 58 95 - -

TM-8 56 87 - -

TM-9 61 96 - -

TM-10 55 90 - -

TM-11 57 85 - -

TM-12 88 112 94 138

TM-13 91 117 105 146

TM-14 85 109 89 122


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Effect of Addition of quartz powder:

Quartz powder improves the filler effect in RPC mix. Quartz powder produce the better result under

accelerated curing condition than that of normal curing condition which is shown in Fig 3. The results

show that the addition of quartz powder increases the compressive strength by 20% under the

accelerated curing condition.

Fig 3: The effect of Quartz powder on compressive strength of RPC


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Influence of Curing Regime:

An adequate supply of moisture is necessary to ensure that hydration is sufficient to reduce the porosity

to a level such that the desired strength can be attained. The effect of curing regime on compressive

strength under various curing ages is shown in Fig. 4. Two curing methods were exercised, one with

normal water curing at 27C, and other at 90C hot water curing for 48 hours. The compressive strength

increased by 10% when cured in hot water as compared to normal curing. This indicates that curing

temperature has a significant effect on the early strength development of RPC. The increased strength is

due to the rapid hydration of cement at higher curing temperatures of 90C compared to that of 27C.

Moreover, the pozzolonic reactions are also accelerated by the higher curing temperatures.

Fig 4: Effect of curing regime on Compressive strength of RPC


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CONCLUSIONS

Following are the conclusions that can be drawn from laboratory results:

a. The maximum compressive strength of RPC obtained in the present study is 146 MPa at

W/b ratio of 0.2 with accelerated curing.

b. In the production of RPC the optimum percentage addition of silica fume is found to be

15% (by weight of cement) with available super plasticizer.

c. The addition of quartz powder increases the compressive strength of RPC up to 20%

d. The high temperature curing is essential for RPC to achieve higher strength. It increases

the compressive strength up to 10% when compared with normal curing.

Reactive Powder Concrete (RPC) is an emerging technology that lends a new

dimension to the term high performance concrete. It has immense potential in construction due to its

superior mechanical and durability properties compared to conventional high performance concrete,

and could even replace steel in some applications.The development of RPC is based on the application

of some basic principles to achieve enhanced homogeneity, very good workability, high compaction,

improved microstructure, and high ductility. RPC has an ultra-dense microstructure, giving

advantageous waterproofing and durability characteristics. It could, therefore, be a suitable choice for

industrial and nuclear waste storage facilities. Its application in India is very little or nil due to there is

no experimental guidelines. Currently research is going on this RPC at CSIR-SERC, Chennai.


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REFERENCES

1. Richard P., Cheyrezy M., Composition of Reactive Powder Concretes, Cement and

Concrete Research, Vol. 25, No. 7, pp. 1501-1511, 1995.

2. Cheyrezy M. et al., Microstructural Analysis of RPC, Cement and Concrete Research,

Vol. 25, No. 7, pp. 1491-1500, 1995.

3. S. Lavanya Prabha., J.K.Dattatreya., Study on stress-strain properties of reactive powder

concrete under uniaxial compression, International Journal of Engineering Science and

Technology Vol. 2(11), 2010, 6408-6416.

4. MK.Maroliya., An Investigation on Reactive Powder Concrete containing Steel Fibers and Fly-

Ash, International Journal of Emerging Technology and Advanced Engineering, Volume 2,

Issue 9, September 2012.

5.

Khadiranaikar R.B. and Muranal S. M., Factors affecting the strength of Reactive Powder

Concrete, International Journal of Civil Engineering and Technology,Volume 3, Issue 2, July-

December (2012), pp. 455-464.

6. Mr.Anjan kumar M U, Dr. Asha Udaya Rao, Dr. Narayana Sabhahit,Reactive Powder Concrete

Properties with Cement Replacement Using Waste Material,International Journal of Scientific

& Engineering Research Volume 4, Issue 5, May-2013.

7. http://www.theconcreteportal.com/

8. http://rebar.ecn.purdue.edu/ect/links/technologies/civil/reactive.aspx
http://www.theconcreteportal.com/http://www.theconcreteportal.com/http://rebar.ecn.purdue.edu/ect/links/technologies/civil/reactive.aspxhttp://rebar.ecn.purdue.edu/ect/links/technologies/civil/reactive.aspxhttp://rebar.ecn.purdue.edu/ect/links/technologies/civil/reactive.aspxhttp://www.theconcreteportal.com/

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