Preliminary Study on Hand-cast Lightweight Concrete Block using Raw Rice Husk as Aggregate

Abstract

Raw rice husk is an abundantly available waste material in Indonesia as one of rice producing countries. Due to rice husk is light in weight and convex in shape, this paper presents a preliminary application of raw rice husk as natural aggregate in order to make lightweight concrete blocks. Concrete specimens contained Portland Cement, filler, and raw rice husk, in which the mix proportion was in volumetric ratio, i.e 1.25 cement and 2.75 filler constantly, whereas dosage of rice husk varied from 8.5 to 10. The production of the concrete block was by mixing the ingredients together and then the mixture was casted and compacted on moulds by hand manually. Series laboratory experiments were accomplished to analyse the compressive strength and density. For this, four groups of mixes were prepared. The results have shown that the higher proportion of rice husk is the lower its compressive strength and the lighter its density. At proportion of 1,25 cement: 2,75 fillers: 8,5 raw rice husks, the compressive strength is 26.64 kg/cm2 and this satisfies the minimum standard (25 kg/cm2). Unfortunately, the density is 1,536.73 kg/m3 and it is higher than the maximum standard of 1,400 kg/m3. Thus, it is important to research further by making and testing some improved specimens with more cement, more rice husk, and less filler to fulfil strength and density.