# Cement Pastes with Hygyroscopic Polymeric Additions for Potential Building Applications
## 4 Conclusions  
Four sets of cement pastes were prepared with a commercial premix containing calcium silicates, quartz, and a crystallization admixture, which accelerated the strength development rate. Three sets were prepared with hygroscopic polymer additions of sodium polyacrylate (SA-PA) and/or recycled polyamide fibers (NY) to study the evolution of their pore size distribution, shear mechanical response, and thermal properties at different aging times and after thermal treatment at 200 \({}^{\circ}\)C. From the study, it was hypothesized that the behavior of cement pastes depends on the type of polymeric addition; the conclusions are listed below. 1. Hygroscopic polymeric additions make cement paste less workable than CS, because they rapidly absorb water, detracting from its rheological role. 2. The porosity evolution was investigated at different curing stages; mercury intrusion porosimetry (MIP) has been used for investigating pores' evolution during aging and after a heat treatment at 200 \({}^{\circ}\)C. The pore size distribution appeared to be bimodal when sodium polyacrylate was added, as already reported in the literature [20]. The presence of polyamide fibers made the pore size distribution bimodal. This distribution was maintained during aging for up to 28 days. NY/SA-PA was the only sample that maintained the bimodal distribution even after the heat treatment. 3. Under five cycles of loading-unloading shear stress, the samples containing polyamide fibers showed significant visco-plastic deformation until pores cracked at the tip and connected with adjacent pores to form a micro-fracture surface. The micro-fracture surface extended, forming macroscopic cracks, which could eventually lead to shear failure of the cement paste consolidation body along the interface layer. 4. Cement pastes are useful for heat-storing walls or energy-efficient insulation. In the first case, the product ka\({}^{-0.5}\), where k is the thermal conductivity and a is the thermal diffusivity, must be maximized, whereas a\({}^{0.5}\)k\({}^{-1}\) must be maximized in the second case. The cement paste containing sodium polyacrylate (SA-PA sample) maximized both values (9.2 10\({}^{2}\) m\({}^{-2}\) K\({}^{-1}\) s\({}^{0.5}\) W and 1.1 10\({}^{-3}\) m\({}^{2}\) K s\({}^{-0.5}\) W\({}^{-1}\), respectively) due to its high diffusivity. After thermal treatment at 200 \({}^{\circ}\)C, SA-PA showed the highest value for heat-storing (6.3 10\({}^{2}\) m\({}^{-2}\) K\({}^{-1}\) s\({}^{0.5}\)W), whereas the sample containing both nylon fibers and sodium polyacrylate (Ny/SA-PA sample) showed the highest values for energy-efficient insulation (2.6 10\({}^{-3}\) m\({}^{2}\) Ks\({}^{-0.5}\) W\({}^{-1}\)) due to the concurrent presence of macro- and micropores. 5. Further studies will be necessary to confirm the trends in pore distribution and the effects on thermal and mechanical properties. Future research should also consider other cementitious materials to increase the predictive indications for designing large-scale concrete, plaster, coatings, or mortar. **Author Contributions:** Conceptualization, R.D.M., R.A. and G.M. ; methodology, O.C. ; software, O.C. ; validation, R.D.M., G.M. and R.A.; formal analysis, R.D.M. and O.C. ; investigation, O.C. ; resources, R.A., R.D.M. and G.M. ; data curation, R.D.M. ; writing--original draft preparation, R.D.M. and O.C. ; writing--review and editing, R.D.M. and G.M. ; visualization, G.M. ; supervision, R.A.; project administration, R.D.M. ; funding acquisition, R.D.M., R.A. and G.M. All authors have read and agreed to the published version of the manuscript. **Funding:** This research received no external funding. **Data Availability Statement:** The raw data supporting the conclusions of this article will be made available by the authors on request. **Acknowledgments:** The binder called \"Concentrate Xypex\"--PROBAR XYPEX was provided by PROBAR Italia (Comano, Milan, Italy). [PERSON] is acknowledged for the preparation of samples and SEM observations.