Utilization and effect of using rice husk ash for production of bricks
Department of Civi lEngineering ,KIIT Deemed to be University,KIIT
Department of Civil Engineering,KIIT Deemed to be University,KIIT
Road,Patia,Bhubaneswar 751024,[email protected]
Keywords: Rice husk ash ,Bricks ,Compressive strength ,flexural strength,durability
Abstract: There is increasing demand for producing durable construction
material.Rice husk ash(RHA) is aby product formed due to burning of rice husk.
to its high pozzolanic action the strength and durability of concrete is increased.The
main advantage of using rice husk ash is when itis added to concrete itincreases the
corrosion resistance.It also acts as agood insulator.The main objective of this article
is to investigate the feasibility of using rice husk ash in the production of bricks and
the effect of rice husk ash(RHA) content on the various properties of bricks such as
compressive strength,flexural strength,water absorption,bulk density etc.
percentage of rice husk ash(RHA) is used for studying the properties of bricks and
also analyzing the test results using rice husk ash(RHA).The utilization of rice husk
ash for production of bricks is not only cost effective but also addresses the need for
finding ways to reduce the amount of solid waste material.The investigation also
demonstrates afeasible way of using rice husk ash(RHA) as aconstituent for
producing decent quality of bricks.Increasing the rice husk ash(RHA) replacement
level decreases the strength and bulk density and increases the water absorption.
main motive of using rice husk ash(RHA) is producing bricks of decent quality.
Brick is one of the most widely used construction material in India.Bricks are made of
inorganic non-metallic material and are widely used as building component all over
the world.Bricks are considered as one of the strongest and long lasting building
materials available locally.Ordinary bricks are made of amixture of clay,which is
subjected to various processes and is differing according to the nature of material,the
method of manufacture.After itis properly prepared the clay is formed in moulds to
get the desired shape,then dried and burnt.One of the major drawback
of these conventional bricks is the environmental impact involved in the
manufacturing process.In this project,the effects of adding rice husk ash for the
production of bricks is studied.The risk husk ash is added in varying percentages,and
the effect ithas on the compressive strength,flexural strength,water absorption etc.is
investigated.There is aneed for reducing the impact of clay brick manufacturing
process on the environment and at the same time to increase the overall performance
of the brick so an alternative way is to be found out.Here,in this research the motive is
to achieve the above mentioned improvements by using the admixture for the
manufacturing process of bricks.The admixtures are added so that the bond between
the particles is increased which in turn increases the strength of the brick.The
admixtures are cementious or pozzolanic materials.The pozzolanic materials include
the traditional lime.The another type of admixture include rice husk ash,saw dust,coal
etc.which burn out when the bricks undergo firing.The advantages of adding the
1. As the organic admixtures like saw dust,rice husk ash etc.burn out the pores are
left behind in the product.Due to this itallows the control of the bulk density of the
brick products and as aresult helps in producing light weight and porous bricks.
2. The fuel and power expenditure involved in the brick manufacturing process is
3. The admixtures when added increases the strength of the brick.
2.MATERIALS USED FOR THE STUDY:
2.1 Rice husk ash:Rice husk ash(RHA) is aby product obtained by burning rice
husk.The burning conditions greatly affects the properties of rice husk ash(RHA).The
composition of rice husk ash(RHA) is 40% cellulose,30% lignin and 25-30% hydrated
silica available in non crystalline form.Rice husk ash(RHA) is agood super
pozzolanic material.Due to its high pozzolanic action the strength and durability of
concrete is increased.The rice husk ash can be used as an admixture in concrete if the
rice husk is burnt in aspecific manner.When rice husks are burnt at 500-700 °C and
kept for short time,the optimum properties of rice husk ash can be obtained.The main
motive of using rice husk ash(RHA) is producing bricks of decent quality and also the
effect itshows on the properties of bricks.The rice husk ash shows pozzolanic action
which is helpful in improving the strength.
2.2 Clay:For the brick manufacturing process clay is used.The clay used should have
i. Clay becomes plastic when itcombines with water
ii. The clay used should have sufficient tensile strength to keep the particles together
The clay is composed of silica and aluminium compounds.The clays are of two
types.They are calcareous and non calcareous clays.The calcareous clays are
composed of calcium carbonate and when burns changes to yellow or cream
colour.Non-calcareous clay consists of feldspar and iron oxides,and when itis burnt
changes to brown,pink or red,depending on the quantity of iron oxide. The presence
of silica in the clay when itis heated at 900-1200 °C will change into glassy state.This
process is called vitrification in which the clay will change into crystalline
structure.The process of vitrification takes place so that the bricks achieve sufficient
strength.It needs approximately 3cubic metres of clay soil to prepare 1000 bricks.
