低温环境下沥青混凝土碾压结合层面性能试验研究

发布时间：2018-06-15 02:26

  本文选题：低温环境 + 碾压沥青混凝土　； 参考：《新疆农业大学》2014年硕士论文

【摘要】：水工沥青混凝土具有防渗性能好、适应变形能力强等特点，已广泛用于心墙坝中。目前，大部分沥青混凝土心墙都是在常温环境条件下进行碾压施工的。新疆寒冷地区施工工期短，在施工中也经常遇到机械故障等因素造成工期滞后，为满足来年防洪度汛高程需要适当延长施工工期，考虑在低温环境下进行碾压沥青混凝土的施工。而沥青混凝土心墙在低温环境下施工能否碾压密实、碾压层面温度过低时能否有效结合是一项急需解决的问题。 本文采用室内试验和现场试验相结合的研究方法，根据常温下的基础配合比确定了低温环境下的配合比；现场对低温环境下施工的心墙碾压沥青混凝土进行密度、孔隙率、渗透系数的测定，并钻取芯样进行力学性能试验，对比分析低温环境下由于沥青用量增加后沥青混凝土的物理、力学性能的变化；通过制作不同温度的下层料与上层热料结合的沥青混凝土试件，进行了结合面的劈裂抗拉试验、抗剪断试验、小梁弯曲试验、拉伸试验，分析不同结合面温度下抗拉性能的变化规律；通过室内试验量测上层热料摊铺后对不同温度下层料的加热效应，施工现场对碾压沥青混凝土结合面附近的温度变化进行观测，并对心墙越冬层的温度变化过程进行了监测。主要得到了以下结论： （1）试验用原材料各项技术指标均满足设计规范要求，低温环境下为提高沥青混凝土的施工性能，配合比参数的取值为：最大粒径为19mm、级配指数为0.38、填料用量为14%、沥青用量由6.6%提高到7.0%。 （2）现场检测表明低温环境下碾压沥青混凝土心墙的密度、孔隙率、渗透系数均能满足规范要求；由于沥青用量的增加使沥青混凝土的强度略有降低，适应变形能力增大，能够满足设计规范要求。 （3）对不同结合面温度试件进行试验后，劈裂抗拉强度、抗剪断强度、抗弯强度、拉伸强度均随结合面温度降低而呈下降趋势，结合面温度为30℃时与本体（一次成型试件）相比分别下降了10.6%、8.1%、4.5%、6.2%，下降幅度均较小，能够满足规范要求。 （4）结合面温度低于30℃时，试件断面较平整，，试件逐渐呈现脆性破坏，而结合面温度高于30℃时，试件断面粗糙不平，层间有大颗粒骨料相互嵌入，试件逐渐呈现延性破坏，表明随着结合面温度的降低对沥青混凝土的层间结合质量有一定影响。 （5）越冬期间利用电热毯加热心墙可起到保护心墙的作用，热砂加热法对越冬层加热效果显著。上层热料对下层沥青混凝土结合面加热效果明显，当160℃左右的热料摊铺到30℃的下层沥青混凝土后，通过热传递结合面以下10mm处温度可达到规范要求的70℃以上。 （6）试验表明：结合面温度从现行规范要求的70℃降低到30℃后，沥青混凝土能够碾压密实，并且结合面力学性能没有明显下降，碾压层面结合质量良好。
[Abstract]:Hydraulic asphalt concrete has been widely used in core dam because of its good impermeability and strong adaptability to deformation. At present, most asphalt concrete core walls are rolled under ambient conditions. In the cold area of Xinjiang, the construction period is short and the construction period is often delayed due to mechanical failure. In order to meet the flood control elevation in the coming year, it is necessary to extend the construction period appropriately. Considering the construction of roller compacted asphalt concrete in low temperature environment. Whether the asphalt concrete core wall can be compacted under low temperature and whether it can be effectively combined when the rolling layer temperature is too low is an urgent problem to be solved. In this paper, the combination of indoor test and field test is used to determine the mixture ratio at low temperature according to the basic mix ratio at room temperature, and the density and porosity of the core wall roller compacted asphalt concrete under the low temperature environment are carried out in the field. The permeability coefficient is measured and the core sample is drilled for mechanical performance test. The physical and mechanical properties of asphalt concrete under low temperature environment are compared and analyzed because of the increase of asphalt content. The split tensile test, shear test, trabecular bending test and tensile test of the bonding surface were carried out by making the asphalt concrete specimens with different temperatures of the lower layer and the upper hot material. The variation law of tensile performance at different bonding surface temperature is analyzed, and the temperature change near the interface of roller compacted asphalt concrete (RCC) is observed at the construction site through indoor test measuring the heating effect of the upper layer of hot material after spreading the lower layer material at different temperature. The temperature variation process of wintering layer of core wall was monitored. The main conclusions are as follows: (1) each technical index of raw materials for test meets the requirements of design code. In order to improve the construction performance of asphalt concrete under low temperature environment, The maximum particle size is 19mm, the gradation index is 0.38, the filler content is 14, and the asphalt content is increased from 6.6% to 7.0.The field test shows that the density and porosity of the RCC core wall under low temperature environment is higher than that of the RCC core wall. Due to the increase of asphalt content, the strength of asphalt concrete is slightly reduced, and the deformation ability is increased, which can meet the requirements of design code. The splitting tensile strength, shear strength, flexural strength and tensile strength decreased with the decrease of the temperature of the bonding surface. When the temperature of the bonding surface was 30 鈩

本文编号：2020149