多年冻土区冻融循环作用对沥青混合料弯拉性能的影响

发布时间：2018-01-19 00:27

本文关键词： 道路工程冻融循环试验弯拉性能损伤率模型细微观空隙结构　出处：《公路工程》2017年01期 　论文类型：期刊论文

【摘要】：为准确评价冻融循环作用对高原寒冷地区沥青混合料弯拉性能和细微观结构的损伤机理,针对北方寒冷地区沥青路面在荷载、低温、水冻融循环作用下剩余弯拉强度和疲劳寿命进行研究,制定了适宜的冻融循环试验方案,建立了不同沥青结合料沥青混合料的空隙率、弯拉强度(弯拉应变)、劈裂强度和疲劳寿命在不同冻融循环作用次数下的衰变规律,基于工业CT无损检测分析技术,获得了不同冻融循环次数下四种沥青混合料细观空隙结构变化特征,研究了冻融循环作用对沥青混合料平均空隙直径、空隙轮廓分维数的影响规律,分析给出了冻融循环作用下沥青混合料弯拉性能的损失率计算模型。结果表明:沥青混合料的弯拉强度、最大弯拉应变、劈裂强度、疲劳寿命随冻融循环次数的增加呈减小趋势,经历25次冻融循环后弯拉性能和疲劳寿命衰减趋于平缓。沥青混合料受冻融循环作用后弯拉强度和抗疲劳性能衰变规律符合logistics曲线模型;随着冻融循环次数增大,沥青混合料内部平均空隙直径增大,空隙轮廓分维数减小,平均空隙直径与沥青混合料弯拉性能之间的线性拟合关系良好;使用改性沥青具有维持冻融循环作用下沥青混合料内部空隙直径、空隙轮廓分维数变化不大的作用,在高原寒冷地区建议优先选用SBS或SBR改性沥青。
[Abstract]:In order to evaluate accurately the damage mechanism of freeze-thaw cycle on the bending and tensile properties and fine microstructure of asphalt mixture in the cold region of plateau, aiming at the load and low temperature of asphalt pavement in the cold area of northern China. The residual flexural tensile strength and fatigue life under the action of water freeze-thaw cycle were studied, the suitable test scheme of freeze-thaw cycle was established, and the void ratio and bending tensile strength (flexural strain) of different asphalt binder asphalt mixture were established. The decays of splitting strength and fatigue life under different cycles of freeze-thaw cycles are based on the nondestructive testing technique of industrial CT. The variation characteristics of meso-void structure of four kinds of asphalt mixture under different freeze-thaw cycles were obtained. The influence of freeze-thaw cycle on the average void diameter and the fractal dimension of void profile of asphalt mixture was studied. The loss rate model of asphalt mixture under freeze-thaw cycle is analyzed. The results show that the flexural tensile strength, maximum flexural strain and splitting strength of asphalt mixture are calculated. The fatigue life decreases with the increase of freeze-thaw cycles. After 25 freeze-thaw cycles, the bending and tensile properties and fatigue life decay of asphalt mixture after freeze-thaw cycles tend to be gentle. The decay law of flexural tensile strength and fatigue resistance of asphalt mixture under freeze-thaw cycle accords with the logistics curve model. With the increase of freeze-thaw cycles, the average void diameter of asphalt mixture increases, the fractal dimension of void profile decreases, and the linear fitting relationship between the average void diameter and the bending and tensile properties of asphalt mixture is good. The modified asphalt has the function of maintaining the internal void diameter and the fractal dimension of the void profile of asphalt mixture under the action of freeze-thaw cycle. It is suggested that SBS or SBR modified asphalt should be preferred in the cold area of plateau.
【作者单位】：济南工程职业技术学院;
【分类号】：U414
【正文快照】： 0引言近年来,我国高速公路有向青藏高原寒冷地区年平均气温低、昼夜温差大、冻融循环频繁,对沥青路面力学性能、路用性能及耐久性能影响明显。以青藏公路大规模建设为序幕,国内相继开展了冻融循环对沥青路面耐久性的影响方面的研究。党松阳研究了橡胶粉改性沥青对沥青混合料抗

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