A brick is said to be good brick clay when pure clay and sand mixture is mixed with
water in such amanner that itcan easily be moulded and dried without cracking.Here
the manufacturing of rice husk ash is to be investigated.Silica is considered as main
constituent of the brick earth which contains in clay either as free or combined
constituent.The silica that exists as the main constituent prevents the brick from
shrinkage,cracking and hardness.In RHA ahigher amount of silica is present so that it
will lower the weight of the brick.Here the rice husk ash(RHA) has been collected
from the rice milling boiler and the rice husk is utilised as fuel for boiling paddy.After
the collection of the rice husk ash(RHA) they have been properly grinded in the
laboratory.After grinding,harmful element has been removed from rice husk
Table 1. Composition of clay and rice husk ash(RHA):
The experimental program consists of two parts:
1) Partial replacement of clay by RHA:Here the rice husk ash(RHA) is combined
with clay in various percentages ranging from 10-80% and the fundamental
properties of bricks like compressive strength,water absorption etc.are examined.
2) Full replacement of clay by waste material from various industries like RHA,lime
In this work,the waste products are used in the building construction to see the impact
on the economy of the building construction as well.Here the rice husk ash is
Measuring RHA by volume of brick clay:
The total volume of brick clay is taken.The rice husk ash(RHA) has been mixed with
brick clay in various percentage by volume.
After the evaluation of the various volumes of rice husk ash(RHA) for the various
treatments,the RHA has been combined with brick clay in the field.The thorough
moulding of brick clay has been done on the ground.
It is essential to dry the bricks prior to burning,so that they are adequately hard
enough to be handled and also kept in the burning kiln without any injury.The drying
of moulded bricks were done by resting them on their edges for sometime and then
heaped in open order in long row and stacks.
The bricks are burnt so that the hardness and strength is achieved.The burning of
bricks also increases the density.These bricks that are experimented have been burned
in clamps where the temperature is very high and itis increased to about 2100 °F.
4.1 SPECIFIC GRAVITY:
The specific gravity test for all the materials were conducted utilizing the pycnometer
for all the samples passing through 4.75mm IS sieve.
TABLE NO.2. SPECIFIC GRAVITY OF MATERIALS USED
5.1 COMPRESSIVE STRENGTH TEST:
The compressive strength of the samples prepared was evaluated using compression
testing machine.In order to get good results for this research three samples of each
composition were experimented and the average of the result is found out and also it
Table no.2 Compressive strength test results
1 Rice husk ash 0.45
2 Clay 2.25
1 100% clay 4.938
2 95% clay + 5% Rice husk
3 90% clay + 10% Rice husk
4 85% clay + 15% Rice husk
5 80% clay + 20% Rice husk
6 75% clay + 25% Rice husk
Fig 1. Compressive strength of Rice husk ash brick
5.2 Water absorption test:
The water absorption test of brick is stated as the weight of water,indicated as a
percentage of the dry weight,which is adopted by agiven method.A 24 hour cold
water immersion test was performed so that the water absorption test of the samples is
produced.In order to get good results 6samples of each composition were
experimented and the average of the results is tabulated.
Table No.3 Water absorption test results
Sl No. Type of sample Water absorption(%)
1 100% clay 4.75
2 5% clay +95% rice husk ash 8.16
3 10% clay + 90% rice husk
4 15% clay + 85% rice husk
5 20% clay + 80% rice husk
6 25% clay + 75% rice husk
Fig 2Water absorption of Rice husk ash bricks
5.3 Bulk Density Test:
The determination of bulk density of the samples were done by taking into account
the dry weight and the gross volume of all the six samples to get good results.The
average of these results are tabulated.
Table No.3 Bulk density test results
(Kg per cubic metre)
1 100% clay 1828.707
2 95% clay +5% rice husk ash 1811.157
3 90% clay + 10% rice husk
4 85% clay + 15% rice husk
5 80% clay + 20% rice husk
6 75% clay + 25% rice husk
Fig 3Bulk density of Rice husk ash bricks
The following conclusions were drawn from the experimental results that we got are
1) The clay burnt bricks were prepared with rice husk ash and these bricks showed
similar appearance in comparison to conventional clay bricks.
2) The bricks where rice husk ash is utilised as admixture shows that the bricks
experience higher percentage of water absorption in comparison to conventional
3) The bricks with rice husk ash as admixture experienced aslight increase in
compressive strength with varying percentages of admixture.
4) The bricks where rice husk ash is used as admixture can be made of different
shapes or sizes so that they are useful in building construction.
5) The RHA bricks are prepared easily because the manufacturing process is simple
and also the machinery needed here is easily available.
6) The RHA bricks are also considered economical so they can be utilised in
7) The density of the rice husk ash(RHA) bricks decreases with higher percentages
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