PSI - Issue 64

Irene Palomar et al. / Procedia Structural Integrity 64 (2024) 1435–1443 Irene Palomar et al. / Structural Integrity Procedia 00 (2024) 000 – 000

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Hygric characterization of rendering mortars was performed according to standard UNE-EN 1015-19 for capillary absorption and UNE-EN 1015-18 for vapour permeability of hardened samples in dry and wet conditions. Moisture buffer value (MBV) was measured according to Nortest test, as described by Rode et al. (2006). The heat and moisture transfer laboratory simulation under different climatic conditions was performed according to the experimental set-up presented in Figure 2, using a FDM C140SX climatic chamber (0 – 70 °C temperature and 10 – 98% of relative humidity ranges). The door of the chamber was replaced by a 50 mm thick frame of expanded polystyrene (XPS) that closed completely the side of the climatic chamber door. Mortars plate specimens of 220 × 240 × 24 ± 2 mm were tested placed in a hole in the middle of the XPS frame (Fig. 2). Several thermocouples (°C) and relative humidity (%) sensors, heat flux meters and ultrasonic 250 Hz p- and s- waves transducers were located on the mortar plate outside and inside the climatic chamber, as described in Figure 2. Figure 2 also plots the heat flux measured inside and outside the chamber during heating (30º C)-cooling (15ºC) and dry (30 % RH)-wet (70 % RH) cycles. 3. Experimental Results and Analysis Fresh consistency and early age shrinkage and water evaporation were tested to evaluate mortars’ workability and setting. In the hardened state, density, water absorption coefficient and mercury intrusion porosimetry were measured to analyze the effect of SAP and PCM on mortars ’ microstructure. Compressive and flexural stress and ultrasonic velocity pulse propagation were tested to assess the effect of composition on mechanical properties. The use of lime as part of the mortar’s binder makes neces sary to analyze long term carbonation. Thermal and moisture characterization comprised thermal conductivity and enthalpy in heating and cooling cycles and capillary water absorption, vapor permeability and moisture buffer value. Figure 3 summarizes the experimental results of workability and early age performance of mortars with SAP and PCM compared to the reference mixture (REF). Water to binder ratio (w/b) was adjusted to achieve a plastic consistency, ranging between 0.75 and 1. Mortars with SAP required more water to get the target consistency and this amount was not linearly related to the amount of SAP. Larger amount of SAP required some 15 % more water than expected considering the water absorbed by SAP both spherical and irregular, with values of 35g/g and 29g/g, respectively. The incorporation of PCM required more water when combined with spherical SAP. As it could be expected, early age shrinkage increased when SAP and PCM were incorporated to the mixture due to the higher amount of uncombined water required to achieve the target plastic consistency. Mortars with SAP reached values between 0.32 and 0.46 mm/m, and the incorporation of PCM enlarged shrinkage up to 0.42 to 0.62 mm/m. As SAP reduced the amount of uncombined water available in the mixture, SAP diminished evaporation rate The larger amount of water required for mixtures with PCM was available and uncombined, further increasing evaporation rate. However, Evaporation rate was reduced for both SAP and PCM mortars regarding reference mixture. 3.1. Fresh and early age characterization

Fig. 3. Workability and early age performance experimental results of bio-based self-modulating mortars with SAP and PCM.