Develop a low cost and effective methodology to improve the physical properties of recycled aggregates with the use of rice husk ash- cement slurry

Abstract

This paper represents a surface treatment method for recycled coarse aggregates (RCA) based on a coating technique where different slurry ratios (i.e., Liquid: Solid) having varying proportions of rice husk ash (RHA) and cement was used. The different slurry ratios used in this research are 0.625, 0.750, 0.875 and 1.000. The solid compositions in the slurry were varied by varying the cement: RHA composition as followed 20%: 80%, 40%: 60%, 50%: 50%, 60%: 40%, 80%: 20% and 100%: 0%. By observing the results it can be seen that when the RHA replacement level in the solid composition of the slurry is increased the water absorption capacity of the treated RCA (TRCA) increases plus the strength factor of the coating decreases, hence it‟s suggested that RHA replacement should not exceed 40% in the slurry used to treat RCA. Furthermore it can be observed that when the slurry is thinner the water absorption capacity of the TRCA reduces. It can be further stated that there isn‟t an effect on the water absorption capacity of TRCA beyond 7 days of curing. Hence it‟s best to use a thin slurry that has a solid composition where the RHA replacement level does not exceed 40%.