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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3.5. Heat and moisture transfer simulation tests Figure 7 plots Heat flux measured over time on the inner and outer sides of a mortar plate subjected on one side to the action of a climate chamber described in Figure 2 to simulate heating-cooling and wet-dry cycles. Continue lines corresponded to the side in contact with constant laboratory conditions, which was considered the interior in the simulation, while dashed lines corresponded to the side in contact with the climate chamber, which was considered the exterior and variable climate conditions. During a cooling cycle (Fig. 7) it was observed that the reference mortar plate took at 40 minutes to begin heat transfer on the laboratory side (interior conditions). All samples with SAP and PCM delayed the transmission time up to 60 minutes. The incorporation of SAP with spherical particles produced a longer delay than SAP with irregular shape particles. This difference can be related to the different water absorption capacity of each SAP type. When PCM was incorporated, no difference was observed on the delay time. However, mortars with PCM increased the total heat energy accumulated on the side in contact with the climate chamber (dashed lines) and, therefore, acted as heat buffer, as expected. During a wetting cycle, heat flux though the mortar plate was also affected by the incorporation and type of SAP. Spherical SAP reduced the heat transfer due to its larger water absorption capacity when compared to irregular SAP, acting in both cases as moisture buffers. 4. Conclusions An experimental study reporting materials selection, mortar composition design and experimental tests and procedures used to assess thermal and moisture self-modulating properties of PCM and SAP modified mortars for architectural applications as buffer layers was presented. A pervious cement-lime mixture was designed and different amounts and combinations of two types of SAP (spherical and irregular particle shape) and a microencapsulated PCM were evaluated. Mortars’ fresh workability and setting and hardened physical and mechanical prope rties, microstructure, thermal (heat conductivity and storage properties) and hygric parameters (water and vapor transport and storage) and long term carbonation were studied. The aim of the study was to design pervious rendering cement lime mortars with bio-based components for indoor architectural applications acting as heat and moisture buffer to enhance indoor comfort conditions, delaying the effect of climate fluctuations and the need to activate active air conditioning systems. It was found that the incorporation of SAP required more water to improve workability and slightly improved mechanical hardened mortar performance, reduced water permeability and reached class Good as moisture buffer. When combined with PCM, rendering mortars also required more water and slightly reduced density, increased microporosity and moderated hygric and mechanical performance. Nevertheless, PCM reduced thermal conductivity and remarkably increased thermal enthalpy, acting as a thermal buffer when subjected to heating and cooling cycles. Acknowledgements The authors acknowledge with thanks the funding provided by the Reasearch Program for the Promotion of Young Researchers, co-funded by Comunidad de Madrid and the University of Alcala (Spain), as part of the project IndoorComfort (CM/JIN/2019-46) and the Project: GA-101086440 — BEST of the Marie Skłodowska -Curie actions - Staff Exchanges call HORIZON-MSCA-2021-SE-01, funded by the European Union. Some of the components were supplied by BASF Construction Chemicals España S.L and Cementos Portland Valderrivas. References Cunha, S., Lima, M., Aguiar, J.B., 2016. Influence of adding phase change materials on the physical and mechanical properties of cement mortars, Construction and Building Materials 127, 1 - 10 Fořt , J, Kočí , J, Pokorný, J, Černý , R., 2020. Influence of Superabsorbent Polymers on Moisture Control in Building Interiors. Energies 13 (8), 2009. Guardia, C., Barluenga, G., Palomar I., Diarce G., 2019. Thermal enhanced cement - lime mortars with phase change materials (PCM), lightweight aggregate and cellulose fibers. Construction and Building Materials 221, 586 - 594.