공시체 구속 상태에서 정하중 시험에 의한 SMA 혼합물의 소성변형 저항성평가 가능성

Feasibility of Estimating Rut Resistance of SMA Mixture by Static Loading Test Using Confined Specimen

Abstract

It is well-known fact that the stone-mastic asphalt (SMA) mixture has shown superior rut resistance, compared with the dense-graded asphalt (DGA) mixture in highway pavements. However, the SMA is measured to be inferior to DGA mixes when tested by well-known high-temperature test methods, such as the wheel tracking (WT), asphalt pavement analyzer, the Marshall Stability and Kim Test. Therefore, this study examined the reasons why it was measured to be inferior, and devised a potential procedure by which the superiority of SMA could be measured at $60^{\circ}C$. The strength against deformation ($S_D$), which was known to show very high correlation with WT results for DGA mixes, was measured by the Kim Test on the specimen confined in the compacted mold. In standard Kim Test, which used the specimen without confinement, the DGA was measured to show higher $S_D$ than the SMA. But by confining specimen, it was found that the $S_D$ of SMA was measured to be higher than that of DGA. Therefore, the confined static test protocol devised in this study was found to be feasible for evaluating rut resistance of SMA mix.

Fig. 1 Illustration of (a) WT equipment and (b) a curve from a WT test

Fig. 2 Kim Test procedure on 100㎜ specimen without lateral confinement

Fig. 3 Kim Test on 100㎜ specimen confined MarshallMold

Fig. 4 Comparison of P-v curves of an unconfined Kim in test and a confined Kim test

Fig. 5 Relation of WT rut depth and S_D

Fig. 6 Illustration of body confinements for specimen diameter of (a) 150㎜ and (b) 100㎜

Fig. 7 Two larger-size specimens; (a) 150㎜ diameter and (b) 312 hexagon specimen (Kim et al., 2008; Lee et al., 2013)

Fig. 8 Load and deformation curves from Kim Test on specimens confined in Marshall mold

Fig. 9 SD trends by v from confined Kim Test for SMA and DGA

Fig. 10 SD ratio of SMA over DGA by v

Fig. 11 Vertical deformation (v) by pressure (S_D) of SMA and DGA

Table 1 WT test results for SMA and DGA mixtures with 13㎜ aggregate

Table 2 S_D of SMA and DGA mixtures with 13㎜ aggregate (100㎜ diameter specimen)

Table 3 S_D for SMA measured from larger-size specimens (Lee et al., 2013)

Table 4 Required load to induce each vertical deformation (v), S_D and S_D ratio