1

REPLACEMENT OF CEMENT WITH RICE HUSK ASH (RHA)

A Project Report

Submitted in partial fulfillment of the Requirements for the award of the degree

Of

Bachelor of Technology

In

CIVIL ENGINEERING

BY

Praveer Bhriguvanshi (110107140)

Anshuman Mani (110107038)

Amitesh Kumar (110107032)

Pal Shweta Prakash (110107127)

DEPARTMENT OF CIVIL ENGINEERING

SHARDA UNIVERSITY, GREATER NOIDA

Uttar Pradesh-201306 (INDIA)

APRIL, 2015

2

CERTIFICATE

We hereby certify that the work which is being presented in the B.Tech. Major Project Report

entitled “REPLACEMENT OF CEMENT WITH RICE HUSK ASH”, in partial

fulfillment of the requirements for the award of the Bachelor of Technology in Civil

Engineering and submitted to the Department of Civil Engineering of Sharda University,

Greater Noida is an authentic record of our own work carried out during a period from January

2015 to May 2015 under the supervision of MR. PRASHANT KUMAR (ASSISTANT

PROFESSOR), Civil Department.

The matter presented in this thesis has not been submitted by me for the award of any other

degree elsewhere.

Signature of Candidate

Praveer Bhriguvanshi (110107140)

Anshuman Mani (110107038)

Amitesh Kumar (110107032)

Pal Shweta Prakash (110107127)

This is to certify that the above statement made by the candidate is correct to the best of my

knowledge.

Signature of Supervisor(s)

Date: 24-04-2015 PRASHANT KUMAR ASSISTANT PROFESSOR

Head of Department CIVIL Engineering Department Sharda University, Greater Noida

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ACKNOWLEDGEMENT

We place on record and warmly acknowledge the continuous encouragement,

In valuable supervision, timely suggestions and inspired guidance offered by our

Guide Mr. PRASHANT KUMAR, Assistant Professor in bringing this report to

a successful completion for permitting us to make use of the facilities available in

the department to carry out the project successfully.

Our sincere Thanks to all the lab attendant who helps us in doing our project. Last

but not the least we express our sincere thanks to all our friends who have patiently

extended all kind of help for accomplishing this undertaking. Finally we extend our

gratitude to one and all who are directly or indirectly involved in the successful

completion of this project work.

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ABSTRACT

The optimized RHA, by controlled burn or grinding, has been used as a pozzolanic material in

cement and concrete. Using it provides several advantages, such as improved strength and

durability properties, and environmental benefits related to the disposal of waste materials and to

reduced carbon dioxide emissions. Up to now, little research has been done to investigate the use

of RHA as supplementary material in cement and concrete production .The main objective of

this work is to study the suitability of the rice husk ash as a pozzolanic material for cement

replacement in concrete. However it is expected that the use of rice husk ash in concrete improve

the strength properties of concrete. Also it is an attempt made to develop the concrete using rice

husk ash as a source material for partial replacement of cement, which satisfies the structural

properties of concrete like compressive strength.

From the entire experimental work & studies it is concluded that mix M20 with the replacement

of 20% is the best combination among all mixes, which gives the maximum compressive

strength.

