Effect of Cement to Aggregate Ratio and Compaction Effort on Properties of Pervious Concrete Made of Ternary-Sized Gravel

Abstract

This research work investigates the effect of the cement to aggregate ratio (c/a) and the effect of compaction effort on properties of pervious concrete made of ternary-sized river gravel. The ternarysized gravel used in the experiment was a mix of the three most abundant particle sizes presented in natural gravel (1/2”, 3/8”, and No.4), with a mass composition of 50:25:25. Three concrete mixtures with different c/a ratios of 1:7, 1:8, and 1:9 (by weight) were produced using the same water to cement ratio of 0.3. The compaction effort applied for each concrete mixture was varied by dropping a standard compaction hammer either at 15, 20, or 25 blows/layer. The properties of the pervious concrete obtained in this study included the effective void content, the unit weight, the compressive strength, and the permeability coefficient. Experimental results showed that the pervious concrete made of this gravel exhibited the compressive strength ranging from 8.06–13.73 MPa, and the permeability coefficient varying from 1.13–1.82 cm/s. The results also showed that properties of the pervious concrete are strongly influenced by the cement to aggregate (c/a) ratio and the compaction effort. Increasing aggregate ratio resulted in enhancing effective void content and permeability coefficient, thus lowering the compressive strength and the unit weight of the concrete. In contrast, an increase in compaction effort resulted in a decreased effective void content and a reduced permeability coefficient, leading to an improved compressive strength and an increased unit weight of the concrete. It was also found that the unit weight, the compressive strength, and the permeability coefficient are linearly correlated with the effective void content of the hardened concrete.