Mechanical Properties of Fly Ash and Ferrochrome Ash-Based Geopolymer Concrete Using Recycled Aggregate

Recycled aggregate (RCA) is a term which is used to describe crushed concrete or asphalt from construction debris, which is also used to make other building projects. This method of construction is generally used for making road base or other different infrastructure-based projects. The source of RCA is nothing but the local construction and demolition waste in KIIT Deemed to be University, Bhubaneswar, Odisha. This paper suggests the experimental results and analysis to study the behaviour and feasibility of the use of RCA in concrete form as a replacement of natural coarse aggregate. In this research work, fly ash and ferrochrome ash-based geopolymer concrete are used, and 13 M concentration of caustic soda (NaOH) and sodium silicate (Na₂SiO₃) alkali activators are utilized to synthesize the fly ash and ferrochrome-based geopolymer concrete. Alkali activators to fly ash ratio are constant for all series. Experimental result shows that the strength of geopolymer concrete decrease with an increase in RCA contents up to 50%. Though recycled aggregates, fly ash and ferrochrome ash are waste materials used for making geopolymer concrete, experimental results revealed that up to 20% of replacement of recycled aggregate can achieve the strength and it can be the recommended percentage of RCA in concrete industry.