Influence of the salt crystallization in the durability of granites used in vernacular masonry buildings

Abstract

The present paper presents an experimental campaign of salt crystallization cycles on seven distinct types of granites, which are characteristic of vernacular construction, and discusses the main results, analysing the major damage associated to the weathering process of the granites. The granites adopted in the present work were collected from the Northern region of Portugal. A total of 54 specimens were tested to the action of salt crystallization cycles according to the EN 12370 (1999) standard. The analysis of the progress damage resulting from the salt crystallization cycles was made based on the: (1) visual inspection; (2) dynamic modulus of elasticity; (3) apparent volume; (4) variation on the ultrasonic pulse velocity; (5) physical properties (water absorption by immersion and by capillary and porosity). From the results obtained it was observed that the crystallization test strongly affected the building stones under analysis. The granites that have a higher number of pores and capillaries allowing the access of water, are potentially more vulnerable to the salt crystallization degradation process.