Effects of silica fume and rice husk ash on the properties of heavy weight concrete

Considerable efforts are being taken worldwide to utilize local natural waste and by-product materials in making concrete, such as silica fume (SF) or rice husk ash (RHA) as supplementary cementing materials to improve concrete properties (durability, strength, etc.). The effect of using SF or RHA as a partial replacement for cement has been investigated. Ilmenite and baryte were used as heavy aggregates while gravel was used as a reference normal aggregate. Physical, mechanical, and shielding properties of different types of heavy weight concrete were studied. The durability of the studied concrete was investigated. The study was extended to investigate the microstructure, the infrared and thermal analysis, and the effect of absorbed gamma radiation of the studied concrete types. Results showed that ilmenite concrete mixed with 15% SF had the highest density; compressive, tensile, flexural, and bond strengths; modulus of elasticity; and attenuation coefficient values. Concrete mixed with RHA had good resistance to sulfate attack, while concrete mixed with SF had better resistance to sulfate attack. There was no significant effect for either SF or RHA on the concrete gamma attenuation coefficient. Results showed that concrete mixed with RHA had higher mechanical and physical properties than that mixed without any additives but lower properties than that mixed with SF.