Study on fracture properties of alkali-activated slag seawater coral aggregate concrete

Abstract

Alkali-activated slag was first used as cementing material in seawater coral aggregate concrete (SCAC) production in this paper. It would contribute to both the environmental protection and raw materials obtained locally in island construction far away from the mainland. However, cracks would be harmful to structural durability of SCAC especially under ocean environment. Thus, the present study is mainly aimed at the fracture properties of alkali-activated slag SCAC (ASSCAC) by virtue of three-point-bending tests. Two types of slag (Types A and B) and two types of coral aggregates, namely columnar and crushed coral coarse aggregates (CCA), are considered. Besides, two beam depths of 100 mm and 150 mm are prepared and the initial notch-to-depth ratios are set from 0.1 to 0.7 for each depth. Results show that the failure modes of all the beams are fracturing of CCAs. Then an analytical approach was proposed to predict the fracture parameters of ASSCAC. The size-independent uniaxial tensile strength and fracture toughness are obtained by using the experimental maximum fracture loads and the former proves to be the maximum tensile stress at the fictitious crack-tip. Then the correlation between the maximum fracture load and the local fracture energy at crack-tip region is obtained. The size-independent fracture energy is derived based on the comparison between the analytical and experimental maximum fracture loads. The tensile strengths of ASSCAC mixed by Type A slag and crushed CCAs are larger. But the fracture toughness and fracture energy are slightly higher when the ASSCAC is made by Type B slag.