Effect of ground granulated blast furnace slag on cement hydration and autogenous healing of concrete

Concrete is an open composite system, which allows the incorporation of various cementitious or inert materials as cement or aggregate components, thereby offering the possibility of creating a smart concrete. This study investigated the autogenous healing of concrete blended with ground granulated blast furnace slag (GGBS) and polyvinyl alcohol (PVA) fiber in terms of flexural strength recovery and crack sealing behavior. It was found that 50% GGBS-blended concrete showed good autogenous healing ability and the addition of PVA fibers indirectly further increased the effectiveness of autogenous healing in concrete. The hydration of cement paste was investigated for its relationship with autogenous healing using isothermal calorimetry, X-ray diffraction (XRD), and thermogravimetric analysis (TGA). The exterior of GGBS-blended concrete was prone to carbonation which could affect its autogenous ability. The hydration rate and ultimate degree of hydration of GGBS-blended concrete were lower than those of pure Portland cement concrete, suggesting that the use of GGBS provides a greater potential for autogenous healing both in the short and long term.