Experimental and numerical investigations on traditional and bio-based porous building materials: durability as a key to sustainability

The durability of porous building materials plays a pivotal role in achieving a sustainable built environment. As operational energy demand decreases, embodied emissions associated with materials and construction become increasingly significant, making durability a key lever to reduce resource consumption. This doctoral research investigates how degradation mechanisms govern the long-term performance of both traditional and biobased porous building materials through a combined experimental–numerical approach. The first research strand focuses on salt crystallization-induced damage in traditional materials such as tiles, bricks and stones. A micromechanical finite element framework was developed to simulate crystallization pressure acting on pore walls and to generate a dataset of degradation scenarios. From these, a highly efficient phenomenological damage model was derived and coupled with a multiphase transport model, enabling predictive simulations of salt weathering. The results reproduced experimentally observed transport and degradation trends, demonstrating how pore-scale phenomena can be upscaled into efficient macro-scale models for durability assessment. The second strand addresses moisture-induced degradation in bio-based building materials. An experimental campaign established relationships between composition, mechanical performances and hygrothermal properties, while accelerated aging and X-ray microtomography revealed the dominant sources and mechanisms of damage. Image-informed mesoscale finite element models, calibrated against experimental data, successfully reproduced these processes and provided a robust basis for the assessment of long-term durability in bio-based building materials. Together, the two strands form a unified multi-scale framework linking micro- and meso-scale damage to macroscopic deterioration. The research advances the understanding of degradation in porous building materials and delivers validated tools for predictive durability assessment. These outcomes contribute to the design of longer-lasting building materials and support durability-oriented strategies for a more sustainable built environment.