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List of Figures

Sr.No FIGURE NO NAME OF FIGURE PAGE NO

1. FIG-1 Rice Husk Ash 12

2. FIG-2 Flow chart depicting the methodology 22

3. FIG-3 Slump test being performed 31

4. FIG-4 Before demoulding of slump mould 31

5. FIG-5 Slump height being checked after removal of mould 32

6. FIG-6 Moulds of size 150*150 33

7. FIG-7 Casting of concrete cubes 33

8. FIG-8 Tampering of concrete being done 34

9. FIG-9 Tampering of concrete being done 34

10. FIG-10 Compressive test machine 37

11. FIG-11 Compressive test being done at 28 days 38

12 FIG-12 Graph shows variation in compressive strength 39

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List of Tables

SR.NO TABLE NO NAME OF TABLE PAGE NO

1. Table 1 Physical properties of RHA 13

2. Table 2 Chemical properties of RHA 13

3. Table 3 Sieve analysis of sand 24

4. Table 4 Sieve analysis of gravel (20mm) 24

5. Table 5a. Amount of ingredients Without replacement of

RHA for casting

29

6. Table 5b With 20% replacement of RHA 29

7. Table 6 Compressive strength at different curing days 39

7

List of Abbreviations

1. R.H.A…………..……….……RICE HUSK ASH

2. C.A…………………………...COARSE AGGREGATE

3. F.A……………………………FINE AGGREGATE

4. S.G……………………………SPECIFIC GRAVITY

5. W/C…………………………..WATER CEMENT RATIO

6. O.P.C………………………...ORDINARY PORTLAND CEMENT

7. I.S…………………………….INDIAN STANDARED

8. N/mm2....................................NEWTON PER MILI METER SQUARE

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CONTENTS

CHAPTER NO NAME OF TOPIC PAGE NO

1 Introduction 11-18

1.1 What is RHA 11

1.2 Properties of RHA 11

1.3 Material used 13

A Rice Husk ash 13

B Cement 13

B (i) Chief chemical component of opc 14

B (ii) Basic composition 14

B (iii) Characteristics of opc 43 grade 15

B (iv) Setting and hardening 15

B (v) Use of opc 43 grade 15

C Concrete 16

C (i) History 16

C (ii) Characteristics of good concrete 16

D Aggregates 16

D (i) Classification of aggregates 17

1.4 Objectives 17

1.5 Scope of project 18

2 Literatures of Review 19-20

3 Methodology 21-22

3.1 General 21

3.2 Flow chart 22

4 Test to be performed 23-24 4.1 Sieve analysis 23

5 Mix design 25-29

9

CHAPTER NO NAME OF TOPIC PAGE NO

6 Experimental work 30-38 6.1 Preparation of material 30

6.2 Slump test 30-32

6.3 Casting 33-35

6.4 Curing 35

6.5 Compressive test 36-38

7 Results and Graphs 39 7.1 Compressive strength test 39

8 Pros and Cons 40-42 8.1 Advantage of rice husk ash 40

8.2 Disadvantage of rice husk ash 41

8.3 Conclusion 42

9 Reference 43

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CHAPTER-1

Introduction

1.1 what is R.HA Rice husk can be burnt into ash that fulfills the physical characteristics and chemical composition

of mineral admixtures. Pozzolanic activity of rice husk ash (RHA) depends on (i) silica content,

(ii) silica crystallization phase, and (iii) size and surface area of ash particles. In addition, ash

must contain only a small amount of carbon.The optimized RHA, by controlled burn and/or

grinding, has been used as a pozzolanic material in cement and concrete. Using it provides

several advantages, such as improved strength and durability properties, and environmental

benefits related to the disposal of waste materials and to reduced carbon dioxide emissions.

RHA produced after burning of Rice husks (RH) has high reactivity and pozzolanic property.

Chemical compositions of RHA are affected due to burning process and temperature. Silica

content in the ash increases with higher the burning temperature.The effect of partial replacement

of cement with different percentages of ground RHA on the compressive strength and durability

of concrete is examined.

1.2 Properties of RHA Rice Husk Ash is a Pozzolanic material. It is having different physical & chemical properties.

The product obtained from R.H.A. is identified by trade name Silpoz which is much finer than

cement.

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Fig 1 : Rice husk ash (R.H.A) (Ref. thailand.ipm-info.org)

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Table 1: Physical Properties of R.H.A

Table 2: Chemical properties of R.H.A

1.3 MATERIALS USED

(A) Rice Husk Ash (RHA). Rice Husk Ash was burnt for approximately 72hours in air in an uncontrolled burning

process. The temperature was in the range of 400-600 degree C .The ash collected was sieved

through BS standard sieve size 75µm and its colour was grey.

(B) Cement Ordinary Portland cement (OPC) of 43 grade was used in which the composition and

properties is in compliance with the Indian standard organization.

Cement can be defined as the bonding material having cohesive & adhesive properties which

makes it capable to unite the different construction materials and form the compacted assembly.

Ordinary/Normal Portland cement is one of the most widely used type of Portland Cement. The

name Portland cement was given by Joseph Aspdin in 1824 due to its similarity in color and its

S.No PARTICULARS PROPERTIES

1 Colour Gray

2 Shape texture Irregular

3 Mineralogy Non crystalline 4 Particle size >45 micron

5 Odour Odourless

6 Specific gravity 2.3

S.No Particulars Proportion

1 Silicon dioxide 86.94%

2 Aluminum oxide 0.2%

3 Iron oxide 0.1%

4 Calcium Oxide 03.-2.2%

5 Magnesium Oxide 0.2- 0.6%

6 Sodium Oxide 0.1- 0.8%

7 Potassium Oxide 2.15-2.30%

8 Ignition Loss 3.15-4.4%

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quality when it hardens like Portland stone. Portland stone is white grey limestone in island of

Portland, Dorset.

