Do environmental conditions determine whether salt driven decay leads to powdering or flaking in historic Reigate Stone masonry at the Tower of London?

Research at the Tower of London reveals that while environmental conditions influence salt-driven decay in Reigate Stone masonry, they do not solely determine whether it leads to powdering or flaking. The study found that mineralogical composition and pre-existing damage play significant roles in shaping decay patterns. By analyzing salt content using ion chromatography and simulating decay through accelerated ageing, the team demonstrated that NaCl dominates in powdering while NaNO3 is more prevalent in flaking. However, physical variations in the stone, including mineralogy and historical features like crusts and cracks, were more influential than environmental factors in determining decay rates and patterns.

Michette, M., Viles, H., Vlachou, C., & Angus, I. (2022). Do environmental conditions determine whether salt driven decay leads to powdering or flaking in historic Reigate Stone masonry at the Tower of London? Engineering Geology, 303, 106641. https://doi.org/10.1016/j.enggeo.2022.106641