Towards a more effective and reliable salt crystallisation test for porous building materials : Experimental research on salt contamination procedures and methods for3 assessment of the salt distribution

International audienceThe RILEM TC ASC-271 is developing a new laboratory test to assess the durability of porous building 36 materials to salt crystallisation. The test encompasses two phases: salt accumulation and damage 37 propagation. This paper focuses on designing a procedure for the accumulation phase; this is considered 38 successful when salts crystallise at the material's evaporative surface (common situation observed on site) without the occurrence of damage. Two procedures were developed and tested on two limestones with 40 different porosity: (1) capillary absorption of a salt solution followed by drying, and (2) continuous 41 capillary absorption. Sodium chloride or sodium sulphate solutions were used. Several methods for 42 assessing the salt distribution were employed: ultrasonic pulse velocity, drilling/scratching resistance, 43 hygroscopic moisture content, ion chromatography, scanning electron microscopy, and micro X-ray 44 fluorescence. The results enabled the selection of the most effective protocol for the salt accumulation 45 phase. 4