EVALUATION OF MECHANICAL PROPERTIES AND DURABILITY OF CONCRETES CONTAINING RICE HUSK ASH

Replacement of cement with pozzolan in the production of concrete not only improves the mechanical properties and durability of concrete but also decreases the amount of consumed cement in construction projects as well. For many decades, the concretes incorporating Rice Husk Ash (RHA) as an artificial Pozzolan have been noticed for its qualities and properties. The ash remaining from burning rice husk with high specific surface, decreases porosity and permeability and increases durability of concrete as a result of considerable pozzolanic activities and chemical activities with Calcium Hydroxide. In this paper, in order to supply typical RHA, a special furnace was designed and constructed in Amirkabir University of Technology. XRD and XRF techniques were used to determine the amorphous silica content of the burnt rice husk. Consequently, temperature of 650 degrees centigrade and 60 minutes burning time was found to be the best combination. Then, various experiments were carried out to determine properties of concretes incorporating optimum RHA. The results show that RHA as an artificial pozzolanic material has increased the strength and reduced chloride permeability leading to higher durability. As an example, the tensile strength increased up to 13% after 28 days and up to 23% at 90 days.