纤维对水泥-乳化沥青混合料性能的影响研究

Study on the Influence of Fiber on the Performance of Cement Emulsified Asphalt Mixture

水泥-乳化沥青混合料是以水泥-乳化沥青胶浆为胶结料和集料经强制冷拌形成的沥青混合料,制备和施工过程中无需加热,具有节能减排、施工方便等优势,符合公路行业对于碳排放和环保相关要求,但其综合路用性能逊色于同等条件下热拌沥青混合料。欲提高水泥-乳化沥青混合料的综合性能,在混合料中加入不同种类的纤维,并通过抗压强度试验、车辙试验、浸水马歇尔试验、低温弯曲试验、四点弯曲疲劳试验等试验进一步验证纤维对性能的增强效果。试验结果表明:纤维掺量和养生时间是影响其综合性能的关键因素,添加纤维后水泥-乳化沥青混合料的力学性能、高温性能、抗水损害性能、低温拉伸性能和疲劳耐久性均有一定程度地提高,这是由于纤维对水泥-乳化沥青胶浆的桥接和咬合作用;不同纤维种类对混合料综合性能的影响效果不同,在相同条件下聚酯纤维和水镁石纤维对水泥-乳化沥青混合料的抗压强度增强效果基本一致,但前者的动稳定度较前者大2495次/mm,而弯曲劲度模量小约140 MPa,即聚酯纤维对高温性能的贡献较大,而在低温性能方面的作用明显偏弱于水镁石纤维;从疲劳寿命次数看,水镁石纤维对混合料疲劳耐久性的贡献稍好于聚酯纤维,相对于水泥-乳化沥青混合料均得到大幅度提升,同时也减弱了对应力变化的敏感性。

Cement emulsified asphalt mixture is an asphalt mixture formed by forced cold mixing of cement emulsified asphalt mortar as cement and aggregates.It does not require heating during preparation and construction,and has the advantages of energy conservation,emission reduction,and convenient construction.It meets the requirements of the highway industry for carbon emissions and environmental protection,but its comprehensive road performance is inferior to that of hot mix asphalt mixture under the same conditions.In order to improve the comprehensive performance of cement emulsified asphalt mixture,different kinds of fibers are added to the mixture,and the strengthening effect of fibers on the performance is further verified through compressive strength test,rutting test,immersion Marshall test,low temperature creep test,four point bending fatigue test and other tests.The test results show that the fiber content and curing time are the key factors affecting the comprehensive performance of the cement emulsified asphalt mixture.The mechanical properties,high temperature properties,water damage resistance,low temperature tensile properties and fatigue durability of cement emulsified asphalt mixture after adding fiber are improved to a certain extent,which is due to the bridging and biting effects of fiber on the cement emulsified asphalt mortar.Different fiber types have different effects on the comprehensive performance of the mixture.Under the same conditions,polyester fiber and brucite fiber have basically the same effect on the compressive strength of cement emulsified asphalt mixture,but the dynamic stability of the former is 2495 times/mm larger than the former,while the flexural stiffness modulus is about 70 MPa smaller,that is,polyester fiber has a greater contribution to the high-temperature performance,while its role in the low-temperature performance is significantly weaker than that of brucite fiber.From the fatigue life times,the contribution of brucite fiber to the fatigue durability of the mixture is slightly better than that of polyester fiber,but compared with cement emulsified asphalt mixture,it has been greatly improved,and also weakened the sensitivity to stress changes.