Experimental investigation on the effect of coarse aggregate size and silica fume dosage to the fracture parameters of concrete

Two-parameter model proposed by RILEM was applied to determine the critical stress intensity factorand critical crack tip opening displacement (CTODc) of concrete with different coarse aggregate sizes and silica fume dosages. The characteristic length 1,h was used to evaluate the effects of coarse aggregate size and silica fume dosage on the brittleness of concrete. All specimens were tested at 28 days. The test results show that for normal strength concrete NSC1 and NSC2, the compressive strength, splitting tensile strength, elastic modulus and critical stress intensity factor of NSC1 (with coarse aggregate size 6.7 similar to 10mm) is higher than NSC2 (with coarse aggregate size 2.36 similar to 6.7mm), NSC2 behaves more brittle than NSC1. The situation is on the opposite for high strength concrete HSC1 and HSC2. The compressive strength, splitting tensile strength, elastic modulus and critical stress intensity factor of MSC2 (containing 10% silica fume) is higher than MSC1 (without silica fume), but MSC2 is more brittle than MSC1.