DEVELOPMENT OF AN ASCE STANDARD FOR PERMEABLE INTERLOCKING CONCRETE PAVEMENT

This paper describes the technical development of the emerging ASCE standard for permeable
interlocking concrete pavement or PICP. The draft standard notes key design elements which include high strength, impermeable concrete units for the surface that meet American Society for Testing Materials or Canadian Standards Association standards. When installed, the joints between units are filled with permeable aggregate. The units are placed over an open-graded aggregate bedding course which rests on an open-graded aggregate base and subbase for water storage and structural support. While common to all permeable pavements, the document provides a design flow chart for structural and hydrologic design and outlines three commonly used infiltration approaches determined by site and subgrade conditions, as well as designs for sloped subgrades. The draft standard addresses structural design for supporting traffic by modifying conventional flexible pavement design methodology from the American Association of State Highway and Transportation Officials.
The draft standard considers many design variables and how to address them. It resolves a key design consideration common to all permeable pavements; the dichotomy between not compacting the soil subgrade for infiltration and compacting for enhanced structural support especially in saturated conditions. Besides guide construction specifications, construction and maintenance guidelines are provided via checklists. A key tool for assessing surface infiltration and subsequent vacuum cleaning is adoption of an ASTM surface infiltration test for pervious concrete which has been successfully used for porous asphalt and PICP.