Evaluation of key aggregate parameters on the properties of ordinary and high strength concretes

This paper reports the results of a study conducted to determine the influence of coarse aggregate type on the workability, compressive strength, and flexural strength of normal and high strength concretes with target 28-day compressive strengths of 30 and 60 MPa and two water/cement ratios of 0.44 and 0.27. The concretes were prepared using four types of natural coarse aggregates, namely diabase, calcareous, river gravel, and basalt, with maximum particle sizes of 12.7 and 19.1 millimeters. Silica fume was added to the high-strength concretes at a replacement ratio to Portland cement of 10% by mass. The results showed that among all aggregates, basaltic aggregate with a maximum particle size of 12.7 millimeters produced concrete with the highest compressive and flexural strength, followed by limestone and river aggregate, indicating that particle size, surface texture, structure and mineralogical composition play a dominant role in the behavior of concretes, especially high strength concretes. Normal strength concretes showed similar compressive strengths, while the concrete containing limestone gave slightly higher strength. These results show that for a given water/cementitious material ratio, the influence of the type of coarse aggregate on the compressive strength of the concrete is more important for high strength concrete than for normal strength concrete.