Experimental Study On Clogging Mechanism Of Pervious Concrete

Pervious concrete is a kind of environmental protection product with penetrative pores made by special technology, and it retains enough strength and good air and water permeability. Pervious concrete has been widely applied in the road engineering, municipal engineering and landscape engineering, and has achieved good social, environmental and ecological benefits. Pervious concrete pavement has good drainage and noise reduction capability, and also has the ecological function of regulating surface temperature and humidity, and pervious concrete pavement has been widely used in many countries. Pervious concrete pile composite foundation has good anti-seismic performance. Pervious concrete pile can accelerate the consolidation of foundation and reduce after-construction settlement and liquefaction potential of foundation, and it has just been preliminary applied in engineering.Application of pervious concrete is mainly because pervious concrete has good air and water permeability while guaranteeing the required strength. However, once the pores clogged in pervious concrete, drainage capacity will be greatly decreased. For pervious concrete pavement, the surface runoff carries a great deal of sediment. The sediment along with water enter into pores in pervious concrete pavement, which causes pore clogging and reduce drainage function of pervious concrete pavement. Pervious concrete pile is mostly used to reinforce soft foundation with high groundwater level or water content, and piping most likely occurs in the soft foundation. When piping occurs, the pervious concrete pile plays a role of drainage consolidation. Seepage water carrying fine particle in soil can go through pores in pervious concrete pile, but part particles are stranded in pores. This leads to the pervious concrete pile loss the function of fast drainage consolidation.In order to reveal the meso-mechanism of pore clogging in pervious concrete, a pervious concrete clogging simulation test device was developed and a series of laboratory tests were performed. With this device, the evolution of permeability of pervious concrete was recorded in real time to discuss the process of pore clogging of pervious concrete, and the electrical conductivity was creatively introduced to characterize the pore clogging of pervious concrete. The developed test device was employed to simulate the sediment clogging in the pores of pervious concrete pavement under surface runoff and the clogging process of pervious concrete pile as piping occurrence. The tests reveal the mechanism of sediment entering, moving through, leaving and clogging in the pores of pervious concrete, and determine the effects of porosity of pervious concrete, sediment particle size, depth and velocity of surface runoff on the pore clogging of pervious concrete pavement, and the effects of soil gradation and size, compactness and thickness of the soil around pile on the pore clogging of pervious concrete pile. Based on the study of these key scientific issues, it will provide the scientific and effective basis the design and construction programs and parameter selection, maintenance and repair measures of pervious concrete, and it will also promote the research and development of the application of pervious concrete.