Published Online: 3 August 2005
Page Count: 14
(Received 14 March 2005; accepted 28 June 2005)
A high stress causes development of cracks, which may fracture aggregate particles or skirt around them. Numerous factors influence the path taken by a crack. No direct studies are available, but the relevant factors are: properties of the parent rock; shape, size, and texture of coarse aggregate particles; properties of the interface and bond; moduli of elasticity of the aggregate and of the matrix; and strength of the matrix relative to the strength of the aggregate. At very early ages, fracture parameters change, but later on, age is not a factor influencing the crack path. The crack path influences the shear strength of beams, in that cracks passing through the aggregate reduce the contribution of aggregate interlock: some aggregates result, therefore, in a low shear strength. This has been found only recently. Establishing experimentally the influences on the crack path would enable us to design mixes economically with balanced properties of strength and ductility.
Paper ID: JAI14092