Workability and strength of lightweight aggregate concrete with rice husk ash

High strength lightweight concretes are usually produced by combining good quality artificial lightweight aggregates with a high strength binder. The latter can be achieved by using silica fume and a superplasticizer. In doing so, lightweight aggregate concretes of very high strength can be obtained. However, silica fume is relatively scarce and expensive compared to Portland cement and to other pozzolanas. It is therefore replaced by rice husk ash in this paper. The presented results indicate that the use of rice husk ash leads to enhanced resistance to segregation of fresh concrete and to increased strength compared to a control mixture with Portland cement alone. With the use of rice husk ash and superplasticizer, concretes with a compressive strength up to 61 MPa at 90 days, and with a dry density lower than 1800 kg/m(3) can be made.