Long-term volume stability of ECC containing high-volume steel slag

Abstract

The utilization of steel slag (SS) in the field of concrete remains limited due to its poor soundness. This work studies the long-term volume stability and strength development (up to 1 year) of engineered cementitious composites (ECC) containing high-volume SS. The result shows that the compressive, splitting-tensile and flexural strength of ECC containing SS begins to decline after 90 d, while the decline in the corresponding matrix is much higher. Especially, the matrix with 60 wt% SS loses its integrity by 360 d. The expansion of SS reduces the fracture toughness of the matrix, leading to an increase in toughness and ductility, while changing the cracking pattern of the ECC. Additionally, the introduction of ground granulated blast furnace slag (GGBFS) results in a decrease in volume expansion and strength loss of ECC caused by expansion of SS. Randomly distributed PVA fibers restrict volume expansion of ECC containing SS, while trapped air pores introduced with PVA fibers act as relievers, dispersing expansive stress. Combined introduction of GGBFS and PVA fibers leads to a 49.8 % reduction in expansive strain and a 126 % increase in compressive strength of ECC compared with the matrix with high-volume SS.