Performance of a fly ash geopolymeric mortar for coating of ordinary portland cement concrete exposed to harsh chemical environments

摘要

Premature degradation of ordinary Portland cement (OPC) concrete infrastructures is acurrent and serious problem with overwhelming costs amounting to several trillion dollars. The useof concrete surface treatments with waterproofing materials to prevent the access of aggressivesubstances is an important way of enhancing concrete durability. The most common surfacetreatments use polymeric resins based on epoxy, silicone (siloxane), acrylics, polyurethanes orpolymethacrylate. However, epoxy resins have low resistance to ultraviolet radiation whilepolyurethanes are sensitive to high alkalinity environments. Geopolymers constitute a group ofmaterials with high resistance to chemical attack that could also be used for coating of concreteinfrastructures exposed to harsh chemical environments.This article presents results of an experimental investigation on the resistance to chemical attack (bysulfuric and nitric acid) of several materials: OPC concrete, high performance concrete (HPC),epoxy resin, acrylic painting and a fly ash based geopolymeric mortar. Three types of acids, eachwith high concentrations of 10%, 20% and 30%, were used to simulate long term degradation bychemical attack. The results show that the epoxy resin had the best resistance to chemical attack,irrespective of the acid type and acid concentration.