## 4 Experimental Program
### Tests and Methodology  
A two-stage experiment was designed. The aim of the first stage was to estimate the initial TES abilities of the selected materials including the fireproof concrete (with the ceramic aggregate). The test stand was equipped with a ceramic base, an electronic thermometer, and a laboratory dryer, which can heat the specimens to a temperature of 230 \({}^{\circ}\)C.  
The room temperature was 25.4 \({}^{\circ}\)C. Samples were placed in the laboratory dryer and its maximum working temperature (230 \({}^{\circ}\)C) was set. The dryer reached the temperature after one hour and 15 min. At this temperature, the specimens were placed for three hours, after which they were removed from \begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{2}{*}{**Feature**} & \multirow{2}{*}{**Unit**} & \multicolumn{4}{c}{**Concrete Type**} & \multirow{2}{*}{**Test Method**} \\ \cline{3-3} \cline{5-6}  & & **CGA-PC** & **CGA-AC** & & **CCA-PC** & **CCA-AC** \\ \hline Bulk density & kg/m\({}^{3}\) & 2269 (0.36) & 2238 (0.22) & 2178 (0.32) & 2165 (0.28) & EN 12390-7 \\ \hline Water absorption & \% & 3.24 (2.35) & 3.11 (1.70) & 3.79 (2.21) & 3.98 (2.46) & According to [45] \\ \hline Open porosity & \% & 7.35 (2.12) & 6.96 (1.63) & 8.25 (2.08) & 8.62 (3.11) & According to [45] \\ \hline Compressive strength & MPa & 49.9 (1.61) & 56.4 (1.49) & 74.5 (2.46) & 88.6 (4.50) & EN 12390-3 \\ \hline Coefficient of variation in brackets. CGA-PC: concrete with gravel aggregate and Portland cement; CGA-AC: concrete with ceramic aggregate and Portland cement; CCA-AC: concrete with ceramic aggregate and alumina cement. & & & \\ \hline \hline \end{tabular}
\end{table} 
Table 6: Basic features of the concretes used in the study. \begin{table}
\begin{tabular}{c c c c} \hline \hline \multirow{2}{*}{**Property**} & \multicolumn{4}{c}{**Type of Cement**} \\ \cline{2-4}  & **Unit** & **High Alumina G\#Kal 70** & **CEM I 42,5N\(-\)SR 3/NA** \\ \hline Blaine specific surface area & cm\({}^{2}\)/g & 4000–5000 & 3688 \\ Beginning of the binding time & min & \(\geq\)75 & 233 \\ End of the binding time & min & \(<\)240 & 291 \\ Compressive strength after 6 h & MPa & \(>\)18 & - \\ Compressive strength after 24 h & MPa & \(>\)30 & - \\ Compressive strength after 2 days & MPa & - & 23.9 \\ Compressive strength after 28 days & MPa & - & 55.9 \\ Specific density & g/cm\({}^{3}\) & 2.96 & 3.01 \\ Cl content & \% & \(\leq\)0.10 & 0.07 \\ SO\({}_{3}\) content & \% & \(\leq\)0.50 & 2.77 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Basic properties of the cements used to manufacture the tested concretes. \begin{table}
\begin{tabular}{c c} \hline \hline \multicolumn{1}{c}{**Component**} & **Amount (kg/m\({}^{3}\))** \\ \hline Alumina/Portland cement & 493.38 \\ Fine aggregate 0–4 mm & 991.37 \\ Coarse aggregate 4–8 mm & 396.55 \\ Water & 201.38 \\ \hline \hline \end{tabular}
\end{table} 
Table 5: The concretes’ mix proportions. the dryer and laid upon a ceramic base. The samples' temperature was measured using a digital thermometer by applying a probe to the surface of the sample in the middle of its length. The samples used in the experiment, together with the test stand, are shown in Figure 1. On the basis of the results obtained, the materials' thermal power was calculated, using Equations (1) and (4). The second stage was a re-run of the experiment, but it was assumed to heat the samples to the temperature similar to these prevailing in the fireplace. The aim was to assess the thermal power in the operational temperature range of the fireplace. The test stand was equipped with the PK 1100/1 furnace (Thermolab S.C, Warsaw, Poland), which was controlled by a PC, and the infrared camera (Fir, Boston, MA, USA) was a FLIR123 model. The thermocouples, which are an integral part of the furnace, were used to measure the temperatures. The readings from the thermocouples were recorded on the PC. The scheme and the furnace are shown in Figure 2.  
The samples tested were the same as the ones used during the first stage of the TES assessment.