Permeability of Rice Husk Ash Concretes

At present, for a variety of reasons, the concrete construction industry is not sustainable. The use of industrial or agricultural by-product substitutions for cement has greatly contributed to sustainable development practices. 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. Rice Husk Ash (RHA) is a by-product of the agricultural industry which contains high amount of silicon dioxide (SiO2).For many decades, the concretes incorporating RHA as an artificial Pozzolan have been noticed for their 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 reactions 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 content of RHA. The results show that RHA as an artificial pozzolanic material has increased the strength and reduced chloride permeability leading to higher durability.

Keywords:

RHA , Durability , Special furnace , RCPT