EFFECT OF RICE HUSK ASH AND CRUMB WASTE RUBBER TIRES TO MICROSTRUCTURE AND STRENGTH OF CONCRETE

Abstract

: The study aimed to seek for alternative use of crumb waste rubber tires (CWRT) in construction to
lessen its environmental impact. Its use as a component in concrete has resulted in reduced mechanical and
durability performance. On the other hand, rice husk ash (RHA), when used in conjunction with ordinary Portland
cement improves the mechanical properties of concrete. Hence, to exploit this influence of RHA to strength, this
study incorporated RHA in concrete to compensate for the strength reduction brought about by the inclusion of
CWRT, as partial replacement to fine aggregates. RHA is also a by-product of agricultural waste thus, to maximize
its potential as a cementitious material, an optimized process was developed for the study. Controlled burning and
grinding were employed to maximize the pozzolanic properties obtained from RHA. Chemical treatment of CWRT
has not resulted in a significant increase in strength for mortar specimens thus, treatment was not employed for
CWRT used in concrete. Compressive strength was tested for concrete with varying CWRT ranging from 5 to
20% fine aggregate replacement. RHA replacement of cement was fixed at 10% based on the result of an earlier
related study. Concrete with 10% RHA and 5% CWRT was found to be the optimal mix with a 9.5% increase in
strength compared to normal concrete.