Abstract
It has been reported previously by the author that at a given mortar the larger is the size and the greater the volume fraction of gravel, the lower is the compressive strength in one size gravel concrete. And an interpretation was presented that the strengh of one size gravel concrete can be represented in a plane defined by the size and the volume fraction of gravel. The present report discusses the character of the strength plane with reference on consistency of concrete. The volume fractions of gravel in concrete and of sand in mortar are taken up as the factors influencing the consistency of concrete. It is shown that the concrete strength of the same consistency is represented as a line on the strength plane when the consistency is ajusted by the size and the volume fraction of gravel and that the strength plane can be assumed to be constructed with these lines. Test result shows that the larger is the sand content in mortar, the smaller is the strength deduction of concrete from the mortar strength and the value of strength deduction is the same at any water cement ratio when mix proportion of cement paste, sand and gravel is kept the same. Thus the sand content in mortar is thought to play important role in strength of concrete as well as water cement ratio, the size and volume fraction of gravel.
