Effects of Size and Volumetric Content of Coarse Aggregate on Compressive Strength of Concrete

The author reports hereunder on the compressive strength of concrete with particular reference on size and volume fraction of coarse aggregate. The aggregates used were glass marble, river gravel, crushed stone and expanded shale. Concrete with expanded shale has distinctive aspects in failure mechanism. It is shown, however, that in all cases the larger is the aggregate size and the more aggregate is contained in the concrete, the lower is concrete strength, and that the strength of single-sized aggregate concrete is expressed as a plane in a space co-ordinates with the strength and aggregate size and volume fraction of coarse aggregate as its axis. The author extends the rule to the ordinary concrete and presents an interpretation that concrete has its own strength composition according to the volumetric distribution of size of coarse aggregate.