The study of using rice husk ash to produce ultra high performance concrete

The limited available resource and the high cost of silica fume (SF) in producing ultra high performance concrete (UHPC) give the motivation for searching for the substitution by other materials with similar functions, especially in developing countries. Rice husk ash (RHA), an agricultural waste, is classified as “a highly active pozzolan” because it possesses a very high amount of amorphous SiO2 and a large surface area. The possibility of using RHA to produce UHPC was investigated in this study. The result shows that the compressive strength of UHPC incorporating RHA, with the mean size between 3.6 μm and 9 μm, can be achieved in excess of 150 MPa with normal curing regime. The interesting point is that the effect of RHA on the development of compressive strength of UHPC is larger than that of SF. Besides, the sample incorporating the ternary blend of cement with 10% RHA and 10% SF showed better compressive strength than that of the control sample without RHA or SF. This blend proved to be the optimum combination for achieving maximum synergic effect.