## 3 Sulfur Cake
### Processing and Modification Technologies
#### 3.2.2 Blending with Additives
The C-H stretching region (2934 and 2845 cm\({}^{-1}\)) remains evident, but the bands are slightly less intense, implying partial thermal degradation or chemical transformation of organic content. The carbonyl band at 1752 cm\({}^{-1}\) is similar but shifted further and is now more distinct, indicating more pronounced incorporation of oxidized sulfur components or bituminous by-products. In addition, the 600-1100 cm\({}^{-1}\) range shows greater and more ordered peaks especially at 1031 and 907 cm\({}^{-1}\), suggesting higher conjugation of C-S and S-O bonds. These changes correspond to a successful procedure of sulfur polymerization or crosslinking, leading to more durable and asphalt- and concrete-ready materials [51]. These spectral changes are highly associated with enhanced mechanical and chemical behavior of modified sulfur-based binders within infrastructures. The formation of stable sulfur-oxygen and carbon-sulfur functional groups plays a role in the increased water resistance, chemical durability, and thermal performance of sulfur concrete, which seems to be an appropriate sulfur-based material for withstanding harsh environments [52]. Similarly, integration between oxidized sulfur species and hydrocarbons at the chemical level facilitates improved adhesion and elasticity in the case of the sulfur-extended hot-mix asphalt, hence improving rutting resistance and service life [53]. The structural reinforcement exhibited in Figure 3 is essential as a consequence of sulfur modification, confirming the functionality of the structural reinforcement for practical applicability in structural reinforcement. The XRD patterns in Figure 3a,b are a comparative analysis of unmodified and oleic acid-modified sulfur cake, respectively. These diffractions provide important differences in phase content and crystal structure, which have direct impacts on their capability to be used in infrastructure applications such as in sulfur concrete and sulfur-modified bitumen. As Figure 3a shows, the complex pattern of the unmodified sulfur cake consists of sharp and intense peaks belonging to orthorhombic sulfur (S\({}_{8}\)), as well as some less intense reflections of calcium sulfate (CaSO\({}_{4}\)) and calcium carbonate (CaCO\({}_{3}\)). These peaks, especially those at d = 5.76 A, 4.89 A, and 3.57 A, point to a highly crystalline state of sulfur. Furthermore, the existence of secondary phases of CaSO\({}_{4}\) and CaCO\({}_{3}\) indicates the incomplete separation \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
\begin{tabular}{c} Improved corrosion \\ resistance, thermal \\ behavior, and mechanical \\ properties \\ \end{tabular} & [45, 46] \\ \hline \hline \end{tabular}
\end{table} 
Table 5: _Cont._of impurities normally contained in the waste of sulfuric acid production. In addition to sulfur purity, these inorganic residues may create problems in the mechanical aspects through the poor brittleness and non-homogeneity of the final binder matrix [6]. Conversely, Figure 3b, representing the sulfur cake modified with oleic acid, demonstrates a cleaner and more refined crystalline. The peaks demonstrate the majority of sulfur with suppressed or reduced CaSO\({}_{4}\) and CaCO\({}_{3}\) signals. This further indicates a good surface passivation or a chemical reaction between the oleic acid and the calcium-based impurities by forming organo-calcium complexes that are either stable as amorphous structures or are removed in thermal processing. The incorporation of oleic acid, a long-chain unsaturated fatty acid, may have the effect of a surfactant or compatibilizer and improve the dispersion of the sulfur particles and minimize the agglomeration of the crystallites [54]. The structural simplification and higher purity observed in the XRD data can be attributed to the better performance of sulfur-based construction materials.