Performance of fly ash based one-part geopolymer mortars in durability tests

Abstract

Environmental concerns regarding the production of cement particles in terms of energy consumption and CO2 emission resulted in to conduct widely studies for more environmentally viable alternatives. One of these alternative solutions is to use alkali-activated binder which is produced using industrial by-products containing silicate materials. Geopolymeric binders are the latest types of inorganic binders which use alkaline activation of wastes such as slag or fly ash. The geopolymerization of alumina-silicate materials is a complex chemical process evolving dissolution of raw materials, transportation, orientation and polycondensation of the reaction products. Classical two part geopolymers could become more eco-efficient with a lower CO2 footprint if sodium silicate usage is avoided. Besides current geopolymeric mixes can suffer from efflorescence originated by the fact that alkaline or soluble silicates that are added during processing cannot be totally consumed during geopolymerisation. Therefore, new and improved geopolymer mixes are needed. One-part geopolymers (sodium silicate free) were proposed in 2008. Up to now a lot of issues remain unexplained about them. Thus this study was assigned to investigate the durability performance of one-part geopolymers. The tests made comprise water absorption, penetration of chloride, carbonation, acid attack.