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Replacement of Cement with
Rice Husk Ash in Concrete
PAL SHWETA PRAKASH
This research work was experimentally carried out to
investigate the effects of partially replacing ordinary Portland
cement (OPC) with our local additive Rice Husk Ash (RHA)
which is known to be super pozzolanic in concrete at optimum
With this research work, the problem of waste management of
this agro-waste will be solved.
The compressive strength value at 7,14,21 and 28 days is found
to be 20.27, 28.34 ,33.67,37.60N/mm2 at the replacement
percentage of 20 %. The compressive strength value compared
favourably with the controlled concrete strength of 22.38, 27.52,
32.45 and 36.5N/mm2 at a mix ratio of 1:1.5:3.
Rice husk ash is an agricultural waste which is produced
in millions of tons. Rice husk ash (RHA) is obtained by
the combustion of rice husk and has been found to be
Thus, due to growing environmental concern and the
need to conserve energy and resources, utilization of
industrial wastes as supplementary cementing materials
has become an integral part of concrete construction.
RHA is very reach in silicon dioxide which makes it
very reactive with lime due to its non-crystalline silica
content and its specific surface. It has about 85-90%
This study investigated the engineering properties of
RHA as a material for concrete production. The
results shows that RHA is a super pozzolan and very
suitable as a partial replacement of OPC
o 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.
o Cement - Ordinary Portland cement (OPC) of 43 grade was used in
which the composition and properties is in compliance with the Indian
o 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.
o 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. In
this research, granite of 20mm maximum size
Rice Husk Ash (R.H.A)
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.
Properties of Rice Husk Ash
i. Physical Properties
ii. Chemical Properties
Result of Slump Test
The value of the slump test i.e, the height of
the slump came out to be 26 cm.
Casting of cubes
1. MODULS OF SIZE
2. casting of concrete cube
Tamping of concrete being done.
After 24 hour we open the mould and take
away the cubes.
Then we put the cubes in the water tank for
And one by one we take away the cubes from
the and the tank the do the compression test.
Compressive Strength of RHA Concrete
o The compressive strength of RHA concrete was
investigated at 7 ,14 ,21,28 days curing age.
The summary of the results are presented
graphically and tabulated in a figure 1 and 2
below for the percentages of RHA.
Based on the limited study carried out on the strength
behaviour of Rice Husk ash, the following conclusions are
1. 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.
2. 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.
3. 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
4. RHA based sand cement block can significantly reduce room
temperature. Hence air conditioner operation is reduce
resulting in electric energy saving.
5. 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.
6. As the Rice Husk Ash is waste material, it reduces the cost of
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Journal of Cement Composites and Light Weight Concrete. 6(4).
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Malhotra (Ed) (1992). Proceedings of the International Symposium on
Advances in Concrete Technology. Atthens, Greece.
Mauro, M, et al (2004). Influence of Rice Hush Ash on Mechanical
Characteristics of Concrete. ACI.
Mehta, PK (1992) Rice Husk Ash a Unique Supplementary Cementing Material,
Mehta, PK, (1999) “Concrete Technology for Sustainable Development”.
Concrete International, 21(11).
Mehta, PK, Folliard, KJ (1995) “Rice Husk Ash a Unique Supplementary
Cementing Material Durability Aspects”. USA.
Michigan Tech Master’s International Program in Civil and Environmental