Effect of aggregate size and polyethylene sheet curing on me-chanical and microstructural properties of lightweight expanded clay aggregate concrete

Abstract

This study assessed the effect of lightweight expanded clay aggregate (LECA) grain size and curing with polyethylene concrete curing film (PCCF) on microstructure, interfacial transition zone (ITZ), and compressive strength of structural lightweight aggregate concrete (LWAC) produced with two different Dmax (16 or 22.4 mm). To this end, 2 series of normal weight aggregate concretes (NWAC) and 6 series of LWAC incorporating 40% by vol. unprewetted LECA having (0-3, 3-8, or 8-16 mm) grain sizes were evaluated by using unit weight, compressive strength tests at 1, 7, and 28 days and SEM-EDX observations. Preventing the moisture loss from fresh concrete through PCCF curing had positive effects on compressive strength up to 14 and 9% for 1 and 28 days respectively. Shell thickness of LECA considerably increased with the decrease in LECA grain size. Thus, the compressive strength of LECA and LWAC increased by the decrease in LECA grain size. LWAC containing 0-3 mm LECA, achieved up to 21% higher compressive strength to weight ratio compared with the NWAC with the aid of the pozzolanic reactivity of fine LECA particles.