## 3 Results
### X-ray Diffraction Findings  
The XRD patterns for pastes OPC, M1 (70%OPC + 20%U\({}_{\text{C\&DW}}\) + 10%BA) and M2 (55%OPC + 20%U\({}_{\text{C\&DW}}\) + 20%BA + 5%SF) soaked in water or exposed to the aggressive media analysed are reproduced in Figures 4-7. The crystalline compounds identified in the water-soaked OPC specimens (Figure 3) included primarily calcium monocarbouluminate (CH\({}_{22}\)Al\({}_{2}\)Ca\({}_{4}\)O\({}_{20}\)), ettrinigite (CaO)\({}_{6}\)(Al\({}_{2}\)O\({}_{3}\))(SO\({}_{3}\))\({}_{3}\cdot 32\)H\({}_{2}\)O), portlandite (Ca(OH)\({}_{2}\)), calcite (CaCO\({}_{3}\)) and anhydrous dicalcium silicate (C\({}_{2}\)S) in the form of larnite, a mineral present in portland cement detected by XRD after soaking in water because it hydrates more slowly than other mineralogical phases in the cement [58]. Figure 4: XRD patterns for 56-d-soaked pastes: OPC, M1 and M2 (Note—E: ettrinigite; CA: calcium monocarbouluminato; P: portlandite; Q: quartz; O: orthoclase; A: Albite; C: calcite; and B: belite). Figure 5: XRD patterns for 56 d OPC, M1 and M2 exposed to seawater (Note—E: ettrinigite; M: brucite; P: portlandite; Q: quartz; O: orthoclase; A: Albite; C: calcite; and B: belite). The same phases as observed in OPC were identified in phases M1 and M2, along with quartz and the feldspars albite and orthoclase present in the SCMs used, as discussed in Section 2.1. The intensity of the portlandite reflections declined as a result not only of lower cement content, but also of the pozzolanic reaction induced by the U\({}_{\text{C\&DW}}\), BA and SF added. The calcium monocarboaluminate observed in the water-soaked specimens was absent in the pastes exposed to seawater (Figure 5). The diffractograms for the latter also contained lines for other crystalline compounds resulting from the reaction between hydration products and the sulphate and chloride ions in seawater. The Cl\({}^{-}\) ions diffusing through paste pores were partially retained by the phases bearing Al\({}_{2}\)O\({}_{3}\), giving rise to calcium monochloraluminate hydrate or Friedel's salt (3 CaO: Al\({}_{2}\)O\({}_{3}\)-CaCl\({}_{2}\)\(\cdot\)Al\({}_{2}\)O\({}_{3}\)\(\cdot\)10H\({}_{2}\)O) [59; 60], from which ettringite may have formed via reaction with SO\({}_{4}\)\({}^{-}\) ions [4]. Brucite (Mg(OH)\({}_{2}\)) also formed as the product of the reaction between the Mg\({}^{2+}\) in the seawater and the OH  
Figure 6: XRD patterns for 56-d OPC, M1 and M2 exposed to 0.5 M NaCl (Note—E: ettringite; F: Friedel’s salt; P: portlandite; Q: quartz; O: orthoclase; A: Albite; C: calcite; and B: belite). Figure 7: XRD patterns for 56 d OPC, M1 and M2 exposed to 0.3 M Na\({}_{2}\)SO\({}_{4}\) (Note—E: ettringite; G: gypsum; CA: calcium monocarboaluminato; P: portlandite; Q: quartz; O: orthoclase; A: Albite; C: calcite; and B: belite). ions present in portlandite [61]. The brucite diffraction lines were more intense in the OPC than in M1 or M2 (see Section 3.4). The lines for portlandite were significantly less intense inn the seawater- than in the water-soaked specimens, from which seawater may be inferred to have attacked that hydration product directly. In contrast, the ettrinigite and calcite lines were more intense due to the interaction between the phases in the paste and the sulphates and carbonates present in seawater, resulting in the formation of secondary ettrinigite [62] and calcite [61]. The pastes exposed to 0.5 M NaCl (Figure 6) were observed to form Friedel's salt as a product of the reaction between phases C\({}_{3}\)A and C\({}_{4}\)AF, thereby limiting the secondary formation of ettrinigite, an expansive mineral with a consequently adverse effect on cement-based materials. The intensity of the respective diffraction lines was greater in pastes M1 and M2 than in OPC. The intensity of the lines for ettrinigite remained unchanged relative to the water-soaked pastes, a finding consistent with [PERSON] et al. [63] reports to the effect that ettrinigite remains stable at NaCl concentrations of 0.5 M or lower.