The Effect of Rice Husk Ash on Mechanical Properties and Durability of Sustainable Concretes

Rice husk ash (rha) is a by-product of the agricultural industry which contains high amount of silicon dioxide (sio2). in this research, for the first time in the middle east, in order to supply typical rha, a special furnace was designed and constructed in amirkabir university of technology. afterwards, xrd and xrf techniques were usedto determine the amorphous silica content of the burnt rice husk. attempts were made to determine the optimum temperature and duration of burning. results show that temperature of 650 degrees centigrade and 60 minutes burning time are the best combination. then various experiments were carried out to determine properties of concretesincorporating optimum rha. tests include compressive strength, splitting tensile strength, modules of elasticity, water permeability and rapid chloride permeability test. results show that concrete incorporating rha had higher compressive strength, splitting tensile strength and modulus of elasticity at various ages compared with that of the control concrete. in addition, results show that rha as an artificial pozzolanic material has enhanced the durability of rha concretes and reduced the chloride diffusion.