Durability Performance of Fly Ash Based One-Part Geopolymer Mortars

Environmental concerns regarding the high CO2 emissions related to the production of ordinary Portland cement (OPC) led to research efforts on the development of eco-efficient alternative binders. Geopolymers constitute promising inorganic binders alternative to OPC which are based on aluminosilicates by-products and alkali activators. The geopolymerization technology of aluminosilicates 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 first proposed in 2007. However, very few papers were published on these materials. This paper presents experimental results on the durability performance of one-part geopolymers concerning water absorption, penetration of chloride, carbonation resistance and resistance to acid attack. Hydration products results assessed by FTIR spectra are also presented.