Abstract Water ponding on low-slope roofs accelerates biofilm colonization, ultimately driving premature failure of roof coatings. Conventional field exposure tests may take years before meaningful performance assessment can be made, hampering product development. In this study, a combined experimental–numerical simulation that determines the ponding water resistance of commercial acrylic coatings within a day has been demonstrated by grafting pre-grown live algae onto the candidate coating surface, followed by the forced drying of the algae, which induces shrinkage within the biofilm and consequently generates internal stresses on the underlying coating, ultimately triggering crack initiation and propagation within the coating. This is in addition to surface erosion caused on the algae-covered coating surface. Full-field surface strains are captured via 2D digital image correlation (DIC). The strain histories are fed into an Abaqus ® finite element method model in which a transversely isotropic thermal shrinkage analog represents algae contraction to simulate the 3D stress distribution. The combined algae grafting/DIC approach delivers quantitative, mechanistic insight into biofilm-induced damage within a day, offering an accelerated tool for roof-coating development and assessment.
Khatri et al. (Mon,) studied this question.