Abstract
The author reports on the compreseive strength of concrete with particular reference on size and quantity of artificial lightweight aggregate. Several series of tests are carried out using one size aggregate which are in narrow range of size. The concretes had shown breaking of aggregate particle before the maximum stress were reached, as well as bond failure in the interface. In this point expanded shale aggregate concretes are different from river gravel concrete. It is shown, however, that the larger is the particle and the more aggregate is contained in concrete, the weaker is the concrete. This means that the strength of one size aggregate concrete is expressed as a plane in a space co-ordinates with the strength and aggregate size and quantity as its axis, as in gravel concrete. It is therefore possible to presents an interpretation that the ordinary (mixed size aggregate) concrete has its own strength composition according to the volume and the size of artificial light weight aggregate.
