模拟温压实的常温再生混合料二次成型温度研究

Laboratory Secondary Forming Temperature of Cold Recycled Mixture by Simulating Field Secondary Thermal Compaction

摘要:

为使室内常温再生沥青混合料设计真实反映现场实际工况，结合4条高速常温再生实体工程，实测了上覆热拌沥青混合料（HMA）施工过程中常温再生层中不同深度处的温度，分析了不同常温再生层厚度、不同上覆HMA厚度以及不同气候施工对常温再生层温度场的影响，建立了常温再生层不同深度处的温度预估方程；同时测试了不同施工大气温度下常温再生层芯样及室内试件的体积参数和力学性能。结果表明：上覆HMA摊铺过程中，再生层内部温度变化受施工环境影响较大；施工大气温度以及室内二次成型温度对常温再生混合料空隙率、抗弯拉强度、抗剪强度及断裂功影响显著，施工大气温度为30℃左右时，相比于0℃左右，空隙率降低约25%，抗弯拉强度、抗剪强度及断裂功分别至少提升45%、66%、77%；室内二次击实温度为80℃时，相比于40℃，空隙率降低约20%，抗弯拉强度、抗剪强度及断裂功分别至少提升42%、35%、80%；室内常温再生混合料设计时，应考虑二次成型温度的影响，以模拟现场再生层因内部温度变化而对混合料性能产生的影响。

Abstract:

In order to make the design of cold recycled mixture in the laboratory truly reflect the actual working conditions in the field， this paper measured the process of temperature variation in the cold recycled layer during the construction of the hot-mix asphalt（HMA） mixture above the cold recycled layer. Based on the measured temperature， the effect of the cold recycled layer thickness， the overlying hot-mix layer thickness， and construction seasons were analyzed. The temperature prediction equations in the cold recycled layer were established. Simultaneously， the volumetric parameters and mechanical strength of the core samples after the secondary thermal compaction of the cold recycled layer at different construction temperatures were tested. The results show that during the paving process of the HMA， the temperature change in the cold recycled layer is greatly affected by the construction environment. The void ratio， flexural tensile strength， shear strength， and fracture work of cold recycled mixture are significantly affected by the construction temperature and laboratory secondary forming temperature. Compared with 0 ℃， when the construction temperature is about 30 ℃， the void ratio is reduced by about 25%， while the flexural tensile strength， shear strength， and fracture work are increased by at least 45%， 66%， and 77% respectively. Compared with 40 ℃， when the laboratory secondary compaction temperature is 80 ℃， the void ratio decreases by about 20%， while the flexural tensile strength， shear strength， and fracture work increase by at least 42%， 35%， and 80% respectively. The influence of secondary forming temperature should be considered in the design of cold recycled mixture to simulate the effect of the cold recycled layer on the performance due to the change of internal temperature.