Djwantoro Hardjito

ON THE DEVELOPMENT OF FLY ASH-BASED GEOPOLYMER CONCRETE

The contribution of ordinary Portland cement (OPC) production worldwide to greenhouse gas emissions is estimated to be approximately 7 percent of the total greenhouse gas emissions to the earths atmosphere. To reduce greenhouse gas emissions, efforts are needed to develop environmentally friendly construction materials. This article presents the technology of making geopolymer concrete using low-calcium dry fly ash as its source material; the authors present the results of laboratory tests conducted on this material. Results show that higher concentration of sodium hydroxide solution results in a higher compressive strength of geopolymer concrete; as the curing temperature in the range of 30 to 90 degrees C increases, the compressive strength of geopolymer concrete also increases; longer curing time (in the range of 6 to 96 hours) produces larger compressive strength of geopolymer concrete; the addition of high-range water-reducing admixture, up to approximately 2 percent of fly ash by mass, improved the workability of fresh geopolymer concrete with very little effect on the compressive strength of the hardened concrete; the geopolymer concrete undergoes very little drying shrinkage and low creep. The authors conclude by discussing the application of geopolymer concrete and future research needs.

Fly Ash-Based Geopolymer Concrete

Abstract In recent years, attempts to increase the utilisation of fly ash to partially replace the use of Portland cement in concrete are gathering momentum. Geopolymer concrete is a ‘new’ material that does not need the presence of Portland cement as a binder. Instead, activating the source materials such as fly ash that are rich in Silicon (Si) and Aluminium (Al) using high alkaline liquids produces the binder required to manufacture the concrete. Hence, concrete with no cement. This paper presents information on fly ash-based geopolymer concrete. The paper covers the material and the mixture proportions, the manufacturing process, and the influence of various parameters on the properties of fresh and hardened concrete.