Fracture parameters of site-cast dam and sieved concrete

Abstract

A conversion relationship between the fracture parameters of site-cast dam concrete and that of sieved concrete is presented. The concrete mixture produced by the mixing tower system on the construction site of a super-high arch dam was used to cast and mould different sized specimens. The maximum aggregate size for the dam concrete specimens was 150 mm and that for the sieved concrete specimens was 40 mm. The fracture parameters of the dam concrete and sieved concrete, including fracture energy, effective fracture toughness, critical crack tip opening displacement and characteristic length, were determined. In addition, the effect of dam concrete and sieved concrete specimen size on fracture behaviour was analysed. It was found, regardless of the dam concrete or sieved concrete specimen, that when the ratio of the ligament height to the maximum aggregate size was equal to or greater than 6·0, stable values of the fracture parameters were obtained. Based on the test results, formulae for calculating the fracture parameters for large dam-concrete specimens were derived from those for small sieved-concrete specimens.