Influence of poly-lactic acid on the properties of perlite concrete

This paper is about the development of a stable and reproducible ultra-lightweight concrete with the inclusion of expanded poly-lactic acid aggregate. In total, nine mixtures were prepared by partially replacing expanded perlite (EP) aggregate with expanded poly-lactic acid (EPLA) and expanded polystyrene (EPS) to 0%, 30%, 40% and 60% by aggregate volume. The resutls of EPLA concrete were compared to the EPS concrete with identical mix proportions to evaluate the performance of the proposed concretes. The mechanical properties, thermal conductivity, fire resistance, electrical resistivity, setting time, exothermic reaction, and microstructural properties of the concrete were studied and discussed. The results reveal that the replacement of EP with EPLA causes a considerable reduction in mechanical strength of concrete. It was found that the chemical reaction of EPLA in the highly alkaline environment of cement causes significant changes in the microstructure of concrete. A large amount of calcium carbonate was found as hydration products of EPLA concrete. The carbon dioxide production and heat release rate of EPLA concrete in a fire is much lower than that of concrete containing expanded polystyrene (EPS). Contrary, a higher carbon monoxide production was observed in samples containing EPLA. The electrical resistivity and water absorption ratio of concrete increased with an increase in EPLA volume.