Rheological properties of rock-based geopolymer slurries with different dispersant and counterion combinations

Abstract

The production of Ordinary Portland Cement (OPC) is responsible for a significant part of global CO2 emissions. A potential alternative to OPC is alkali-activated materials (AAM), which do not contain OPC and are not produced in processes to release CO2. Thus, these materials have considerably lower CO2 emissions during production. It is estimated that the CO2 emissions from rock-based geopolymer concrete would be 70-80 % less than that of standard OPC based concrete. Furthermore, the use of mine tailings in concrete will reduce the area needed for landfills, thereby lowering the impact on natural resources. Dispersants, plasticizers or superplasticizers are important admixtures that increase the workability of fresh concrete, usually by lowering the yield stress or reducing the viscosity. The rheological properties of slurries with 7 different dispersants were tested in different ionic compositions. The dispersing effect seems to be highly dependent on the type of dispersant and the ionic composition of the slurry. Four different types of lignosulphonates were tested with varying dispersing effect in the different slurries. The chemical structure and its behaviour in the systems seems to be crucial for the dispersing effect.