The effect of aggregate-to-cement ratio and types of aggregates on the properties of pre-cast concrete blocks

The effects of aggregate-to-cement (A/C) ratios and types of aggregates on the properties of pre-cast concrete blocks are evaluated in this study. A/C ratios between three and six and three types of aggregates (i.e., natural crushed aggregate (NCA), recycled crushed aggregate (RCA) and recycled crushed glass (RCG)) were used in the experiments. It was found that the compressive strength of the paving blocks decreased as the A/C ratio increased. The results showed that the strength was directly proportional to the crushing strength of the aggregates (i.e., 10% fines value). Moreover, the water absorption of the blocks had a good correlation with the water absorption ability of the aggregate particles. The use of RCA as a replacement of NCA in the production of concrete blocks reduced the density and strength but increased the water absorption of the blocks. However, the potential high water absorption of the blocks as a result of the incorporation of RCA could be ameliorated by the use of RCG since RCG particles had a low water absorption value.