# Characterization of Responsive Plasters for Passive Moisture and Temperature Control
## 3 Results and Discussion  
As one can see (Table 2), the obtained results point to the substantial effect of the SAP and PCM admixtures applied in terms of basic material properties. In particular, a notable decrease in bulk density was observed according to the lowered density of the applied admixtures as well as the increased water dosage. Namely, the bulk density was dropped from the initial 1604 kg/m\({}^{3}\) for reference plaster to about 20% for the PSC5 mixture. Taking into account the minor effect of the applied admixtures on matrix density, the total open porosity was shifted up to 41%, i.e., about 15% higher compared to the reference mixture. A better understanding of the observed changes in the material structure is accessed in Figure 3 with the help of Mercury Intrusion Porosimetry. Here, the modified plasters exhibited a significant increase in the macroporous range, while the micro- and mesoporous ranges did not result in such intensive changes. A possible explanation can be found in the increased w/b ratio that promoted the formation of larger voids. On the other hand, the application of SAP with great swelling capability can be viewed as a factor that influenced void creation. After the initial mixing period, the SAP particles absorbed a substantial amount of water which remained swollen during the formation of the solid structure. The consequent slow liberation of the water contained in the SAP particles may result in the internal curing of the mixtures, which could promote the pozzolanic reaction of the applied PCM composite. As reported, internal curing may results in the healing of small pores due to the hydration of unreacted particles; however, this phenomenon is more distinct for concrete mixtures [45]. The limited changes in the micropores' formation can be assigned to the filling of voids with very fine PCM composite particles. The described effects are more visible for mixtures with higher admixture dosages. Since the macropore volume correlates with the mechanical performance of the cementitious materials, a notable drop in flexural strength can be expected [46]. The mechanical parameters of the modified plasters are displayed in Figure 4. As revealed, a gradual decrease in flexural strength resulted in a drop from the initial 1.46 MPa to 0.76 MPa. In other words, the applied modification has a negative effect, despite the pozzolanic activity of the diatomic-based PCM composite. This fact can be assigned predominantly to the adverse effects of the used SAPs on mechanical strength due to the particle swelling and consequent formation of larger voids. Internal curing secured by SAPs may provide some benefits; however, this phenomenon is more relevant for concrete mixture maturing since the w/b ratio is usually substantially lowered, thus the number of unreacted cement particles remains higher. Considering the characteristics of the applied admixtures, notable contradictory effects can be observed. While the pozzolanic activity contributes to the preservation of mechanical performance, the increased w/b ratio, and the shift in macroporous range due to SAP swelling, worsened the strength of the materials. Looking at the pull-out test results, only minor changes can be distinguished. This parameter of the plasters, very important for the construction practice, remained almost unchanged for almost all studied plasters without any significant deterioration. The application of the inert PCM admixture usually led to the significant deterioration of functional properties; on the other hand, the use of tailor-made admixtures with extended functionality and good compatibility with the cementitious composite does not pose a significant barrier to the building practice. In this sense, the applied SAP particles increased the adhesion, as a critical parameter for the application of plasters.