Application of the size effect on the compressive strength of the concrete is studied. The concrete specimen in compression fails due to lateral tensile strain, and the cracking produced by lateral tensile strain can be assumed to propagate with a dispersed zone of microcracks in a compressive failure. The size effect is not recognized statistical strength, but derived from the fracture mechanics. The theory is based on the fact that a highly unstable equilibrium exists between the respective rates of strain-energy release and energy demand.
The size effect law derived by Z.P.Bazant is used, which was derived from NLEFM(Non-Linear Elastic Fracture Mechanics) for the microcrack zone of the macrocrack tip. Theoretical studies based on the concept of the fracture mechanics are reviewed and discussed.
This paper presents a model of the size effect on the compressive strength in concrete by our test data and the existing data in references for the cylinder and the cube with varing in the specimen size and the maximum aggregate size.
Experimental evidence is presented that the smaller specimens for the cylinder and the cube indicate the higher strength, i.e, size effect.
