Effect of curing condition on strength and elastic modulus of lightweight high-strength concrete

This paper presents results of an experimental study that investigated the influence of various curing conditions on major mechanical properties of lightweight high-strength concrete (LWHSC). A LWHSC mix with a unit weight of 1950 kg/m(3) (121.7 lb/ft(3)) is cured under seven different conditions consisting of: air cured at 13 C (55 F) (AL) and 24 C (75 F) (AH); moist-cured under polyethylene sheet at 13 C (55 F) (AL) and 24 C (75 F) (PH); moist-cured with 100 percent humidity at 13 C (55 F) (ML); and submerged in water at 13 C (55 F) (SL) and 24 C (75 F) (SH). The compressive and splitting tensile strength and elastic modulus were determined at 7 and 28 days. The results indicate that the PH and SH curing conditions are capable of producing the highest compressive strength. The difference in the strength at 28 days between these conditions and the other conditions ranges up to 14.5 MPa. The tensile strength for PH and SH conditions, similar to compressive strength are higher than the strength for the other conditions at 7 days. The curing condition however, does not significantly influence the tensile strength at 18 days. LWHSC cured under a PH condition provides the highest elastic modulus, which is 16 percent (4 GPa) higher than the average elastic moduli obtained by other conditions. Regardless of curing conditions, over 90 percent of the elastic modulus value with respect to that at 28 days develops at 7 days of curing, except for the PH condition. The ACI 318 equation overestimates elastic modulus by 28 percent.