Fly Ash Based Geopolymer Concrete with Recycled Concrete Aggregate

Abstract

Concrete is one of the most consumed resources in the world. With an increased global focus on environmental concerns such as global warming, sustainable development and recycling; alternatives to conventional concrete are being researched, such as geopolymer concrete. Geopolymer concrete replaces cement based binder with an alternative binder which contains no Portland cement. One type of geopolymer binder is that which contains fly-ash activated by an alkaline solution of sodium silicate and sodium hydroxide. Utilising recycled concrete waste from construction and demolition sites, that would otherwise be disposed of into landfill, as a source of aggregate offers a potential environmental and economic benefit. The term recycled concrete aggregate (RCA) is used to define aggregate produced from crushed demolition and construction waste.Used together, geopolymer concrete and recycled concrete aggregate eliminate the need for Portland cement and makes use of waste materials. Significant research has been conducted into both recycled concrete aggregate (RCA) ordinary Portland cement concrete and geopolymer concrete; however there was limited published data on using RCA in geopolymer at the time of this research. Thus the aim was to investigate the mechanical properties of geopolymer concrete with recycled concrete aggregate as partial replacement of the natural coarse aggregate. This paper reports on the outcomes of the research which indicate the potential of incorporating RCA in geopolymer concrete mixtures.