Experimental study of sustainable recycled concrete aggregates in steel-concrete composite construction

The use of recycled concrete aggregates is a sustainable alternative for natural aggregates. It reduces concrete waste produced in construction and demolition. Since there has been limited research on the use of recycled concrete aggregates in steel-concrete composite construction and various standards such as Australian Standard AS 2327.1 [1] and Eurocode 4 [2] do not provide specifications for the use of recycled concrete aggregates in composite steel-concrete construction. Therefore, this paper investigates the integration of recycled concrete using sustainable recycled concrete aggregates in composite steel-concrete beam structure. This paper presents an experimental study on the ultimate load behaviour of composite steel-concrete beams. A total of fifteen composite steel-concrete beams with different concrete mix comprised of various percentage of recycled aggregates (0%, 30%, 50%, 70% and 100%) and water to cement content ratio (0.35, 0.45 and 0.55) were tested. Each beam was simply supported at the ends and was subjected to applied load at mid-span. From the experimental study, it was found that the 0.35 and 0.45 water to cement ratio achieved higher ultimate load capacity than 0.55. The optimal replacement percentage of recycled concrete aggregates was 70% with the highest ultimate load capacity. Furthermore, there was no significant reduction in strength when recycled concrete aggregate was used to replace the natural aggregate in the concrete mix for composite steel-concrete beams.