Strength Properties of Lightweight Foamed Concrete Incorporating Waste Paper Sludge Ash and Recycled Concrete Aggregate

Abstract

A rapid growth in concrete industry is known to leave an enormous environmental footprint on planet. As the amount of cement being produced continues to rise, it results the high levels of carbon dioxide. In the meantime, a growing development in construction sector creates the sheer volumes of construction waste, mainly concrete waste. Thus, the present study aims at correlating the strength response to the contribution of using waste paper sludge ash (WPSA) and fine recycled concrete aggregate (FRCA) as an alternative of cement and natural fine aggregate substitute in the manufacturing of lightweight concrete (LWC). The different levels of WPSA and FRCA which are 0, 5, 10, 15, 20 and 30 % to cement and sand weight respectively were adopted. In this investigation, the densities of the foamed concrete used varied between 1400 and 1800 kg/m3. The results found that the presence of proportion of WPSA had reduced the compressive strength of foamed concrete. It is revealed that the compressive strength of foamed concrete with addition of FRCA attained favourable strength at the optimum replacement of 5 and 15 % for density of 1400 and 1800 kg/m3 respectively. It also showed that 1800 kg/m3 concrete that contained a combined 20 % WPSA and 30 % FRCA recorded higher strength than that of control specimen. The results confirmed that the density and different replacement level of WPSA and FRCA have influenced in the strength of foamed concrete.