Effect of early-age freeze-thaw exposure on the mechanical performance of self-compacting repair mortars

Self-compacting repair mortar (SCRM) is a functional material for repair or retrofit applications. Industrial byproducts, such as fly ash (FA) or ground granulated blast furnace slag (GGBFS), can be used to reduce cement dosage and to obtain an eco-friendly material. However, these waste materials may cause durability problems at early ages as a result of curing sensitivity. In this study, the effects of high-volume FA and GGBFS replacement on early-age freeze-thaw (F-T) resistance of SCRM with and without steel microfibers were investigated. The mechanical properties, including fracture energy, were determined after F-T cycles. The fresh state properties and volume stability of the hardened specimens were studied. The results demonstrated that prolonged curing is essential to avoid the loss in mechanical properties due to F-T exposure. SCRM containing high-volume byproducts seem vulnerable to the effect of F-T at early ages, and this negative effect cannot be overcome with steel microfibers.