Durability of Geopolymer Concrete Subjected to Aggressive Environmental Conditions

Abstract

Cement production has a negative effect on the environment. Geopolymer technology offers an opportunity to obtain an environmentally friendly binder for the concrete. The use of geopolymer as binders may reduce the carbon dioxide emissions caused by the cement industry by about 80%. The most promising advantages of the geopolymer concrete are: lower harmful emissions, converting a variety of wastes into useful by-products, higher resistance to corrosion and fire, higher compressive and tensile strengths and improved durability properties. This research presents an experimental investigation done on the performance of geopolymer concrete subjected to severe environmental conditions. Five geopolymer concrete mixes and one conventional OPC concrete mix were investigated. The source materials for geopolymer concrete mixes were Fly ash (FA), metakaolin (MK) and ground granulated blast furnace slag (GGBFS). All mixes were labelled by the type and percentage of the source material, like S60% F40%, S80% F20%, S60% M40%, S80% M20%, S100%. The alkaline solution used for the present study is the combination of sodium silicate and sodium hydroxide solution with the ratio of 3.50. The test specimens were 10x10x10 mm cubes, 100 × 200 mm cylinders. After casting, the geopolymer concrete samples were cured at the ambient condition of the laboratory (15-20⁰C and 60±10% RH) until the test and the OPC concrete samples were cured under water for up to 28 days. The mechanical properties of the concrete were investigated by compressive strength and weight loss. The investigated durability properties were rapid chloride penetration, sorptivity, volume of permeable voids (VPV) and effects of the exposure to different aggressive environments. Durability of specimens were assessed by immersing the geopolymer concrete (GPC specimens in 25% sulfuric acid and 30% nitric acid solutions), periodically monitoring surface deterioration, changes in weight and strength over a period of 42 days.