Salt crystallisation and weathering in masonry retaining walls: A multiphase modelling approach

This study presents a numerical investigation into the effects of salt crystallisation-induced weathering on masonry earth-retaining walls, with a specific focus on historic quay walls in Amsterdam. A multiphase modelling strategy is adopted to simulate moisture and salt transport, capturing the impact of environmental exposure on these ageing structures. The numerical model is first applied with masonry assumed as a homogeneous continuum and is subsequently refined to incorporate masonry texture. The influence of boundary conditions, multiple weathering cycles, and long-term humidity variations is examined to assess salt accumulation patterns. Results indicate that evaporation pathways significantly influence crystallisation depth, while explicitly modelling masonry texture leads to greater salt accumulation. Furthermore, an analytical estimation of the effective Young's modulus suggests that salt deposition within pores may contribute to through-thickness stiffness variations observed in experimental studies on samples collected from a multi-wythe masonry bridge pillar, with masonry type and exposure conditions comparable to those of Amsterdam's quay walls. These findings provide new insights into the deterioration mechanisms of historic quay walls and highlight the importance of considering environmental effects in their structural assessment.