Surface Preparation to Promote Adhesion of Protective Cement Mortars on Corroded Sewer Assets

Abstract

This work evaluated the concrete substrate requirements to promote the adhesion of protective mortars, specifically calcium aluminate cement (CAC) and one-part geopolymer (GP) mortars. Adhesion tests were performed by direct application on corroding OPC sewer assets that have been in service for 18-81 years. Adhesion tests revealed the effect of factors including cleaning method and type of coatings on the interfacial microstructure, cement chemistry, surface pH and surface roughness and their subsequent impact on bond strength development with time. The outcomes of this study provide preliminary guidelines for surface preparation to optimise mortar adhesion, including the methods of removing corroded materials, the amount of unsound materials that need to be removed and test methods to determine when sound concrete has been achieved to qualify the surface preparation.