Strength properties of lightweight concrete made with LECA grading

This study examined the structural behaviour of lightweight concrete (LWAC) made with different gradings of lightweight aggregates (expanded clay aggregates LECA) and normal weight aggregates with the aim to investigate the effect of partial replacement of the normal weight aggregates with different gradings of the LECA. The paper focused on performance parameters such as compressive strength (f'(c)), splitting tensile strength, unit weight and workability of concrete. The LWAC was compared to normal aggregate concrete with different cement contents. The results indicate that both LECA aggregate size and its percentage and the cement content have significant effects on the properties of lightweight concrete. A critical finding of the study is related to the tensile strength (f(t)) of LWAC, which was shown to be overestimated if determined using the recommendations made by the Dutch code VBC 1990; a new correlation between f(t) and f'(c) is presented in this paper. In spite of the good results obtained for this type of LWAC relative to normal weight concrete, there is no certain mix proportion that can be generally used, as is the case for normal weight concrete, and more studies are still needed to ensure its optimal proportions.