Experimental study of the effect of silica fume and coarse aggregate type on the fracture characteristics of high-strength concrete

This research investigated the fracture properties of high-strength concrete (HSC) using different amounts of silica fume (SF) and coarse aggregate (CA) types and a total of 10 mixing designs and 150 beams. Mix design for plain HSC without SF and three mix designs for SF having contents of 5%, 10%, and 15% by weight of cementitious materials were prepared to evaluate the fracture characteristics in two ratios of water to binder (w/b) of 0.24 and 0.35. In addition, three types of crushed CA, including Limestone, Andesite, and Quartzite were examined to study the effect of CA type on the fracture behavior. The laboratory examination was performed using work of fracture method (WFM) and size effect method (SEM). The results showed that by increasing the amount of SF in two w/b ratios, initial fracture energy (Gf), total fracture energy (GF), characteristic length (Lch), and effective length of fracture process zone (Cf) were decreased, but brittleness number (beta) was increased. Furthermore, the CA types significantly affected the fracture and mechanical parameters, and Quartzite and Andesite CA enhanced the fracture energy and the characteristic length compared to Limestone CA.