就地热再生老化沥青混合料性能评价

Performance Evaluation of Aged Asphalt Mixture by Hot in-Place Recycling

老化沥青混合料的性能直接决定就地热再生工程的效果,本研究开展老化沥青混合料性能研究。对老化沥青混合料抽提筛分,发现沥青损失量较少,但针入度和延度衰退超过50%,粗集料明显细化。制备了3种混合料,路面回收旧料A、与旧料级配一致的新料B和与旧料初始级配一致的新料C,分别对其进行性能评价。动态模量试验表明沥青老化和级配衰减对沥青混合料黏弹性力学响应产生不利影响;A的冻融劈裂强度比仅为51.9%,表明抗水损害能力严重下降;A与C的高温稳定性接近,表明旧料高温稳定性保持稳定;A的抗弯拉强度、破坏应变、应变能密度分别是B的62.5%、32.3%和13.2%,表明旧料低温抗裂能力显著下降。沥青老化和级配衰变皆对就地热再生沥青混合料性能产生影响,尤其是水稳定性和低温抗裂性;但两因素的具体贡献比例有待进一步研究。

Performance significantly which has been aggregate are separated and of aged asphalt mixture influences the effect studied in submitted the paper. By extraction and sieving, for property inspection. It is found of hot in-place recycling the aged asphalt binder and that the loss of asphalt is limited, the degradation of binder＇s ductility and penetration are more than 50 percent and the coarse aggregates are refined. Three kinds of asphalt mixtures have been prepared in the study. A, aged asphalt mixture; B, new asphalt mixture （the same gradation with A）; C, new asphalt mixture （the same gradation with the initial construction） and their performance indicators are tested respectively. Dynamic modulus test indicates adverse effect of aged binder and degraded gradation on the viscos-elastic mechanical responses of asphalt mixture; the freeze and split test result of A is only 51.9 percent, which indicates the sharp reduction of water damage resistance of A; A is matching with C in light of high temperature performance which indicates the stable statues of high temperature performance~ the flexural tensile strength, failure strain and strain energy density of A are 62.5 percent, 32.3 percent and 13.2 percent of those of B which indicates sharp reduction of low temperature performance of A. Both aged binder and degraded aggregate gradation influence the properties of hot in-place recycled mixtures, especially for water damage and low temperature crack resistance, but the specific qualitative relationships need further investigation.