B (i) The chief chemical components of ordinary Portland cement are:

1. Calcium

2. Silica

3. Alumina

4. Iron

Calcium is usually derived from limestone, marl or chalk while silica, alumina and iron come

from the sands, clays & iron ores. Other raw materials may include shale, shells and industrial

by products.

B (ii) BASIC COMPOSITION

Contents %

i. CaO 60-67

ii. SiO2 17-25

iii. Al2O 3 3-8

iv. Fe2O 3 0.5-6.0

v. MgO 0.5-4.0

vi. Alkalis 0.3-1.2

vii. SO 3 2.0-3.5

The chief compound which usually form in process of mixing:

1. Triclcium silicate (3CaO.SiO2)

2. Dicalcium silicate (2CaO.SiO2)

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3. Tricalcium aluminates (3CaO.Al2O3)

4. Tetracalcium aluminoferrite (4CaO.Al2O3.Fe2O3)

B(iii) CHARATERSTICS OF OPC 43 GRADE

1. Durable

2. Corrosion resistance

3. Low heat of hydration

4. Volume stability

5. Gigantic compressive strength

B (iv) SETTING AND HARDENING

Cement sets when mixed with water by way of a complex series of chemical reactions still only

partly understood. The different constituents slowly crystallize and the interlocking of their

crystals gives cement its strength. Carbon dioxide is slowly absorbed to convert

the portlandite (Ca(OH)2) into insoluble calcium carbonate. After the initial setting, immersion

in warm water will speed up setting. Gypsum is added as an inhibitor to prevent flash setting.

B (v) USE OF OPC 43 GRADE

The most common use for Portland cement is in the production of concrete. Concrete is a

composite material consisting of aggregate (gravel and sand), cement, and water. As a

construction material, concrete can be cast in almost any shape desired, and once hardened, can

become a structural (load bearing) element. Concrete can be used in the construction of

structural elements like panels, beams, road furniture, or may make cast-in situ concrete for

building superstructures like roads and dams. These may be supplied with concrete mixed on

site, or may be provided with "ready-mixed" concrete made at permanent mixing sites. Portland

cement is also used in mortars(with sand and water only) for plasters and screeds, and

in grouts (cement/water mixes squeezed into gaps to consolidate foundations, road-beds, etc.).

When water is mixed with Portland cement, the product sets in a few hours and hardens over a

period of weeks. These processes can vary widely depending upon the mix used and the

conditions of curing of the product, but a typical concrete sets in about 6 hours and develops

a compressive strength of 8 MPa in 24 hours. The strength rises to 15 MPa at 3 days, 23 MPa at

1 week, 35 MPa at 4 weeks and 41 MPa at 3 months. In principle, the strength continues to rise

slowly as long as water is available for continued hydration, but concrete is usually allowed to

dry out after a few weeks and this causes strength growth to stop.

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(C) CONCRETE

Concrete is a composite material composed mainly of water, aggregate, and cement. Often,

additives and reinforcements (such as rebar) are included in the mixture to achieve the desired

physical properties of the finished material. When these ingredients are mixed together, they

form a fluid mass that is easily molded into shape. Over time, the cement forms a hard matrix

which binds the rest of the ingredients together into a durable stone-like material with many

uses.

C (i) HISTORY

Famous concrete structures include the Hoover Dam, the Panama Canal and the

Roman Pantheon. The earliest large-scale users of concrete technology were the ancient

Romans, and concrete was widely used in the Roman Empire. The Colosseum in Rome was built

largely of concrete, and the concrete dome of the Pantheon is the world's largest unreinforced

concrete dome.

C (ii) CHARACTERISTICS OF GOOD CONCRETE

1. Workability

2. Freedom from segregation

3. Freedom from bleeding

4. Strength

5. Durability

6. Appearance

(D) AGGREGATES

The inert mineral materials such as sand, gravel, etc used for manufacture of concretes are

known as aggregates. Requirements Of Good Aggregates

1. It should be sufficiently strong.

2. It should be hard

3. It should be durable.

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4. It should have rough surface.

5. It should be in spherical or cubical in shape.

D (i) Classification of Aggregate

1. Coarse Aggregates

2. Fine Aggregates

Coarse aggregates – The aggregates which pass through 75mm IS sieve and retain on 4.75mm IS sieve are known as

coarse aggregates.

