Effect of autoclave curing on the compressive strength and elastic modulus of lightweight aggregate concrete

In this study, three types of concrete specimens of different proportions were prepared and mixed at water-to-binder ratios (w/b) of 0.28, 0.32, and 0.40. The specimens were normal-weight concrete (NWC), lightweight sand concrete (LWSC), and lightweight aggregate concrete (LWAC). The specimens then underwent standard curing and autoclaving for 3, 7, 28, and 56 days. Comparisons were made among the specimens in terms of compressive strength and elastic modulus. Experimental results show that after standard curing, the compressive strength of NWC, LWSC, and LWAC at w/b=0.28 were 62.7 MPa (100 %), 54.7 MPa (87 %), and 39.4 MPa (63 %), respectively, Indicating that greater particle density aggregates led to better compressive strength. After 56 days of autoclaving, NWC showed the highest compressive strength, followed by LWSC and LWAC. The compressive strength and elastic modulus at Day 28 and Day 56 of autoclaving were close to those at Day 91 and Day 120 of standard curing, respectively; this trend was observed in both NWC and LWSC. The moduli of elasticity for NWC, LWSC, and LWAC at different curing ages were 20.35-33.20, 17.98-24.02, and 10.58-12.95 GPa, respectively, which decreased with increasing lightweight aggregate content in the concrete Copyright © 2009 by ASTM International.