Effect of Exposure of Cement on the Compressive Strength of Concrete

Abstract

Concrete quality is of paramount importance to engineers and this is dependent on the quality of cement. One of the reasons for poor quality of cement is exposure condition of cement which is considered in this research. The behavior of the compressive strength of concrete with respect to the duration of exposure of cement was investigated and the limiting duration of exposure of cement beyond which it is not fit for structural concrete was established. Two basic exposure conditions were considered (Warehouse and Open-Air) for different durations (ranging from 6 to 42 hours). The target strength of concrete for this research was 30MPa; Slump and crushing tests were carried out for 99 samples and it was observed that the strength of concrete significantly reduced from 29.13MPa for the control sample (No exposure) to 17.28MPa and 13.90MPa for 42 hours cement exposure under Warehouse and Open-Air exposure respectively. A regression model was calibrated to predict the strength of concrete and % Loss of strength with increase in exposure duration for both conditions, this model possessed high correlation. Furthermore, the limiting exposure duration was established to be 16.7 hours and 10.5 hours under Warehouse and Open-Air exposure respectively. Finally, it was observed that the Strength of concrete is hugely dependent on the quality of cement which is significantly affected by the exposure duration; also, the workability of the concrete is not affected by the exposure of cement.