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压实沥青混合料试件的密度测量一直受到道路工作者的关注。由于水中重法简单、方便,在I型密级配沥青混合料的设计、施工和质量控制中允许采用。采用水中重法和表干法对我国沥青混凝土路面上常用的3种密级配沥青混合料,共计38个试件测量其视密度和表干毛体积密度。利用统计工具SPSS对两种方法测量的密度进行了统计分析。统计结果表明:水中重法和表干法测量的密度变异性,统计学上没有差异,但两种方法测量的密度值有显著差异。38个试件的平均视密度比平均表干密度大0.028 89 g/cm3,由此计算的沥青混合料试件空隙率相差达1.1%。两种方法计算的密度差或空隙率差值与试件的吸水率成正比例关系。建议在沥青混合料配合比设计中,不再使用水中重法测量的视密度代替表干法的毛体积密度。在工程施工过程和质量检测中,只有当试件或芯样吸水率极小时或不吸水时,水中重法方能代替表干法测量试件或芯样的毛体积密度。
Density measurement of compacted asphalt mixture specimens has always been the concern of road workers. As the heavy water method is simple and convenient, I type dense graded asphalt mixture design, construction and quality control allowed. The water density method and surface dry method were used to measure the apparent densities and surface dry bulk densities of three closely graded asphalt mixtures commonly used in China’s asphalt concrete pavement. Using the statistical tool SPSS, the density of the two methods was statistically analyzed. The statistical results show that there is no statistical difference in the density variability measured by both water method and surface dry method, but the density values measured by the two methods have significant differences. The average apparent density of 38 samples was 0.02889 g / cm3 higher than the average dry density, and the calculated void fraction of asphalt mixture samples was 1.1%. The difference in density or porosity calculated by the two methods is directly proportional to the water absorption of the specimen. Proposed mix design in the asphalt mixture, the water is no longer measured using the apparent density instead of surface dry method of gross bulk density. In the construction process and quality inspection, only when the sample or core sample with little or no water absorption, the water method can replace the surface dry method to test the bulk density of the sample or core sample.