Effects of Curing Conditions on Strength Development of Controlled Low-Strength Material

Abstract

This research investigated the effects of a curing regime on the compressive and splitting tensile strength of controlled low-strength material (CLSM). Six CLSM mixtures representing a range of materials and mixture proportions were included in the study. Three curing temperatures were used, and for each curing temperature, 2 different relative humidity conditions were used to examine the influence of temperature and humidity on strength gain at ages of 7, 28, and 91 days. The effects of temperature and humidity were found to largely depend on the constituent materials and mixture proportioning. In particular, reactivity of fly ash was found to be critical in influencing the strength of CLSM mixtures, especially when an ASTM Class C fly ash was used. Some CLSM mixtures containing Class C fly ash exhibited a significant increase in strength when cured under the highest temperature conditions. Although the dependence of cementitious materials containing fly ash on temperature is well known, the increases in strength of CLSM mixtures containing a high-calcium fly ash far exceeded the strength increases typically observed for conventional concrete.