Performance of Superplasticizers in Alkaline Environment of Self Compacting Geopolymer Mortar

Abstract

Self-compacting geopolymer concrete (SCGC) is a revolutionary concept in the construction industry. This study fills the research gap by determining the impact of six different types of commercially available superplasticizers on the flow properties, dry density and compressive strength of SCGM. It was investigated that the relationship between relative flow area (Gm) and relative flow speed (Rm) of SCGM depends on the type of superplasticizer. The test results exhibited that a polyaryl ether-based superplasticizer performed better in increasing the flow deformability and flow speed of SCGM in comparison to melamine-based and naphthalene-based superplasticizers. The excessive increase in air content of SCGM paste with the addition of some superplasticizers had a negative impact on the flow properties. The increase in sodium oxide to silica molar ratio (Na2O/SiO2) and sodium oxide to water molar ratio (Na2O/H2O) both had a negative impact on the flow properties of SCGM. It was determined that beyond a trigger value of Na2O/SiO2 of 0.171, the impact of the superplasticizer in separating the flowing particles of SCGM became insignificant, resulting in the flash setting. Moreover, the addition of each type of superplasticizer had a negative impact on the dry density and compressive strength of SCGM.