Development Of Geopolymer Concrete For Precast Structures

Abstract

This study presents 'geopolymer' as a new binder to replace Portland cement in concrete to make concrete more environmentally friendly and durable. This utilizes industrial by-products like fly ash which is disposed in landfills. Therefore, the use of geopolymer as a binder in concrete production not only reduces the emission of CO2 because of elimination of cement, but also utilizes an industrial by-product to produce a green and sustainable construction material. In this research, the fly ash and alkaline liquid (mix of sodium hydroxide and sodium silicate) were used as the basic constituents of the geopolymer. More than 1000 cylinders were prepared using different mix designs and tested in accordance to American Standard Testing and Material (ASTM) C39 for comparing compressive strength. Geopolymer and reinforced concrete pipes were produced, tested according to ASTM C497, and compared in terms of crack pattern. In addition, factors such as molarity of sodium hydroxide, size and amount of aggregates, curing temperature, curing method and time, types of fly ash and addition of crumb rubber or steel fibers that influence the compressive strength were studied. The result showed that the mix design prepared with 9.42% CaO fly ash of 14M cured at 24hrs./158°F/oven containing amounts of larger sized aggregates produced the maximum compressive strength.