厂拌热再生沥青混合料低温抗裂与水稳定性研究

Low Temperature Anti-cracking Performance and Water Stability of Hot Recycled Asphalt Mixture from Central Plant Mixing

基于室内试验测定了回收沥青面层材料中旧沥青、旧集料,新加沥青、新加集料及再生剂的各项性能指标;通过马歇尔试验确定了不同类型再生沥青混合料(AC-16C和AC-13)的最佳沥青用量。通过低温小梁弯曲试验和冻融劈裂试验,分析了不同旧料掺配比例、不同旧料类型、是否添加再生剂及二次老化前后混合料的低温抗裂性与水稳定性。结果表明:再生沥青混合料随旧料掺配比例的增加低温性能逐渐变差;短期水损害对其稳定性影响不大,但抵抗长期水损破坏的能力却大幅下降;旧料类型对再生沥青混合料性能的影响关联不大;添加7%~9%掺量的再生剂对其低温抗裂与水稳定性能的改善效果优于10%掺配比的再生混合料,基本接近新拌沥青混合料;二次老化后再生沥青混合料低温抗裂性能下降较快,虽仍可抵御短期水损害,但对其长期水稳定性影响较大,建议添加一定比例的再生剂。AC-13型再生沥青混合料抵抗低温开裂与水损破坏的能力相比于AC-16C型级配更强,更适合做上面层。

Through indoor experiments,the indicators of the old asphalt and old aggregate in RAP,the added asphalt,the added aggregate and the regeneration agent were detected.Marshall Test was applied to determine the optimum asphalt content of different types of hot recycled asphalt mixtures（AC-13 and AC-16C）from central plant mixing.Additionally,trabecular low-temperature bending test and freeze-thaw splitting test were used to analyze the low temperature anti-cracking performance and water stability of the recycled asphalt mixtures with different RAP percentages,different RAP types,as well as different conditions before and after second aging and adding recycling agent or not.The results show that with the increase of RAP,the low temperature properties of recycled asphalt mixture gradually decrease.The short-term water damage has little effect on its stability,but the long-term ability to resist water damage drops sharply.The influence of the old material type on the performance of the recycled asphalt mixture is not very relative.The improvement effect of the low temperature crack resistance and water stability of the mixture adding 7％～9％recycling agent are better than those of the 10％mixing ratio recycled mixture,which is basically close to the new asphalt mixture.The low temperature anti-cracking performance of the recycled asphalt mixture decreases rapidly after second aging.Though the mixture can still withstand short-term water damage,it has greater impact on the long-term water stability.Therefore,adding some proportion of the regeneration agent is suggested.Compared with AC-16C type,AC-13 type recycled asphalt mixture has better ability to resist the low temperature cracking and water damage,which is more suitable for the top layer.