Salt weathering in granitoids: an overview on the controlling factors

Historically granite is one of the most applied building materials worldwide. Building stones should accomplish several properties required by different testing materials standards. Salt weathering affects the aesthetical properties of the stones and eventually diminish their durability. The use of weathered granites has increased in the last several decades, but their behavior under adverse environmental conditions requires continued investigation. The use of salt for the prevention of ice formation in colder climates can have harmful consequences on high-porosity stones. Twenty-eight different stones, mostly granitoids, all of them often used as dimensional building stones, were subjected to the salt bursting test. The porosity and the pore network are important parameters in salt weathering; therefore, the pore radii distribution and capillary water uptake were measured. The capillary pores and related porosity are the main factors controlling the behavior of the studied stones under salt action. However, the pore radii size and distribution also plays an important role. In some cases, the salt action is only visible after a high number of test cycles, thus making the actual salt test standards unrealistic.