Factors affecting the Characteristics of Self-Compacting Geopolymer Concrete

Abstract

The aim of this research was investigation the effect of sodium hydroxide (SH) concentration and the ratio of sodium silicate (SS) to sodium hydroxide (SS/SH) on the fresh and hardened characteristics of fly ash (FA) related self-compacting geopolymer concretes (SCGC) containing recycled coarse aggregate (RCA). In addition to the influence of both curing time and temperatures on the compressive strength of SCGC specimens was also evaluated. Therefore, SCGC mixes with various SS/SH ratios (1.5, 2.0, 2.5 and 3.0) and three varies SH concentrations (8M, 10M, and 12M) were designed. Six SCGC mixes containing 100% RCA were prepared. Both SH and SS solutions are used as alkaline activators. Fresh properties were evaluated according to the EFNARC specification. Although compressive strength was utilized to indicate the effect of the SH concentration and (SS/SH) ratio on the characteristics of SCGC specimens. The results of the experiments revealed that the ratio of SS/SH and the concentration of SH have a major influence on the efficiency of (SCGC). The optimum SS/SH ratio was 2.5. Furthermore, the research revealed that SCGC mixtures containing RCA conformed to the fresh properties limitations according to the EFNARC requirements for SCC. Moreover, the optimum oven curing time and temperature were 24 hr and 75 °C respectively.