## 4 Permanent Deformation (PD)  
Figure 8 illustrates the behavior of the studied material concerning PD, comparing the results obtained in specimens with 0 and 28 days of curing. For mixtures with 0 days of curing the highest permanent deformationsrecorded were observed in tests whose stress pairs are 120/240 kPa and 80/240 kPa, confining versus deviator, respectively, reaching values close to 7 mm at the endof the tests. The pair 80/160 kPa presented considerably smaller deformations than the pairs 120/240 kPa and 80/240 kPa. The smallest deformations were foundin the 80/80 kPa e 120/120 kPa tests. The variations in PD increase with the rise in deviator stress and the growth of the \(\sigma\)d/\(\sigma\)3 ratio (KPa/KPa). It is also evident that PD decreases with increasing confining stress and that the higher the \(\sigma\)d/\(\sigma\)3 ratio, the greater the permanent deformation. This behavior indicactsthat the permanent deformations magnitude is related tothe ratio among \(\sigma\)d/\(\sigma\)3 in a directly proportional relation. The mixtures with 28 days of curing also the highest permanent deformationsrecorded were observed in tests whose stress pairs are 120/240 kPa and 80/240 (\(\sigma\)d/\(\sigma\)3, KPa/KPa). however, reaching values close to 4 mm at the endof the tests, i.e., there was a reduction of up to 3 mm in the PD behavior after 28 days of curing. Figure 8: Accumulated permanent deformation at 0D and 28D of curing. Moreover, it can be observed that in some instances, mixtures with 0 days of curing accumulate deformations close to those at 28 days of curing, but for different \(\sigma\)d/\(\sigma\)3 ratios, with a \(\sigma\)d/\(\sigma\)3 ratio of 1 for 0 days and a \(\sigma\)d/\(\sigma\)3 ratio of 2 for 28 days, in the stress pairs 120/120 (\(\sigma\)d/\(\sigma\)3, KPa/KPa) and 80/240 (\(\sigma\)d/\(\sigma\)3, KPa/KPa), respectively. However, none of the tests conducted with 0 days of curing showed a lower deformation rate than the samples with 28 days. Observing the increase rate graph in PD by the accumulative vertical deformation it can be seenthat all of them tests to type B behavior accordingto the parameters of Dawson and Wellner [68] and Werkmeister [69]. The mixtures with 28 days of curing, the 80/80 kPa and 120/120 KPa pair reached the accommodation (behavior A), as it possible to see in Figure 9b, for the a \(\sigma\)d/\(\sigma\)3 ratio of 1. The other pairs present behavior B. However, some stress combinations show intermediate behavior, such as the stress pairs 40/120 (\(\sigma\)d/\(\sigma\)3, KPa/KPa) and 80/160 (\(\sigma\)d/\(\sigma\)3, KPa/KPa) at 28 days, with a gradual reduction in the deformation rate over the tests. On the other hand, samples with \(\sigma\)d/\(\sigma\)3 ratios of 2 and 3, in the stress pairs 120/240 (\(\sigma\)d/\(\sigma\)3, KPa/KPa) and 80/240 (\(\sigma\)d/\(\sigma\)3, KPa/KPa), respectively, resulted in high permanent deformation rates at the end of the tests. This suggests that the material may not have reached stability, only a tendency towards accommodation [82], after 150,000 cycles, due to the rate of increase reaching values of \(1\times 10^{-6}\) to \(1\times 10^{-7}\) mm per cycle. In practice, mixtures of RAP mixed with natural aggregates can be acceptable for use in the base of a pavement, provided that the accumulated deformation remains minimal  
Figure 9: Permanent strain rate per accumulated strain. (**a**) Tests with 0-day curing time. (**b**) Tests with 28-day curing time. (see the lower curves in Figure 8), as also corroborated by the studies of [41], who analyzed samples with 60% RAP and 40% VA). However, higher and non-stabilized deformation behaviors (such as the upper curves in Figure 8) suggest that the material may be subject to excessive stresses for this specific application, being more suitable for use in lower pavement layers where stresses are lower.