MICRO-CT ANALYSIS APPLIED TO LIME MORTARS FOR DAMAGE ASSESSMENT DUE TO ACCELERATED WEATHERING C&E RESEARCH GROUP Dulce Elizabeth Valdez Madrid*, Nele De Belie, Veerle Cnudde Introduction Weathering of construction materials is one of the main causes for building deterioration and failure. Amongst some of the most important factors contributing to this outcome is the presence of salts in the system and their crystallization/dissolution behavior during ageing. These salts occupy the space within the pore network of the materials and manifests itself only once some damage has already been caused. It is of outmost importance to develop efficient methods for testing, evaluating and development of damage prediction of this phenomena to obtain better and more durable materials. Research questions – Can lime-based mortars show any representative damage due to salt damage? – Is it possible to assess and quantify damage caused by salt crystallization and weathering inside the porous media in a non- destructive manner? – Can a lab-based protocol imitate real life weathering damage without destroying the samples? Experimental conditions Six lime-cement mortars were tested for NaCl weathering by comparing two different contamination and propagation of damage regimes. These regimes consist of cycles of temperature and relative humidity variations followed by rewetting steps with water. Contact dulceelizabeth.valdezmadrid@ugent.be https://pprogress.ugent.be/index.php Universiteit Gent @ugent https://www.linkedin.com/in/dulzabeth/ Methodology For the non-destructive damage assessment, high resolution X-ray micro-computer tomography will be used as a non-traditional characterization technique before and after weathering [Fig. 1]. Weathering by salt damage tests were performed under similar experimental conditions to assess the impact of water and the length of temperature and relative humidity samples on the durability of the mortars. This project has received funding from the European Union’s Horizon 2020 research and innovation programme under Marie Sklodowska-Curie project SUBLime [Grant Agreement n.º 955986]. 150.00 155.00 160.00 165.00 170.00 175.00 180.00 185.00 190.00 Weight (grams) 1:0:3 4:1:15 2:1:9 1:1:6 1:2:9 0:1:3 CYCLE 1 CYCLE 2 CYCLE 3ContaminationDryingWeatheringRewettingDryingWeatheringRewettingDrying Weathering 150.00 155.00 160.00 165.00 170.00 175.00 180.00 185.00 190.00 195.00 Weight (grams 1:0:3 4:1:15 2:1:9 1:1:6 1:2:9 0:1:3 CYCLE 1 CYCLE 2 CYCLE 3 CYCLE 4ContaminationDryingWeatheringRewettingDryingWeatheringRewetting WeatheringRewettingDrying WeatheringDrying Figure 3. Test 2 photographic documentation and weight monitoring results expressed in grams. Lower mass fluctuations and final mass gains are observed by the end of the 4th cycle (Fig. 5). Figure 2. Test 1 photographic documentation and weight monitoring results expressed in grams. Significant mass gains are observed by the end of the 3rd cycle (Fig. 5). 0.29 0.17 0.36 0.51 0.36 0.00 0.05 0.11 0.15 0.07 0.02 0.01 1.72 3.40 2.39 2.27 2.58 2.51 0.30 0.29 0.36 0.42 0.50 0.33 0.00 1.00 2.00 3.00 4.00 1:0:3-1 4:1:15-1 2:1:9-1 1:1:6-1 1:2:9-1 0:1:3-1 1:0:3-2 4:1:15-2 2:1:9-2 1:1:6-2 1:2:9-2 0:1:3-2 Relative difference of masses before and after testing (%) Debris (%) TEST 1 TEST 2 Figure 5. Final relative mass differences obtained before and after weathering (light blue), including final mass of total resulting debris (dark blue). DIFFERENCE IN MASS BEFORE AND AFTER TESTING Accelerated weathering There are currently some protocols and recommendations to test materials’ performance towards salt crystallization. Nevertheless, these are mainly focused on rocks, bricks and masonry units, aiming towards failure. This research intends to propose a more suitable protocol for mortars that allows for the characterization of the salt crystallization and its products in a more reliable and quantifiable manner, based on the RILEM TC ASC-271 recommendations. After 4th cycle Initial s