: Effects of Slag Substitution on the Properties of Self-Consolidating Concrete including Recycled Coarse Aggregates

In this study, the feasibility of the use of slag from blast furnaces as an alternative to a percentage of cement and recycled coarse aggregate and simultaneously as a substitute for natural coarse aggregate was investigated, both of which are secondary and waste products and are fine for the construction of self-consolidating concrete blends. For this purpose, mixtures with 0, 15%, and 25% of slag volume replaced cement, and mixtures with 25%, 50%, 75%, and 100% of recycled coarse aggregate replaced natural coarse aggregate in the 15 mix design with a water-cement ratio 48%. For characterizing the mechanical properties of recycled self-consolidating concrete containing slag flexural strength testing at ages 7, 28, and 91 days were measured. Furthermore, to determine the rheological properties of self-consolidating concrete slump flow and J ring tests were used. The water absorption tests were also used as an indicator of permeability and durability of concrete at ages 2, 3, 7, and 28 days and the tensile strength test was also conducted at 28 days. The results show that the compressive strength of slag samples containing 7-day aged was a little, but gradually after a while reasonable strength was achieved at age of 28 and 91 days. The best result of this study showed that cement replacement by 15 percent of slag and natural coarse aggregate replacement by 25 percent of recycled coarse aggregate, in terms of compressive strength, tensile strength, water absorption and rheological properties of self-consolidating concrete permissible and acceptable results were obtained.