this project was done with help of few members, in this project, we have replaced cement partially with fly ash and silica fumes, and tested the cubes with different mix and at different time of curing period

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USE OF FLY ASH AND SILICA FUME AS A
PARTIAL REPLACEMENT OF CEMENT IN
CONCRETE.
PROJECT REPORT
Submitted for the course: Advanced Concrete Technology (CLE2007)
By
GAURAV JAIN 15BCL0028
DEEPAK KUMAR 15BCL0102
HIMANSHU KUMAR AGRAHARI 15BCL0286
JAIN CHETAN VINAY 15BCL0320
KENI ANEESH ASHESH 15BCL0343
ABHISHAKE DUTTA 15BCL0347
Slot: G2+TG2
Name of faculty: Dr. BALAMURUGAN S
November, 2016

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School of Civil and Chemical Engineering
J Component Project
ADVANCED CONCRETE TECHNOLOGY (CLE2007)
It is certified that the project entitled “USE OF FLY ASH AND SILICA FUME AS A PARTIAL
REPLACEMENT OF CEMENT IN CONCRETE.” is the bonafide work for J component of
Advanced Concrete Technology by the following students under my supervision in G2+TG2 slot
during the Fall Semester -2016 at V.I.T. University, Vellore-632 014. The contents of this Project
work, in full or in parts, have neither been taken from any other source nor have been submitted for
any other CAL course.
Date:
Place: VIT, Vellore.
Gaurav Jain
Deepak Kumar
Himanshu Kumar Agrahari
Jain Chetan Vinay
Keni Aneesh Ashesh
Abhishake Dutta
Signature of Faculty:
Dr. BALAMURUGAN S

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ACKNOWLEDGEMENT
First and foremost, we thank God for his guidance and for blessing us with special people who
helped and supported us so much and for so long. We would also like to thank our Advanced
Concrete Technology faculty member, Professor Balamurugan S, who took keen interest in helping
us in our project work. Therefore, we, would like to acknowledge sir for his guidance and
inspiration provided during the implementation of the project, without whose dignity, the work
would have been unaccomplished. We would also like to thank all of our friends for their
collaboration, patience and co-ordination in the work with us which eventually bore fruits and gave
proper shape to this project.
We would also like to thank our wonderful parents, and siblings for everything they had to go
through so I can be where I am today.

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OBJECTIVE
Our main objective while going about our project was to replace the energy-consuming Portland
cement with fly ash and silica fume.
INTRODUCTION
 Fly ash is what remains after power plants burn coal to produce energy. This fine ash
originally considered waste material is now considered a “green” product.
 Fly ash makes the concrete more workable and less permeable. Concrete made with fly ash
requires less mix water, and bleeds less than Portland cement concrete.
 Also, by using fly ash the consumer can save some money because fly ash is less expensive
than cement.
 In addition to greater strength, workability, and cost savings, another benefit of fly ash is that
it lowers the hydration temperature of concrete and prolongs the setting time.
 Similarly silica fume results from smelting in the silicon and ferro-silicon industry.
 Addition of silica fume to concrete improves its durability through reduction in the
permeability and refined pore structure, leading to a reduction in the diffusion of harmful
ions, reducing calcium hydroxide content, which results in a higher resistance to sulphate
attack.
 Adding silica fume to concrete significantly reduces bleeding, blocking the pores of fresh
concrete and high early compressive strength while not significantly increasing the unit
weight of concrete.
INTRODUCTION
 Properties and Use of Fly Ash in Portland Cement Concrete”-R. 0. Lane
Concrete International Volume: 4 Issue: 07 Pages: 81-92
This paper focuses on the physical and chemical properties of fly ash and their effects on
freshly mixed and hardened concrete.
 “Use of fly ash in Concrete”- Halstead, W J
Transportation Research Board ISSN: 0547-5570
This paper summarizes available information concerning the use of fly ash in hydraulic-
cement concrete, and attempts to establish consensus concerning a number of applications
relating to highway construction.

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 “Use of Fly Ash in Concrete”- Paul J. Tikalsky and Morris V. Huffman
American Concrete Institute ACI 232.2R-96
This report gives an overview of the origin and properties of fly ash, its effect on the
properties of portland-cement concrete, and the proper selection and use of fly ash in the
production of portland-cement concrete.
The report contains information and recommendations concerning the selection and use of
Class C and Class F fly ashes.
 “Effect Of Silica Fume On Strength And Durability Parameters Of Concrete”- N. K.
Amudhavalli, Jeena Mathew
International Journal of Engineering Sciences & Emerging Technologies, August 2012.
ISSN: 2231 – 6604
The main parameter investigated in this study is M35 grade concrete with partial
replacement of cement by silica fume by 0, 5, 10,15and by 20%. This paper presents a
detailed experimental study on Compressive strength, split tensile strength, flexural strength
at age of 7 and 8 day.
 “Effect of Partial Replacement of Cement by Silica Fume on Hardened Concrete”-Dilip
Kumar Singha Roy, Amitava Sil
International Journal of Emerging Technology and Advanced Engineering
This paper features an experimental study on the nature of SF and its influences on the
properties of fresh and hardened concrete. In the present study, an attempt has been made to
investigate the strength parameters of concrete made with partial replacement of cement by
SF.
MATERIALS USED:
 Fly Ash.
 Silica fume.
 Cement OPC 53 grade conforming to IS8112.
 Fine aggregate (Sand).
 Water.
INSTRUMENTSUSED:
 Vicat apparatus to find the consistency so that we can calculate the water content.
 Concrete compression machine to find the compressive strength.
 Cubes of size 7.06cmx7.06cmx7.06cm.
 Curing tank.
 Tamping rod.

