Rice husk ash (RHA) is a good substitute for gypsum, the popular white cement with trade name of molda 3 used in producing plaster of Paris (POP) ceiling boards. The research showed how rice husk (RH), an industrial waste materials is optimized by substituting it for gypsum used for producing ceiling board, hence converting waste to wealth. Gypsum is an expensive material used for manufacturing POP boards. RH is an industrial waste that pollutes the environment and causes enormous difficulty of disposing appropriately without causing any form of occupational health, safety and environmental hazard. Its organic property is converted to inorganic pozzolanic substance when burned at a very high temperature. The ashes exhibited an inorganic pozzolanic property that makes it to behave like cement and hence a good substitute for gypsum. 10%, 20%, 30% and 40% of the molda 3 was replaced with RHA and tested for setting time, hardness and compressive strength at each substitution. Each new percentage mix was used in the production of POP-RHA boards. The crushing strength of each mix was determined in 7, 14, 21, and 28 days respectively and the result compared to that of 0% RHA control mix. The results showed a correspondingly steady increase in strength according to the percentage mix. The density of the POP-RHA boards reduced as the percentage of the RHA increased. The aesthetics was relatively good. Improved resistance to fire, chloride and sulphate attacks are expected. The setting time of the new mix increased with increase in RHA content. Ultimately, minimization of cost and resources to maximise profit is achieved from the industrial waste materials.
Rice husk ash, Plaster of Paris, gypsum, compressive strength, setting time, molda 3
