Rao Yunkang, Fu Haiying, Yang Tao, Chen Huailin, Zhang Zhe, Ding Haojiang
Department of Geotechnical Engineering, School of Civil Engineering, Southwest Jiaotong University, No.111, North Section 1, Erhuan Road, Chengdu, 610031, Sichuan, China.
China Railway Eryuan Engineering Group Co. Ltd, Chengdu, 610031, China.
Sci Rep. 2022 Jun 3;12(1):9258. doi: 10.1038/s41598-022-13483-9.
Pervious concrete (PC) pavement has been widely accepted as a green infrastructure but is prone to clogging. This study comparatively investigated sand and clay clogging mechanisms of PC and vertical sediment distributions of sand-clogged and clay-clogged PCs. Clay and three sizes of sand were used to clog PC under two exposure methods (no drying and drying). X-ray computed tomography (CT) was used to scan the clogged samples before and after 30 pressure washing cycles. The clogged permeability and permeability after each washing cycle were measured. The clogging patterns of sand depend mainly on sand particle sizes relative to PC pore sizes. The applied fine sand, coarse sand, and medium sand cause easy-passing clogging, surface clogging, and full-depth clogging, respectively. After clay clogging, more than 77% of the total retained clay occurs within the vertical region 24-72 mm below the sample surface; the most clogging (the lowest-permeability layer) occurs at a depth of approximately 48 mm. The dried clay retained within the region 40-120 mm below the surface (especially within the lowest-permeability layer) is hard to wash away because the drying process increases the cohesion of internal clay particles and clay adhesion to the rough, tortuous pore wall of PC. The clogged normalized permeability of 0.154 and permeability recovery ratio of 4.91% in dried clay-clogged samples are lowest among all the samples. However, pressure washing readily washes away the retained undried clay. Accordingly, it is recommended that pressure washing is used to eliminate the clogging effect of dried clay before hot, sunny exposure conditions dry the retained clay. This study provides evidence for developing effective pavement maintenance strategies.
透水混凝土（PC）路面作为一种绿色基础设施已被广泛接受，但容易堵塞。本研究比较研究了PC的砂和粘土堵塞机制以及砂堵塞和粘土堵塞的PC的垂直沉积物分布。使用粘土和三种不同粒径的砂，通过两种暴露方法（不干燥和干燥）堵塞PC。在30次压力冲洗循环前后，使用X射线计算机断层扫描（CT）对堵塞的样品进行扫描。测量每次冲洗循环后的堵塞渗透率和渗透率。砂的堵塞模式主要取决于砂粒尺寸与PC孔隙尺寸的相对关系。施加的细砂、粗砂和中砂分别导致易通过堵塞、表面堵塞和全深度堵塞。粘土堵塞后，总保留粘土的77%以上出现在样品表面以下24-72毫米的垂直区域内；最严重的堵塞（渗透率最低的层）发生在约48毫米的深度处。表面以下40-120毫米区域内（特别是在渗透率最低的层内）保留的干燥粘土很难被冲走，因为干燥过程增加了内部粘土颗粒的凝聚力以及粘土与PC粗糙、曲折孔隙壁的附着力。在所有样品中，干燥粘土堵塞样品的堵塞归一化渗透率为0.154，渗透率恢复率为4.91%，是最低的。然而，压力冲洗很容易冲走保留的未干燥粘土。因此，建议在炎热、阳光充足的暴露条件使保留的粘土干燥之前，使用压力冲洗来消除干燥粘土的堵塞效应。本研究为制定有效的路面维护策略提供了依据。
