Decision Framework for Polymer Composite Linings in Trenchless Renewal: Integrating Materials Durability, Operational Performance, Application Quality, and Environmental Sustainability

Polymer composite linings are increasingly used in trenchless renewal technologies. These technologies are advantageous when material durability, structural requirements, application quality and service exposure are considered together, yet renewal decisions are still made largely case by case, often overlooking some of these aspects. This paper develops an evidence-based decision framework in which every decision rule is an explicit, traceable statement linked to measured or published evidence. The evidence base integrates long-term hygrothermal ageing of reinforced polyester and elastomer-modified epoxy linings, linings removed from service after up to ten years, measured application quality, cure kinetics, material identity verification and environmental assessment. Screening flowcharts decide whether to renew, repair or replace and which lining system or polymer composite is technically suitable; an evidence matrix then compares the remaining options with stated evidence levels; and a staged quality assurance and quality control protocol, linked to a defect–cause–control table, makes application quality verifiable. Three asset archetypes demonstrate how it routes decisions and what records each decision must leave.