Fine aggregates – The aggregates which pass through 4.75 mm IS sieve and retain on 75 micron IS sieve are

known as fine aggregates.

*The research work is restricted to sand collected from the river. The sand was collected to

ensure that there was no allowance for deleterious materials contained in the sand and the size of

5mm. In this research, granite of 20mm maximum size was used.

(E) Water Water plays an important role in concrete production (mix) in that it starts the reaction

between the cement, pozzolan and the aggregates. It helps in the hydration of the mix. In this

research, the water used was distilled water.

1.4 Objective The main objective of this work is to study the suitability of the rice husk ash as a pozzolanic

material for cement replacement in concrete. However it is expected that the use of rice husk ash

in concrete improve the strength properties of concrete. Also it is an attempt made to develop the

concrete using rice husk ash as a source material for partial replacement of cement, which

satisfies the various structural properties of concrete like compressive concrete like compressive

strength.

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1. Effect of Rice Husk Ash on workability.

2. Effect on Compressive strength of concrete.

3. Comparison of result of different tests with varying proportion of RHA.

1.5 Scope of the project

It is also expected that the final outcome of the project will have an overall beneficial effect on

the utility of rice husk ash concrete in the field of civil engineering construction work. Following

parameters influences behavior of the rice husk ash concrete, so these parameters are kept

constant for the experimental work. Thus the scope of the project can be summarized as:

A. To obtain Mix proportions of Control concrete by IS method.

B. To perform the specific gravity test, sieve analysis and slump test under Indian Standard

methods. C. To conduct Compression test on RHA and Control concrete on standard IS specimen size

150 x 150 x 150 mm.

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CHAPTER 2

Literatures of Review

Al Khalaf and A.Yousif (1984) Have investigated the effect of rice husk on pozzolanic behavior of rice husk ash. They

studied the actual range of temperature required to burn rice husk to get the desired

pozzolanic product. They investigated that up to 40% replacement of cement with RHA

can be made with no significant change in the compressive strength as compared to the

controlled mix, if the rice husk is burnt under optimum temperature condition.

Ismail and Waliuddin (1996) Had worked on effect of rise husk ash on high strength concrete. They studied the effect

the rise husk ash (RHA) passing 200 and 325 micron sieves with 10- 30 % replacement

of cement on strength of HSC. Test result indicated that strength of HSC decreased

when cement was partially replaced by RHA for maintaining same value of workability.

They observed that optimum replacement of cement by RHA was 10 – 20 %.

Ramezanianpour et al. (2009, 2010) Concluded that burning rice husks at temperature below 700°C produces rice husk ashes

with high pozzolanic activity.

Ryan (1999) Investigated on Concrete durability. He in his paper through QCL group addresses two

aspects of concrete serviceability, which has been the subject of extensive recent

discussion and research: sulphate attack and chloride ion penetration. The basic

chemistry involved in each of these processes is outlined by him and differentiated and

their effects on concrete and reinforcing steel are described. His paper relied for actual

test data, showing relative performance of binder options, on experimental work carried

out by researchers at the CSIRO Division of Building, Construction, and Engineering.

Skalny et al (2002) Researched on Concrete subject to sulfate attack undergoes a progressive and profound

reorganization of its internal microstructure. These alterations have direct consequences

on the engineering properties of the material. As seen from his studies, concrete

undergoing sulphate attack is often found to suffer from swelling, spalling and cracking.

There is overwhelming evidence to show that the degradation also contribute to

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significantly reduce the mechanical properties of concrete. He studied the behaviour of

hydrated cement systems tested under well-controlled laboratory conditions is also

distinguished from the performance of concrete in service. He stated that Sulphate attack

has significant consequences on the microstructure and engineering properties of

concrete. Marked expansion and loss in the mechanical properties of the material often

accompany sulphate-induced micro structural alterations.

Prasad et al (2006) Investigated on Cement concrete which continues to be the pre-eminent construction

materials for use in any type of civil engineering structure He concluded in his

investigation the blended cements, particularly are better in Sodium Sulphate

environment. The blended cement mixes show more deterioration in Magnesium

Sulphate exposure in compared to plain cement mixes. The Magnesium Sulphate

environment is more severe than Sodium Sulphate environment. The performance of low

water/binder ratio mixes is inferior in Sulphate resistance. The little initial air curing of

mixes is beneficial for Sulphate resistance. He also stated that The deterioration of

cement mixes increases with increase in the concentration of Sulphate. The presence of

Chloride ions with Sulphate ions reduces the rate of Sulphate attack on cement mixes.