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METHODOLOGY
• There are 4 mixdesigns used in this investigation as indicated in the table. The mix were
made with a cement-to-fine aggregate ratio of 1:3.
• First batch was the control cube with 100% cement.
• The water content was found by performing the consistency test.
• To attain well grade fine aggregate we took the fine aggregate passing retained on 1.18mm,
600 micron and 90 micron.
• All the dry constituents are first mixed and then water is added. After it attains a
homogeneous and uniform consistency we divide the mixture into 3 parts and pour the first
part into a 70.6mm*70.6mm*70.6mm greased cube.
• After compacting the mould by applying 25 tamping of the rod we repeat the procedure for
other two layers.
• For each mixture we do 3 cubes and take the average compressive strength of the cubes after
7, 28 and 56 days.
Cement Content (%) 100 76 56 36
Fly Ash Content (%) 0 20 40 60
Silica fume (%) 0 4 4 4
Water content (P) 32 33 34 36.5
We will add water by using the formula
Water content= (P/4+3)* total weight of all the material including cement, fine aggregate and
pozzolanic material.
As we were casting 6 cubes in a batch this value was 4800.

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RESULT AND DISCUSSION
Cement Content (%) 100 76 56 36
Fly Ash Content (%) 0 20 40 60
Silica fume (%) 0 4 4 4
Date of casting 7th sept 8th sept 9th sept 12 sept
Compressive strength
after 7 days(N/mm2)
16.85 15.04 13.04 9.02
Compressive strength
after 28 days(N/mm2)
25.07 26.08 21.86 12.63
Compressive strength
after 56 days(N/mm2)
28.56 36.89 30.64 19.89
Compressive strength at 7
days(N/mm2)
Compressive strength at 28
days(N/mm2)
Compressive strength at 56
days(N/mm2)
0 % replacement 16.85 25.07 28.56
20 % replacement 15.04 26.08 36.89
40 % replacement 13.04 21.86 30.64
60 % replacement 9.02 12.63 19.89
0
5
10
15
20
25
30
35
40
CompressiveStrength(N/mm2)
No of Days
Graph showing the variation ofcompressivestrength for different
% replacement
0 % replacement 20 % replacement 40 % replacement 60 % replacement

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COMPARING THE COMPOSITIONOF FLY ASH AND SILICA FUME
 Fly ash, being primarily pozzolanic, can actually replace a percentage of the Portland
cement, to produce an even stronger, more durable and more environment friendly concrete.
 The initial compressive strength is low but as days pass, fly ash concrete gains more strength
and eventually has a lot more strength as compared to normal Portland cement.
 Significantly reduces the release of CO2 into the atmosphere.
 The main benefit of fly ash in concrete is that it not only reduces the amount of non-durable
calcium hydroxide (lime), but in the process converts it into calcium silicate hydrate (CSH),
which is the strongest and most durable portion of the paste in concrete.

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Pazzalonic action refers to the generation of the CSH gel which is responsible for the strength of the
concrete.
DISADVANTAGES
 Cannot be used for structures requiring shorter setting time, a demand which is expected by
most of the engineers and builders.
 It is very difficult to use in winter season due to further increase in already longer setting
time.
 Difficult to control colour of cement containing fly ash. Hence, a bit problematic to use
where cosmetic quality plays a significant role.
CONCLUSION
 Fly ash thus holds a vast potential for improving the modern day concrete when it comes to
quality in the long term. In spite of being an industrial waste, it can improve durability and
reduce heat of hydration.
 The prospects of fly ash are still being underused even today. Thus keeping in mind about
environmental concerns and its indispensability as a mineral admixture, the values of fly ash
should be effectively garnered.
 Using of Silica fume is important in infrastructure sectors in whole of the world. To improve
concrete admixtures with silica fume and to get required details of stable buildings that are
high early compressive strength, enhanced durability, toughness, protecting structure
members and reinforcement from corrosion.

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INFERENCE
As we are using 53 grade ordinary Portland cement the strength after 28 days should be 53 N/mm2.
But in our case this is not so. The main reason may be either improper compaction, lumps in
cement, may be due to excess water.
REFERENCES
 Concrete technology(theory and practice) –M.S Shetty
 www.civilblog.org
 www.theconstructor.org
 IS: 516 – methods of test for strength of concrete.
 IS: 2250 – compressive strength test for cement mortar cubes.