Rehabilitation of Sewer Pipes and Related Infrastructure with Geopolymer and Alkali-activated mortar

Abstract

The concrete sewer pipe network, comprising approximately 122,000 km across Australia, is crucial for ensuring the livability and productivity of cities and communities. It was designed with an intended service life of around 100 years. However, these sewer assets face deterioration due to various factors, including microbial-induced concrete corrosion (MICC), which is the most aggressive threat. The MICC involves complex chemical and biological reactions, leading to the degradation of sewer assets in a short period. To mitigate MICC impact, several strategies focus on reducing hydrogen sulphide (H2S) through chemical dosing and surface protective coatings. However, these approaches pose long-term operational and financial challenges. Surface protective linings, particularly alkali-activated binders (AAB) like geopolymer, offer a promising alternative. Despite their promising qualities, these materials have not been utilised as protective linings in sewer asset applications for a few reasons. For example, there is a lack of corrosion resistance performance data and guidelines for their application and selection, especially in actual sewer environments. This study addresses these challenges by developing a framework to predict the service life and select criteria for AAB mortar under live sewer conditions using four commercially available geopolymer mortars (OGPm) and one calcium aluminate cement mortar (CACm). The results indicated three stages of corrosion steps, with CACm outperforming OGPm due to its composition, ANC, porosity, and UCS. The study presents service life prediction models for AAB mortar, incorporating sewer environment conditions, mortar properties, and time. This research marks the first instance of developing a service life prediction model considering real-world field applications, contributing valuable insights into the selection of protective lining materials for sewer asset rehabilitation.