The deterioration rate of mixes due to Sulphate attack is higher at high temperature with

alternate wetting and drying cycles.

Abdullahi et al (2006) Investigated on the compressive strength of some commercial sandcrete blocks in

Minna, Nigeria was investigated. Rice Husk Ash (RHA) was prepared from burning

firewood. Preliminary analysis of the Constituent materials of the ordinary Portland

Cement (OPC) / Rice Husk Ash (RHA) hollow sandcrete blocks were conducted to

confirm their suitability for block making. He conducted physical test of the freshly

prepared mix. 150mm×450mm hollow sandcrete blocks were cast cured and crushed for

1, 3, 7, 14, 21, and 28 days at 0, 10, 20, 30, 40 and 50 percent replacement levels. He

concluded the results of test and indicated compressive strength of the OPC/RHA

sandcrete blocks increases with age at curing and decreases as the percentage of RHA

content increases.

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CHAPTER 3

METHODOLOGY

3.1 GENERAL It is also expected that the final outcome of the project will have an overall beneficial effect on

the utility of rice husk ash concrete in the field of civil engineering construction work. Following

parameters influences behavior of the rice husk ash concrete, so these parameters are kept

constant for the experimental work.

• Percentage replacement of cement by rice husk ash

• Fineness of rice husk ash

• Chemical composition of rice husk ash

• Water to cement material ratio (w/c ratio)

• Type of Curing

Also from the literature survey, it is observed that the parameters suggested by different

researchers and their results are not matching with each other. It was due to variation in

properties of different materials considered in the work. Therefore the percentage replacement of

cement by rice husk ash and method of mix design is fixed after preliminary investigation.

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3.2 FLOW CHART

Chapter

Fig-2 Flow chart depicting the methodology

COMPRESSIO

N TEST AT 7th

AND 28th

DAY

LITERATURE

PARTIAL

REPLACEMENT OF

CEMENT WITH

RHA(20%)

CONTROLLE

D CONCRETE

CASTING

CONCLUSION RESULTS

TRIAL MIX

DESIGN

PRIMARY

TEST

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CHAPTER -4

Preliminary Test

4.1:- Sieve analysis

Purpose: This test is performed to determine the percentage of different grain sizes obtained within a soil.

The mechanical or sieve analysis is performed to determine the distribution of the coarser,

larger-sized particles, and the hydrometer method is used to determine the distribution of the

finer particles.

Standard Reference: ASTM D 422 - Standard Test Method for Particle-Size Analysis of Soils

Significance: The distribution of different grain sizes affects the engineering properties of soil. Grain size

analysis provides the grain size distribution, and it is required in classifying the soil.

Equipment:

Balance, Set of sieves, Cleaning brush, Sieve shaker, Timing device.

Test Procedure:

Sieve Analysis:

(1) Write down the weight of each sieve as well as the bottom pan to be used in the analysis.

(2) Record the weight of the given dry soil sample.

(3) Make sure that all the sieves are clean, and assemble them in the ascending order of sieve

numbers (4 sieve at top and 200 sieve at bottom). Place the pan below 200 sieve. Carefully pour

the soil sample into the top sieve and place the cap over it.

(4) Place the sieve stack in the mechanical shaker and shake for 10 minutes.

(5) Remove the stack from the shaker and carefully weigh and record the weight of each sieve

with its retained soil. In addition, remember to weigh and record the weight of the bottom pan

with its retained fine soil.

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Table:3 Sieve Analysis of sand

Sieve size Weight retained % Retained % Passing

6.3 0 100

5.0 0 100

2.36 5 0.33 99.67

1.18 130 8.7 90.97

600 429 28.6 62.37

425 345 23.0 39.37

300 338 22.5 16.87

212 126 8.4 8.47

150 80 5.3 3.17

63 43 2.9 0.27

PAN 4 0.27 0

Table:4 Sieve Analysis of Gravel (20mm) :

Sieve size Weight Retained % Retained % Passing

20 0 100

13 4 0.3 99.7

10 18 1.2 98.5

6.3 119 8 90.5

4.7 70 4.7 85.8

2.36 234 15.8 70.0

PAN 40 2.70 67.3

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CHAPTER-5

MIX DESIGN

5.1 MIX DESIGN:

Mix design of concrete

Replacement of cement by 20% of RHA

Grade of concrete – M20

Type of cement – OPC 43 grade

Type of material admixture -Rice Hsk Ash (RHA)

