In-Plane Modes of Fracture and Effective Parameters of Self-Consolidating Concrete

Abstract

In this paper, Mode I and Mode II fracture energies of self-consolidating concrete (SCC) are examined. Two shapes of Mode II specimens are used, and the specimens are made from mixtures with three different water-to-cement (w/c) ratios. To determine the fracture energy, the size effect methodology is also considered. Results indicated a mixed-mode fracture for beam-type double-notched specimens under four-point loading. There is an evident size effect for the Mode II fracture that is pronounced for larger specimens. With the decrease in w/c ratio from 0.65 to 0.45, and thus increase in compressive strength from 26.44 to 53.5 MPa, the Mode II fracture energy increased by 47%. The brittleness number increased for specimens with higher compressive strength or larger size. The failure cracks propagate through the aggregates rather than the paste for lower w/c ratios. The Mode II fracture energy was on average 26 times the Mode I fracture energy, and this ratio grows by reducing the w/c ratio. Approximate empirical relations are proposed for Mode II fracture energy as well as the ratio of Mode II to Mode I fracture energy (GII/GI) in terms of the compressive strength. Mode II fracture energy takes a lower value for SCC compared with conventional concrete.