(59b) On the Rice Husk Ash Admixing with Cement: Preparation, Characterization and Analysis

On
the Rice Husk Ash Admixing with Cement: Preparation, Characterization and
Analysis

ABSTRACT

Rice
husk is the outermost part of rice paddy, it covers about 20 to 25 % of the
rice weight. Rice husk can be converted into rice husk ash (RHA) by burning
process. The chemical composition of rice husk is found to vary from one sample
to another due to the differences in the type of paddy, crop year, climate and
geographical conditions.^[1]

Cement
is a binder, a substance used in construction that sets, hardens and adheres to
other materials, binding them together.^[2] Cements are classified as
calcium silicate and calcium aluminate cement. Calcium silicate cement is further
classified into Portland and Slag, while calcium aluminate is classified into
High alumina and Pozzolona cement.^[3]

Portland
cement is by far the most common type of cement in widespread use around the
world. This cement is made by calcining limestone (CaCO₃) with other
materials (such as clay) to 1450 °C in a kiln. Calcium oxide, so formed is then
chemically fluxed with the other materials to form calcium silicates and other
cementitious compounds. The resulting clinker is ground with a small amount of
gypsum into a powder to make 'ordinary Portland cement', the most commonly used
type of cement (often referred to as OPC).

Rice
husk ash (RHA) fulfils the physical characteristics and chemical composition of
mineral admixtures. RHA is composed mostly of silica in amorphous form (85-90%)
and it has a highly micro-porous structure which makes it suitable to replace
cement.

In
the present work, rice husk ash is prepared and characterized. A varied
percentage of RHA is used as an admixture with ordinary Portland cement in
concrete to formulate samples. Further, compressive and flexural strength
parameters of concrete are determined by Vicat test, float test, compression
test and initial & final setting times. It has been found that rice husk
ash substitution for ordinary Portland cement up to 30% is acceptable. On
increase in RHA percentage, compressive strength decreases rapidly.

References

[1]
Chandrasekhar S,
Satyanarayan KG, Pramada PN and Raghavan P. Review processing, properties and
applications of reactive silica from rice husk-an overview. Journal of
Materials Science (Norwell), 2003; 38(15):3159 - 3168.

[2]
https://en.wikipedia.org on 11 April 2017.

[3]
Jackson, N. and Dhir, R.K., Civil Engineering Materials, 4th Edition,
Macmillan ELBS, Hong Kong, 1991; pp 144 –160.