Salt weathering: a selective review

The past decade has seen a growing scientific interest in the still poorly understood subject of salt weathering, a phenomenon with significant cultural and economic consequences. This interest has led to an increase in research results and growing clarification of the roles salts play in weathering and decay. The development of improved mitigation methods to reduce the decay of building materials by salts has been a slow process, often arising from the analysis of unique field situations and otherwise dependent on simplified laboratory experiments and computer modelling. Collecting, reviewing, synthesizing and disseminating the existing data on salt weathering is a difficult task. The size and scope of the topic are mirrored in the diverse disciplines that have historically contributed to understanding the action of salts in porous materials and mitigation methods. Nevertheless, an appreciation of existing, even contradictory, data is an important tool for increasing understanding. There are now over 1800 research articles on the topic of salt weathering originating from several disciplines, as well as over 6000 references on the general problems of building material decay. In order to navigate such a vast collection of data and knowledge, this article describes the multidisciplinary nature of the study of salt damage to porous building materials, provides a framework for considering the complexity of salt damage, and serves as a selective literature survey largely focused on recent work and those articles with relevance for conservation.