University of California Pavement Research Center, Department of Civil and Environmental Engineering, One Shields Avenue, Ghausi Hall, University of California, Davis, CA 95616, USA.
J Environ Manage. 2013 Nov 15;129:164-72. doi: 10.1016/j.jenvman.2013.07.005. Epub 2013 Aug 3.
In this study a new procedure is developed to obtain core samples from field sections to assess clogging mechanisms of open graded friction course (OGFC) pavements using X-ray computed tomography (CT) imaging. The approach compared X-ray computed tomography (CT) images taken before and after: (1) rainfall simulations without trafficking to investigate particle-related clogging and (2) full-scale accelerated pavement rutting tests (APT) to investigate deformation related clogging of OGFC layers. Rainfall simulations were performed with runoff water of known total suspended solids (TSS) and particle size distributions (PSDs). Full-scale accelerated rutting tests were performed under controlled temperature and loads. Both investigations were performed for three different OGFC pavements with different layer thicknesses and mix types. The clogging of rutting test sections were also evaluated by comparing the surface permeability measurements performed before and after APT testing. The results of X-ray CT image processing revealed a significant reduction in air-void content of core samples after APT rutting tests. The highest air-void reduction was concentrated at the bottom of the OGFC layers. Permeability measurements also showed a 40%-90% reduction in permeability after APT trafficking. X-ray CT image processing of core samples tested under simulated rainfall showed that air void content reduction is concentrated in the lower part (2-6 mm from the bottom) of the OGFC layers as a result of particle accumulation. Small changes in air void contents were observed in the upper part of the OGFC layers (10-15 mm) while these reductions in air void contents were not significant to cause surface overflow and hence it is expected that the tested OGFC pavements will have sufficient permeability to infiltrate water during most average storm events.
本研究开发了一种新的方法，从现场取芯以评估使用 X 射线计算机断层扫描 (CT) 成像的开级配磨耗层 (OGFC) 路面的堵塞机制。该方法比较了在以下情况下进行 X 射线计算机断层扫描 (CT) 成像前后的结果：(1) 没有交通量的降雨模拟以研究颗粒相关的堵塞，以及 (2) 全尺寸加速路面车辙试验 (APT) 以研究 OGFC 层的变形相关堵塞。降雨模拟使用具有已知总悬浮固体 (TSS) 和颗粒尺寸分布 (PSD) 的径流水进行。全尺寸加速车辙试验在受控温度和荷载下进行。这两种研究均针对具有不同层厚和混合类型的三种不同 OGFC 路面进行。还通过比较 APT 测试前后进行的表面渗透率测量来评估车辙测试部分的堵塞情况。X 射线 CT 图像处理的结果表明，APT 车辙试验后芯样的空隙率显著降低。空隙率降低最集中在 OGFC 层的底部。渗透率测量也显示 APT 交通后的渗透率降低了 40%-90%。在模拟降雨下测试的芯样的 X 射线 CT 图像处理表明，由于颗粒堆积，空隙率降低主要集中在 OGFC 层的下部（距底部 2-6mm）。OGFC 层上部的空隙率变化很小（10-15mm），而这些空隙率的降低不足以导致表面溢出，因此预计所测试的 OGFC 路面在大多数平均暴雨事件中具有足够的渗透能力来渗透水。
