Concrete with highly active rice husk ash

The overall aim was to investigate the effect of highly active rice husk ash (RHA) produced by an industrial furnace on some properties of concrete. The strength, pore volume and pore distribution of concrete and the Ca(OH)2 content in concrete were investigated by JIS A 1108 (Method of test for compressive strength of concrete), a mercury instrument porosimeter, and the thermogravimetric analysis, respectively. The results show that, with RHA replacement of cement, the compressive strength of concrete is increased evidently; the average pore radius of concrete is greatly decreased, especially the portion of the pores greater than 20 nm in radius is decreased while the amount of smaller pores is increased, and the more the RHA replacement, the less the amount of Ca (OH)2 in concrete. The latter two results are the main reasons for the strength enhancement of concrete.