## 3 Results and Discussion  
Table 1 shows the chemical composition of CSA cement, WPSs and TTWPSs; it also reports the mineralogical composition of CSA cement determined using the Rietveld method whose results were normalized to 100% of the accounted crystalline phases. From the chemical analysis it can be argued that CSA cement was mainly composed of CaO, Al\({}_{2}\)O\({}_{3}\), SO\({}_{3}\) and SiO\({}_{2}\), in that order; the Rietveld analysis indicates that the main crystalline components of the CSA cement were in the following order: ye'elimite (43.0 mass%), belite, brownmillerite, celite (3 CaO\(\cdot\)Al\({}_{2}\)O\({}_{3}\)) and gehlenite (2 CaO\(\cdot\)Al\({}_{2}\)O\({}_{3}\cdot\)SiO\({}_{2}\)); furthermore, CaSO\({}_{4}\) was also present, mainly from the addition of natural anhydrite. The chemical composition of TTWPS reveals that SiO\({}_{2}\) (47.7 mass%) and Al\({}_{2}\)O\({}_{3}\) (34.8 mass%) were the main oxides; CaO (6.3 mass%) and Fe\({}_{2}\)O\({}_{3}\) (3.0 mass%) were present as secondary components, while fairly low amounts of SO\({}_{3}\), MgO, K\({}_{2}\)O and Na\({}_{2}\)O were also found. The specific surfaces for both CSA and TTWPSs (measured according to EN 196-6) were equal to 4500 \(\pm\) 50 and 4300 \(\pm\) 50 cm\({}^{2}\)/g, respectively; D\({}_{10}\) and D\({}_{90}\) values for the two materials were very similar to each other, 2.5 \(\upmu\)m and 3.1 \(\upmu\)m and 67.3 \(\upmu\)m and 72.7 \(\upmu\)m for CSA cement and TTWPSs, respectively. Figure 1 shows the e/s curves (in terms of length changes) for CSAR, CSA20 and CSA35. They indicate that the three systems differed very little from each other, both when submerged under water and cured in air. The maximum expansion values were reached after about 15-20 days of curing and were in a very narrow range (0.02-0.06%). When air cured, TTWPS-based pastes showed a rapid shrinkage during the first five days of hydration; for both systems, the minimum shrinkage value (\(-\)0.18% for CSA20 and \(-\)0.20% for CSA35) was reached after about 20 days of curing; however, a less rapid shrinkage was exhibited by the CSAR system which approached a steady value (almost \(-\)0.18%) only after about 20 days of hydration. Figure 2 reports the mechanical compressive strength values for CSA-based mortars at different curing times (4 and 16 h, 1, 2, 7, 28 and 56 days); the CSAR compressive strength values were higher than those of the two blended cements at the shortest curing period (22% and 54% higher than those of CSA20 and CSA35 systems, respectively); with an increase in curing time, the mechanical compressive strength gap reduced for the three systems. Finally, after 28 and 56 days of curing, the CSA20-based mortars exhibited almost identical compressive mechanical strength values as the reference mortar; however, the compressive mechanical strength values of the CSA35-based mortars were about 25% and 18% lower than those of the CSAR at 28 and 56 days of curing. Figure 3 displays the DT (left)-TG (right) results for CSAR, CSA20 and CSA35 aged for periods in the range 4 h-56 days. According to data from scientific literature [65], the following phases, in the order of increasing temperature of the related endothermal effect, were attributed to calcium silicate hydrates (C-S-H), ettrinigite (E), aluminum hydroxide (AH\({}_{3}\)) and calcium carbonate (CC); these phases were observed at 117 \({}^{\circ}\)C \(\pm\) 3 \({}^{\circ}\)C, 159 \({}^{\circ}\)C \(\pm\) 9 \({}^{\circ}\)C, 281 \({}^{\circ}\)C \(\pm\) 5 \({}^{\circ}\)C and 725 \({}^{\circ}\)C \(\pm\) 7 \({}^{\circ}\)C.  
Figure 1: Dimensional stability curves for CSAR, CSA20 and CSA35 pastes (air and water cured) at a w/b of 0.65. Figure 2: Compressive strength measurements for CSAR, CSA20 and CSA35 mortars cured within the period 4 h-56 days. Negligible exo-/ endo-thermal effects were found above 600 \({}^{\circ}\)C; in fact, weight losses in the range 600 \({}^{\circ}\)C-1000 \({}^{\circ}\)C were always lower than 2.3% which means, according to [57], that carbonation process was minimal.