THE EFFECT OF CONCRETE STRENGTH ON CRACK PATTERNS

It is well known that the cracks that develop in concrete as it is loaded to failure are affected by the aggregate particles, particularly by the coarse aggregate. Because of the very different fracture energies of the hydrated cement matrix and the aggregate particles, the details of the crack path are important in determining the fracture energy of the composite. It is commonly assumed that, for normal mortars or concretes, cracks tend to go around aggregate particles. For high strength concrete, some cracks will go through the aggregate particles, though the more common crack path will still be around the aggregate. The purpose of the present study was to compare the crack patterns that developed in different types of plain concrete using specimens in which the stresses of the crack tip were primarily tensile. In addition, the effect of loading rate on the crack pattern was also studied.