MECHANICAL PROPERTIES OF SELF-COMPACTING CONCRETE WITH RECYCLED CONCRETE AGGREGATE, FLY ASH AND GRANULATED BLAST FURNACE SLAG

Abstract

In recent years, the demand for construction materials has grown tremendously, likewise the
amount of construction and demolition waste, putting huge pressure on the environment. This has encouraged the use of recycled aggregate in concrete. This research aims to evaluate the mechanical properties of Self-Compacting Concrete with Recycled Concrete Aggregate (RCA) in varying percentages of replacement for Natural Coarse Aggregate (NCA). A total of 20 concrete mixtures were prepared and tested. Mixtures were divided into five different groups, with different volume fractions of Recycled Concrete Aggregate of 0%, 25%, 50%, 75% and 100% of NCA. The concrete is designed for a water-cement ratio of 0.38. Mixtures were designed with 50% of Portland cement substituted by a combination of class C fly ash and granulated blast furnace slag. The evaluation of concrete properties will include the workability of concrete using a slump test, compressive strength, and splitting tensile strength at the ages of 3, 14, and 28 days of curing. The results indicate that replacing the coarse aggregate with high percentages of RCA reduces the workability of the SCC. The addition of 25% FA + 25% SL in place of Portland cement increases the magnitude of the slump flow. The 28-day compressive strength of SCC with 50% SL is 5.3% less than the control. The inclusion of slag had a minimal effect on the 3, 14, and 28-day compressive strength. The optimum Recycled Concrete Aggregate content of 50% shall be used in SelfCompacting Concrete based on the findings of the results.