## 2 Materials and Methods
### Methods and Evaluation Techniques  
Three 100 g batches of RS were heated in a fixed electric oven for 120 min at 750 \({}^{\circ}\)C, 830 \({}^{\circ}\)C, and 900 \({}^{\circ}\)C \(\pm\) 2 \({}^{\circ}\)C for evaluating the BT, which allowed for the total dehydroxylation process to occur, and the resulting materials were finely ground to below 90 um in an FP6 mill (10 min at 450 rotations per minute) and characterised by XRD analysis. The chemical analyses of the CSA binder, RS, and TTRS (obtained at the optimal synthesis temperature (TTRSBT)), determined using the X-ray fluorescence equipment (Explorer S4, BRUKER, Karlsruhe, Germany), are displayed in Table 1, and the most important CSA cement mineralogical phases are also shown. The XRD patterns of the RS and the three TTRS (Figure 1) were collected using a MINFLEX 600 (RIGAKU, Tokyo, Japan) diffractometer with CuK\(\alpha\) radiation and a scan rate of 0.02\({}^{\circ}\)/step. The following four CSA-based cements were examined: a pure CSA cement (C_R) and three CSA binders containing TTRSBT as a substitute for part of the C_R (15%, 25%, and 35% by mass; C_15, C_25, and C_35, respectively). Cemertitious pastes were obtained by employing a water-to-cement (\(w/c\)) ratio of 0.50, and they were transferred into plastic cylindrical containers and stored in thermostatically controlled water (20 \({}^{\circ}\)C). After each chosen curing period (comprised in the interval of 4 h to 56 days), the hardened cylindric pastes were broken into the following two parts: one piece that underwent MIP analysis (Pascal 240 and 140, Thermo-Finnigan, Segrate (MI), Italy, Series porosimeters) and one that was milled (grain size of <90 um) for the DT-TG (using NETZCH-TASC 414/3 equipment, Selb, Germany, operating at 10 \({}^{\circ}\)C/min in air) and XRD (using a D4 Endeavor, Bruker, Karlsruhe, Germany apparatus with CuK\(\alpha\)-radiation and a scan rate of 0.02/step) analyses. The hydration stoppage was carried out by means of a solvent exchange method employing acetone (to remove free water) and diethyl ether (to reduce the acetone evaporation time), and finally, the hardened samples were stored in a desiccator over silica gel and soda lime to mitigate the actions of the water vapour and carbonation, respectively. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline  & \multicolumn{2}{c}{**Chemical Composition**} & \multicolumn{3}{c}{**Mineralogical Phase Composition**} \\ \hline  & \multicolumn{2}{c}{**CSA**} & \multicolumn{1}{c}{**RS**} & \multicolumn{1}{c}{**TTCRSBT**} & \multicolumn{1}{c}{**CSA Cement**} & \multicolumn{1}{c}{**ICDD Ref.**} & \\  & \multicolumn{1}{c}{**Cement**} & & & & & **Number** & \\ \hline CaO & 44.58 & 9.05 & 10.10 & Ye’elimite & 30-0256 & 43.0 \\ \hline SiO\({}_{2}\) & 8.95 & 51.86 & 58.11 & \(\beta\)-belite & 33-0302 & 21.7 \\ \hline Al\({}_{2}\)O\({}_{3}\) & 22.42 & 13.48 & 15.26 & Celite & 38-1429 & 3.8 \\ \hline Fe\({}_{2}\)O\({}_{3}\) & 1.86 & 5.16 & 5.10 & Anhydrite & 37-1496 & 19.1 \\ \hline TiO\({}_{2}\) & 1.10 & 0.65 & 0.76 & Calcite & 05-0586 & 1.1 \\ \hline K\({}_{2}\)O & 0.30 & 1.74 & 1.94 & Brownmillerite & 30-0256 & 4.5 \\ \hline MnO & 0.08 & 0.15 & 0.17 & Gehlenite & 73-2041 & 1.6 \\ \hline Na\({}_{2}\)O & 0.08 & 0.81 & 0.90 & Others & & 5.2 \\ \hline MgO & 0.94 & 2.04 & 2.26 & & & \\ \hline SO\({}_{3}\) & 16.85 & 0.22 & 0.46 & & & \\ \hline P\({}_{2}\)O\({}_{5}\) & 0.05 & 0.15 & 0.18 & & & \\ \hline L.o.i * & 2.16 & 14.50 & 2.70 & & & \\ \hline Total & 99.37 & 99.81 & 97.94 & Total & 100.0 \\ \hline \hline \end{tabular}
*L.o.i, loss on ignition evaluated at 950 \({}^{\circ}\)C \(\pm\) 10 \({}^{\circ}\)C.  
\end{table} 
Table 1: Chemical and phase compositions (solely for the C_R) of the employed cement components (mass %). For the dimensional stability (expansion-shrinkage) tests, 24 prisms of cementitious paste (15 \(\times\) 15 \(\times\) 78 mm) were put into air at an ambient temperature for 24 h, and afterwards, they were demoulded.