## 3 Results and Discussion
### Durability Properties
However, when compared to CLAA-RBC90, CLAA-RBC50 has a higher mortar content and a lower Vg/Vm ratio, confirming what was stated in previous studies: The higher mortar content produces a denser cementitious matrix, contributing to the reduction in concrete permeation through the improvement of the matrix pore structure, thus contributing to better performance in terms of the durability of the structures. Considering this, the results obtained allowed for a comparison between the volume of lightweight aggregate per cubic meter and resistance to chloride ion penetration, as shown in Figure 19.  
It is evident that, except for the SCLC-SMR37 mix, the higher the volume of lightweight aggregates in the mix, the lower the chloride ion diffusion coefficient. The porosity of the aggregates does not have a significant direct relation with the resistance to chloride ion penetration. Thus, it can be concluded that matrix quality plays a larger role than lightweight aggregates in influencing durability, as the mix with the greatest susceptibility to chloride ion penetration corresponds to the one with the highest aggregate-to-mortar ratio (Vg/Vm) and the lowest mortar content. Table 7 presents a summary of the results obtained in this study. Figure 19: Relationship between coarse aggregate volume and chloride ion diffusion coefficient. SCLC-SMR37 presented the best overall performance, particularly in compressive strength, density, and resistance to chloride ion diffusion. SCLC-SBA90 presented competitive results in some parameters, such as compressive strength and apparent density. However, it was disregarded in the chloride ion diffusion analysis due to less satisfactory behaviour compared to SCLC-EC. Based on the overall balance of performance metrics, SCLC-SMR37 is indicated as the most efficient blend. The effect of aggregates on the properties of self-compacting concrete (SCC) has been extensively studied in the literature, with numerous international studies emphasizing the significant impact of lightweight aggregates on workability, strength, and durability. For example, [PERSON] et al. [8] demonstrated that the use of expanded clay aggregates in SCC notably enhanced its workability, achieving slump flow values comparable to those observed in the present study for SCLC-EC. Similarly, [PERSON] et al. [28] highlighted that aggregates with lower density, such as those derived from sugarcane bagasse ash (SBA), improve the flowability and passing ability of SCC, aligning well with the results for SCLC-SBA50 and SCLC-SBA90 in this study. Further studies by [PERSON] et al. [2] and [PERSON] et al. [21; 32] underscore the critical role of water absorption characteristics in lightweight aggregates, which directly influence viscosity and compressive strength. In this study, SCLC-SBA90, with its higher water absorption rate, exhibited a moderate increase in flow time (T500) compared to SCLC-EC. This observation is in line with findings by [PERSON] et al. [21], who reported that aggregates with higher water absorption led to increased viscosity, which in turn affected the overall workability of the concrete. When comparing the compressive strength results, this study's findings are consistent with those of [PERSON] and [PERSON] [24], who found that mixes with smaller lightweight aggregates demonstrated higher compressive strength gains due to a better interfacial bond between the aggregate and the cement paste. Our study, SCLC-SMR37, which showed the highest strength at 28 days, follows this trend, further emphasizing the importance of aggregate properties in enhancing concrete strength. Regarding chloride ion diffusion, the research by [PERSON] et al. [37] and [PERSON] and [PERSON] [23] highlights that aggregates with lower porosity and water absorption rates