Investigation of the Effect of Aggregate/Cement and Water/Cement Ratios on Concrete Workability

Abstract

Workability of fresh concrete is defined by its consistency, mobility, and compactability. Several factors influence concrete workability, but this study focuses on the effect of aggregate/cement (AG/CM) and water/cement (W/C) ratios. The objectives of the study are to determine the aggregate/cement and water/cement ratios of freshly prepared concretes; MC1, MC2, MC3, MC4, MC5 and MC6 of different mix ratios and their effect on concrete workability. Slump, Compacting factor, and modified vebe tests were performed under ambient conditions of 26-30\(^{\circ}\)C temperature, 92 percent relative humidity, and less wind to achieve this. The tests were carried out on fresh concretes of AG/CM ratios: 6.1, 5.0, 4.0, 3.0, 2.5, 2.1, and W/C ratios: 0.6, 0.55, 0.5, 0.45, 0.4 and 0.38. According to the findings, slump and compacting factors increase as the AG/CM and W/C ratios decrease, implying that as workability increases, the AG/CM and W/C ratios decrease as well. The results also showed that the Vebe time increases as the AG/CM and W/C ratios increase, which means that it is less difficult to vibrate concretes of low AG/CM (\(\le\)3.0) and W/C (\(\le\)0.45) ratios. Again, the AG/CM ratio rises as the W/C ratio rises. Regression analysis carried out also showed that the regression coefficients (R²) obtained from Slump-AG/CM, Slump-W/C, Compacting factor-AG/CM, Compacting factor-W/C, Vebe time-AG/CM, and Vebe time-W/C curves are 96.7%, 98.8%, 99.4%, 99.3%, 99.1%, 99.4% indicating a clear relationship with each other.