## 3 Research Results and Discussion  
The density dependencies of the compressive strength and thermal conductivity of the prepared LWC specimens are presented in Figure 2. From the presented figure, it can be seen that the compressive strength and thermal conductivity of LWC also increase with increasing density. Two methods were used to analyse the experimental data: regression analysis and analysis of variance (ANOVA). Regression analysis made it possible to assess the dependence of the values of one quantity on another. The ANOVA statistical  
Figure 1: Test specimens in a bath in a refrigeration chamber before soaking. model allowed us to assess whether the means of different groups are the same. With a dashed line, Figure 2a shows the minimum possible compressive strength values and Figure 2b shows the maximum possible thermal conductivity values calculated with a 95% confidence interval. The dependencies of compressive strength and thermal conductivity coefficient are described by the regression Equations (13) and (14), respectively:  
\[\sigma_{c}=0.00498-0.8045\cdot\rho; \tag{13}\]  
with a determination coefficient \(r^{2}=0.858\) and standard deviation \(S_{r}=0.0725\) MPa, where \(\rho\) is LWC density, in kg/m\({}^{3}\), and  
\[\lambda_{10}=0.00225+0.01925\cdot\rho; \tag{14}\]  
with a determination coefficient \(r^{2}=0.947\) and standard deviation \(S_{r}=0.00191\)\(W/(\text{mK})\). Basically, OPC affects the density. The higher the amount of OPC we add to the prepared mixture, the higher the LWC density we obtain. In this study, we were most interested not in the effect of OPC on density but in the effect of CEPW on both compressive strength and thermal conductivity. In Figure 3, an analysis of the effect of CEPW on the compressive strength and thermal conductivity of the specimens is presented. In the first  
Figure 2: Dependencies of compressive strength (**a**) and thermal conductivity (**b**) on the density of the LWC; \(\circ\)—experimental values. case (Figure 3a), the compressive strength results were compared, when only EG beads were used and when part of the EG was replaced by CEPW aggregate. In the figure, and according to the ANOVA statistical model, the mean of the results is marked with a solid line and the two-sided confidence interval is marked with dashed lines. Analysis of the results shows that the difference in results is not significant. The average values obtained for compressive strength meet the 95% confidence limits, and this indicates that the replacement of part of the EG aggregate with the CEPW aggregate does not affect the compressive strength (or that the influence is insignificant). In the second case, the thermal conductivity results were evaluated (Figure 3b). The analysis of the results showed that the use of CEPW aggregate affects the reduction of thermal conductivity. The average values of the thermal conductivity measurements obtained are not within the range and this means that the results of the specimens made with only EG aggregate, and the specimens with partially replaced aggregate from CEPW, differ significantly. With CEPW, we achieved our goal of significantly reducing thermal conductivity with little or no reduction in compressive strength. Figure 4 shows the dependence of the bending strength on the density. The bending strength values not only allow a more accurate assessment of the effects of density, binder content, and aggregate on the strength characteristics but, also, a comparison with the obtained LWC values obtained in the studies of other authors. Figure 4 shows that, as the  
Figure 3: Analysis of the effect of CEPW on compressive strength (**a**) and thermal conductivity (**b**). LWC density increases, an increase in flexural strength is also observed. To describe the dependence between density and bending strength, we obtained Equation (15):  
\[\sigma_{b}=1.326\cdot p-163.736; \tag{15}\]  
with a coefficient of determination \(r^{2}=0.869\) and standard deviation \(S_{r}=20.86\) MPa.