The relationship between curing regime and mechanical properties of controlled low-strength material

This paper outlines research conducted on controlled low strength material (CLSM) to examine the effects of curing condition and water-cementitious material (w:cm) ratio on its engineering properties, including compressive strength, elastic modulus, indirect tensile strength, drying shrinkage, and setting time. Two different curing regimes were used to assess compressive strength and indirect tensile strength. In the first curing regime, continuous curing was applied in a 100% relative humidity environment and at a temperature of 70 degrees F (21.1 degrees C). In the second, continuous curing was used in a 50% relative humidity (RH) environment at a temperature of 70 degrees F (21.1 degrees C). Curing the specimen at 50% RH environment remarkably decreased the rate of strength gain when compared to the 100% RH environment. The compressive strength and indirect tensile strength of CLSM, as expected, also increased as the w:cm ratio decreased from 1.0 to 0.8 for the same curing conditions and decreased as the cement amount was lowered in the mix. The bar linear shrinkage tests showed that shrinkage strain at 50% RH decreased when the w:cm ratio decreased. Tests conducted to investigate the effects of curing temperature and w:cm ratio on the setting time showed that CLSM sets faster as curing temperature increased from 50 degrees F (10 degrees C) to 90 degrees F (32.2 degrees C) w:cm ratio decreased from 1.0 to 0.8.