Water and sewer manholes are prone to chemical degradation, resulting in concrete erosion and structural weakening. Traditional repair methods often fail to restore the original load-bearing capacity adequately. This study investigates an innovative method for renovating water and sewer manholes using a three-layer coating of polyurea and closed-cell rigid foam. The chemical degradation of manholes leads to significant concrete loss, necessitating robust repair methods. Finite Element Method (FEM) analyses were conducted on axisymmetric manhole structures subjected to soil pressure and tanks with internal water pressure, considering existing concrete damage.

This study employed FEM to simulate the structural behavior of damaged manholes under various loading conditions. A three-layer repair coating comprising polyurea and closed-cell rigid foam was applied to address these damages. Numerical homogenization was used to reduce the complex cross-section of the repaired manhole to a single equivalent layer, facilitating simplified yet accurate structural analysis. The homogenization process enabled the transformation of the geometrically complex cross-section into an effective single layer with equivalent properties. This approach allowed for the re-evaluation of the manhole's load-bearing capacity, demonstrating significant improvements due to the innovative repair method.

This research underscores the efficacy of using a three-layer polyurea and closed-cell rigid foam coating for manhole renovation. The combination of FEM and homogenization techniques provided a reliable framework for assessing and enhancing the structural integrity of repaired manholes. This study's findings support the adoption of this innovative repair method, promising improved durability and performance of water and sewer infrastructure. This work contributes to the field of civil engineering by presenting a practical and effective solution for extending the lifespan of critical infrastructure elements.