Effect of biochemical attack on the mechanical performance of used concrete sewer pipes

The structural response and failure mechanisms of 35 used concrete sewer pipes are investigated by means a combined experimental–numerical approach, whereby specific attention focuses on determining the effect biochemical attack. Accordingly, degree degradation inner outer surfaces is carefully analysed visual inspection, subsequently categorized in 6 different surface condition classes. type attack determined respectively performing X-ray diffraction analyses phenolphthalein tests. pipes, which vary age, size geometry, subjected to biaxial loading conditions full-scale test set-up. experiments show that material relatively old can be considerable, for large part may attributed process biogenic sulphide corrosion. This typically induces weak, corroded layer at inside pipe, characterized appearance exposed granulates porous mortar between granulates. experimental responses compared against numerical results obtained from detailed Finite Element Method (FEM) simulations. each pipe well predicted FEM model if negligible mechanical properties corrosion accounted low tensile strength reduced effective wall thickness due cause ultimate bearing stiffness these more than factor two lower those completely new pipes. present work provide scientific basis decision-making rehabilitation replacement, particular revealing quantifying influence