Maximum nominal size of aggregate – 20mm

Minimum cement content – 320kg/m3

Maximum water cement ratio – 0.45

Workability – 100mm (slump)

Exposure condition – Severe

Degree of supervision –Good

Types of aggregate – Crushed angular aggregate

Maximum cement – 450 kg/m3

Specific gravity of Cement - 3.17

Specific gravity of RHA – 2.28

Replacement of cement 20% by RHA

Replacement of sand 0%

Target strength for mix proportion

fck „ = fck + 1.65 S

fck = compressive strength @ 28 days =20

S= 4 (Table no.1 IS 10262:2009)

fck‟ = 20 + 1.65 * 4

= 26.6 N/mm2

Selection of w/c Ratio

Max W/C RATIO = 0.45 [from IS456]

Adopt = 0.4

Selection Of Water Cement

Max water content for 20mm aggregate = 186 litre (for 20 to 50mm slump range)

Water content for 100mm slump = 186 + 6/100*186

25

= 186 + 11.1

= 197.1 ~ 197L

Assuming 29% W.C = 197 – 197*29/100

= 140 (approx)

Calculation Of Cement Content

Water cement ratio = 0.40

Cement content = 140/0.4 = 350kg/m3

From table No.5 of IS456 minimum cement content for severe exposure conditions

= 320kg/m3

350kg/m3 > 320kg/m3 Hence ok

Volume of coarse and fine aggregate for zone 1

Volume of C.A = 0.6

Volume of F.A = 1-0.6 =0.4 [IS 10262:2009]

Cementious Matrial Content = 350*1.10

= 385kg/ m3

Water content = 140 kg/ m3

So water cement ratio 140/385 = 0.364

RHA @20% Of Total Cementious

Material content cement = 385-385*20/100

= 308 kg/m3

Saving of cement while using RHA

= 350 – 308

= 42 Kg/ m3

RHA being utilized = 77 kg/m3

26

(a) VOLUME OF CONCRETE = 1 m3

(b) VOLUME OF CEMENT = MASS OF CEMENT/S.G OF CEMENT * 1/100

= 308/3.17 * 1/1000

= 0.0971 m3

(c) VOLUME OF RHA = Mass of RHA/s.g of RHA * 1/1000

= 77/2.28 * 1/1000

= 0.0337 m3

(d) VOLUME OF WATER = 140 * 1/1000 = 0.140 m3

(e) VOLUME OF ALL IN AGGREGATE = [a- (b+c+d)]

= [1-(0.98+0.0337+0.14)]

= 0.7293 m3

Mass of C.A = e * volume of C.A * sg of CA * 1000

= 0.7293 * 0.6 * 2.6 * 1000

= 1126.78 ~ 1127 kg

MASS OF F.A = e * volume of F.A * sg of F.A * 1000

= 751.19 ~ 751 kg

Mix proportion for 1 m3

Cement = 308 kg/ m3

RHA = 77 kg/ m3

WATER = 140 kg/ m3

F.A = 751 kg/ m3

C.A = 1127 kg/ m3

W/C Ratio = 0.45

RATIO = 1 :0.20 :0.45 :1.5: 3

VOLUME OF 1 CUBE = 0.15 * 0.15 *0.15

= 0.003375 m3

27

TOTAL CUBE IN 1 M3 = 296.2 ~ 297

MASS OF CEMENT IN 1 CUBE = 308/297

= 1.03 KG

MASS OF RHA IN CUBE = 77/297

= 0.259 KG

VOLUME OF WATER IN 1 CUBE = 140/297

= 0.47 KG

MASS OF F.A = 751/297

= 2.52 KG

MASS OF C.A = 1127/297

= 3.79 KG

Grade designation: M20

Grade ratio: 1:1.5:3

Cement used: Ordinary Portland cement

Grade of cement used: 43

Density of cement: 2400kg/m3

Calculation:-

Density= mass/volume

Mass= density* volume

Volume of mould = 0.15*0.15*0.15

Mass= (0.15)3*2400

= 8.1 kg

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Table: 5 Similarly all the following values given in the table are calculated as

above

(a) Without RHA Replacement

Material 1 cube(kg) 12 cubes(kg)

