A mix design procedure for low calcium alkali activated fly ash-based concretes

This paper presents a systematic approach for selecting mix proportions for alkali activated fly ash-based geopolymer concrete (GPC). The proposed mix design process is developed for low calcium Class F fly ash activated geopolymers using sodium silicates and sodium hydroxide as activator solutions. A review of the literature reveals that there are no published comprehensive approaches in designing mixes for GPC. In this paper the key factors that determine the characteristics of GPC mix are identified. The authors consider the water to geopolymer solid (W/GPS) and alkaline liquid to fly ash (AL/FA) ratios as direct measures of strength and workability. The ratio of alkaline liquid to water (AL/W) is identified to be most closely linked to the strength of GPC mixes. The paper presents detailed examples of mix designs for various strengths. (c) 2015 Elsevier Ltd. All rights reserved.