Pozzolana from Rice Husk Ash

Numerous patents, publications, reviews and reports on the beneficial utilization of rice husk ash have appeared during last few decades [Proceeding of Joint UNIDO-ESCAP-RCTT-PCSIR Workshop on Production of Cement Like Materials from Agro-waste, p 135-49, 1979]. In India rice husk has been put to use in some specific areas as renewable source of energy, development of pozzolanic/cementitious materials, filling materials etc. The suitability of rice husk ash as a soil stabilizer were also studied by Okereke of Nigeria [Housing Science, Vol. 18(1), p 23-42, 1991] and he claimed that rice husk ash has some pozzolanic properties which with little addition of cement can effectively stabilizer lateritic soil. One of the earlier reference to potential benefits of using rice husk ash for making cement was published in 1956. [Agricultural Experimental Station, Louisiana State University, Bull. No.507, 1956]. The characteristics of rice husk ash were studied in relation to utilization of the ash in cement by El-Didamony and others [Arab Gulf J. Sci. Res., Vol. 5(1), p 45-57, 1987]. He reported that the rice husk fired at ≤700ºC gives amorphous silica whereas crystabalite is formed at higher temperatures. In 1971, Mehta mentioned rice husk ash as one of the materials which could react with lime and he showed that the silica in rice husk ash can be maintained in a highly pozzolanic state if temperature of combustion is kept below 700ºC and if the ash is not held too long at the high temperature [Rock Products (Chicago), Vol. 74(5), p 120, 1971]. The ash, consisting mostly of silica was found to completely amorphous, porous and easy to grind. The surface area of the lightly ground product was 55m²/kg and it became the basis of production of both lime pozzolana and portland pozzolana type cements possessing excellent strength and durability characteristics. Chopra has developed an openwork brick incinerator with metal mosquito netting inside to retain the husk [Proceeding of Joint UNIDO-ESCAP-RCTT-PCSIR Workshop on Production of Cement Like Materials from Agro-waste, p 135-49, 1979]. A ratio of 1:2 of lime to rice husk ash showed the mortar strength of about 4mN/m² with 28 days of aging.