Cement 1.03 12.36

Sand 2.51 30.12

Coarse aggregate 3.79 45.48

(b) With 20% RHA replacement

Material 1 cube(kg) 12 cubes(kg)

RHA 0.251 3.012

Cement 0.779 9.348

Sand 2.51 30.12

Coarse aggregate 3.79 45.48

29

CHAPTER-6

Experimental work

6.1. Preparation of materials

Mixing:

Mix the concrete either by hand or in a laboratory batch mixer

Hand mixing:

(i)Mix the cement and fine aggregate on a water tight none-absorbent platform until the mixture

is thoroughly blended and is of uniform color

(ii)Add the coarse aggregate and mix with cement and fine aggregate until the coarse aggregate

is uniformly distributed throughout the batch

(iii)Add water and mix it until the concrete appears to be homogeneous and of the desired

consistency

6.2. Slump Test :

Procedure to determine workability of fresh concrete by slump test.

(i) The internal surface of the mould is thoroughly cleaned and applied with a light coat of oil.

(ii) The mould is placed on a smooth, horizontal, rigid and nonabsorbent surface.

(iii) The mould is then filled in four layers with freshly mixed concrete each approximately to

one-fourth of the height of the mould.

(iv) Each layer is tamped 25 times by the rounded end of the tamping rod (strokes are

distributed evenly over the cross section).

(v) After the top layer is rodded, the concrete is struck off the level with a trowel.

(vi) The mould is removed from the concrete immediately by raising it slowly in the vertical

direction.

(vii) The difference in level between the height of the mould and that of the highest point of the

30

subsided concrete is measured.

(viii) This difference in height in mm is the slump of the concrete.

Fig:3 slump test being performed

Fig:4 Before demoulding of slump mould

31

Fig:5 slump height being checked after removal of mould

Result:

The value of the slump test i.e, the height of the slump cameout to be 26 cm.

32

Fig 6: MOUDLS OF SIZE 150mm*150mm

Fig 7: casting of concrete cube

33

Fig.8,9 Tamping of concrete being done.

34

6.3. Casting:

(i) Clean the mounds and apply oil

(ii) Fill the concrete in the molds in layers approximately 5cm thick

(iii) Compact each layer with not less than 35strokes per layer using a tamping rod (steel bar

16mm diameter and 60cm long, bullet pointed at lower end)

(iv) Level the top surface and smoothen it with a trowel.

6.4: Curing:

The first batch of 12 test specimens are stored in moist air for 24hours and after this

period the specimens are marked and removed from the molds and kept submerged in

clear fresh water until taken out prior to test.

The next batch of 12 test specimen are casted and stored in moulds for 24hrs after

demoulding the first batch. After this the specimen are removed from the moulds and

kept submerged in clear water until taken out prior to test.

Precautions:

The water for curing should be tested every 7days and the temperature of water must be at

27+-2oc. We should make sure that the water should be free from any deleterious material.

35

6.5. Compression Test

Aim:

To find out the compressive strength of 24 test specimens.

Apparatus:

Compression testing machine

Specimen:

12 cubes of 15 cm size mix. M20

Procedure:

(i) Remove the specimen from water after specified curing time and wipe out excess water from

the surface.

(ii) Take the dimension of the specimen.

(iii) Clean the bearing surface of the testing machine

(iv) Place the specimen in the machine in such a manner that the load shall be applied to the

opposite sides of the cube cast.

(v) Align the specimen centrally on the base plate of the machine.

(vi) Rotate the movable portion gently by hand so that it touches the top surface of the specimen.

(vii) Apply the load gradually without shock and continuously at the rate of 140KG/cm2/minute

till the specimen fails

(viii) Record the maximum load and note any unusual features in the type of failure.

Note

Minimum three specimens should be tested at each selected age. If strength of any specimen

varies by more than 15 per cent of average strength, results of such specimen should be rejected.

Average of there specimens gives the crushing strength of concrete. The strength requirements of

concrete.

36

Calculations

Size of the cube =15cm x 15cm x 15cm

Area of the specimen (calculated from the mean size of the specimen ) =225cm

Fig10: compressive test machine

37

Fig 11: Compressive test being done at 28 days

38

CHAPTER-7

Results and Graphs

7.1 Compressive Strength Table 6. Compressive strength at different curing days

Compressive Strength (n/mm2)

DAYS (0% R.H.A) (20% R.H.A)

7 22.38 20.27

14 27.52 28.34

21 32.45 33.67

28 36.5 37.6

FIG:12 Graph Shows Variation In Compression Strength

0

5

10

15

20

25

30

35

40

7 DAYS 14 DAYS 21 DAYS 28 DAYS

0% RHA

20% RHA

39

CHAPTER -8 PRO AND CONS

(A) ADVANTAGES OF RHA

Improves the compressive strength.

