## 3 Results and Discussion
### Influence of the Type of Aggregate on the Chloride Penetration Resistance
Then, the re-saturation of LWA and their effective participation in chloride penetration is more prone to occur in high w/b matrixes with coarser microstructure and less protection capacity. Therefore, the differences between LWAC with more porous LWA and NWC were less noticeable in low w/b concrete, up to w/b of 0.45 (Figure 11b), but relevant in concrete with a w/b of 0.55. Thus, the influence of the type of aggregate depended on the exposure conditions and paste composition. Nevertheless, LWAC with denser LWA performed similarly to NWC, both in the IT and the WDT, regardless of the concrete composition. A slightly better behaviour of these concretes was even observed, for high w/b concrete. One reason may be attributed to the improved interfacial transition zone (ITZ) usually observed in LWAC [55; 75]. The \(K_{cr}\) of concrete with different types of aggregates is presented in Figure 12, for the IT and the WDT. The \(C_{s}\) tended to be higher in LWAC with more porous LWA than in NWC and LWAC with denser aggregates (Stalite), both in the IT and the WDT (Table 5). The same behaviour was reported by other authors [4; 5; 18; 26; 39]. This is essentially attributed to the saturation of LWA at the concrete surface, retaining chlorides [76]. This contributed to a higher chloride penetration, increasing the \(K_{cr}\) in LWAC with more porous LWA. For the same reasons mentioned above, this difference was more relevant in high w/b concrete. In general, the increase of \(D_{d}\), combined with the higher \(C_{s}\), led to a more significant influence of the type of aggregate on the \(K_{cr}\), at least for short-term exposure tests, in which the influence of the concrete surface is more relevant. The lower value of \(K_{cr}\) in LWAC with Leca and a w/b of 0.35 is explained by the unexpectedly low value of \(C_{s}\) in this concrete (Table 5). In this case, the self-dissection could have partly emptied LWA, reducing both the \(D_{d}\) and the \(C_{s}\). Regarding LWAC with denser LWA, the influence on the \(D_{cl}\) and on the \(C_{s}\) was not significant and the \(K_{cr}\) was similar to that of NWC, regardless of the w/b. The lowest values of the \(K_{cr,WDT}\) in LWAC with denser LWA and high w/b were motivated by the lowest \(D_{cl,WDT}\) obtained in this concrete. A reasonable trend was obtained between the \(D_{cl,IT}\) and the \(D_{cl,RCMT}\) (Figure 13), showing that the RCMT was able to adequately distinguish the \(D_{cl}\) of concretes with different types of aggregate under long-term immersion exposure conditions. This is explained by the fact that both tests were performed in saturated exposure conditions. However, for the mentioned reasons, the greater participation of porous LWA in high w/b concrete under IT reduced the correlation between tests. These differences were accentuated in the WDT, being justified, as mentioned, by the different exposure conditions that may promote a distinct participation of LWA near the concrete surface, affecting chloride penetration. As previously mentioned, R2 would be significantly higher, if regressions were not forced to cross the origin, but the physical meaning of the analysis would be distorted.