The Use of Metakaolin and Geopolymer Cement to Improve Concrete Resistance to Sulfuric Acid Attack

Abstract

Corrosion of concrete sewer pipes by sulfuric acid attack is a problem of global scope. The current paper aims at evaluating two supplementary cementing materials metakaolin and geopolymer cement as partial cement replacements for improving the ability of concrete to resist severe sulfuric acid attack. Both, metakaolin and geopolymer cement were found to significantly improve the resistance of concrete made to Type 10 and 50E cements to 3% and 7% sulfuric acid solutions (pH of 0.6 and 0.3, respectively). Maximum weight loss reduction with respect to the control for specimens made of modified Type 50E cement ranged between 20 and 37%, depending on the additive and the concentration of the acid. Maximum weight loss reduction for specimens made of modified Type 10 cement range between 10 and 42%, depending on the additive and the concentration of the acid. For this test Type 10 cement was found to perform best in the presence of geopolymer cement while the performance of the Type 50E cement was best when metakolin was used as partial replacement for cement. The results emphasize the important role that the nature and composition of hydration products and the completeness of the hydration process play in improving concrete resistance to acid attack.