Fracture toughness of plain concrete made of crushed granite aggregate

Abstract

An experimental investigation on the fracture toughness of plain concrete using the threepoint bending tests proposed by RILEM was carried out. A series of central-notched concrete beams made of local ingredients and with different concrete strength f cu and aggregate sizes (D max = 10 mm and D max = 20 mm) were tested. From the experimental results, the fracture parameters, namely the critical stress intensity factor KIC , the critical notch depth ac and the critical energy release rate G IC for the effective crack model and the fracture energy G F and the characteristic length lch for the fictitious model were determined and presented quantitatively. The experimental results indicate that K IC and G F increase as the compressive strength f cu increases for both aggregate sizes; at the same mix proportion and aggregate content, concrete with larger aggregates has a lower compressive strength f cu and elastic modulus E but a higher fracture resistance than that with smaller aggregates. Simple empirical formulae for the determination of fracture parameters were developed, providing a quantitative reference for the identification of the fracture parameters of normal and high-strength concrete with crushed granite aggregates.