RHA mixed concrete shows better bond strength as compared to opc cement.

Permeability of concrete decreases improves compressive strength.

RHA makes a role to increased resistance to chemical attack.

Show better durability of concrete.

Improves resistance to sulfate attack.

Reduce the amount of cement making concrete by 20% by weight.

Improves the corrosion resistance and strength of concrete as compared to that of OPC

concrete.

Reduces effects of alkali-silica reactivity.

Reduces shrinkage due to particle packing, making concrete denser.

Enhances workability of concrete.

Reduces heat grow through the walls of buildings.

Reduces amount of super plasticizer.

Decreases air permeability due to the filler and pozzolanic effect.

Reduces the plasticity of soil.

Increases compressive strength and decreases leachability.

Reduces material cost and emission of CO due to less cement utilization.

RHA could be used as an alternative source for high surface area silica.

40

(B) DISADVANTAGE OF RHA

Effective consumption of following RHA in cement or concrete has a great importance regarding

strength, durability and cost effectiveness of concrete up to a certain replacement percent.

Having the more benefits using RHA in cement or concrete, it shows a few disadvantages that

are mentioned below

Suitable incinerator/furnace as well as grinding method is required for burning and

grinding rice husk in order to obtain good quality ash.

Strength of concrete is reduced for larger (beyond 30%) replacement.

There is a little transportation problem.

Unburnt RHA is not suitable for concrete production.

41

(C) Conclusion

Based on the limited study carried out on the strength behaviour of Rice Husk ash, the following

conclusions are drawn At all the cement replacement levels of Rice husk ash; there is gradual increase in

compressive strength from 3 days to 7 days. However there is significant increase in

compressive strength from 7 days to 28 days followed by gradual increase from 28 days. By using this Rice husk ash in concrete as replacement the emission of greenhouse gases

can be decreased to a greater extent. As a result there is greater possibility to gain more

number of carbon credits.4. The technical and economic advantages of incorporating Rice Husk Ash in concrete

should be exploited by the construction and rice industries, more so for the rice growing

nations of Asia.

RHA based sand cement block can significantly reduce room temperature. Hence air

conditioner operation is reduce resulting in electric energy saving.

Moreover with the use of rice husk ash, the weight of concrete reduces , thus making the

concrete lighter which can be used as light weight construction material.

The pozzolonic activity of rice husk ash is not only effective in enhance the concrete

strength, but also in improving the impermeability characteristics of concrete

As the Rice Husk Ash is waste material, it reduces the cost of construction.

42

CHAPTER -9

References

G.V.RamaRaoand M.V.SheshagiriRao, “High performance Concrete with Rice

Husk Ash as Mineral Admixture”,ICI Journal, April-June 2003, pp.17-22.6. Gemma Rodriguez de Sensale“Strength Development of Concrete with Rice-

Husk Ash,”Cement & Concrete Composites 28 (2006) 158-160.7. H.B.Mahmud, B.S.Chia and N.B.A.A. Hamid, “Rice Husk Ash-An

Alternativematerial in producing High Strength Concrete,”International Conference

onEngineering Materials, June 8-11, 1997, Ottawa, Canada, pp.275-284.8. Jose James and M. SubbaRao,“Reactivity of Rice Husk Ash,”Cement and

ConcreteResearch, Vol.16, 1986, pp.296-302.9. K.Ganesan, K.Rajagopal and K.Thangavelu ,“ Effects of the Partial

Replacement of Cement with Agro waste ashes (Rice husk ash and Bagasse Ash) on strength

andDurability of Concrete,”Proceedings of the International Conference on

RecentAdvances in Concrete and Construction Technology, December 7-9,

2005,SRMIST, Chennai, India pp.73-85.

Ephraim etal, Compressive strength of concrete with RHA as partial replacement of OPC. Scholarly journal of engineering research vol.1(2)pp32-36 Cook,D.J(1996)Rice Husk Ash increment replacement material, concrete technology and design vol.3 Ed.R.Swamy, Surrey University,UK.

IS code books - 10262, 456