ICPI Interlock Design Issue 3 2018

 By David Smith ENGINEER’S view InterlockDesign.org 15 SUMMER 2018 ® esign interloc Faster Edge Restraints for Permeable Pavement in Pedestrian & Residential Driveways Metal edge restraints replaced concrete in this residential driveway. P ermeable interlocking concrete pave- ments (PICP) typically use cast-in-place concrete curbs for parking lot, alley and street applications. Some years ago, edge restraints made from metal or plastic were developed for PICP pedestrian and residential driveways. Time has demon- strated good performance of these faster- installation edge restraints that incorporate geogrids for these light-duty applications. Sieve Size Percent Passing 1 1/2 in. (37.5 mm) 100 1 in. (25 mm) 95 to 100 1/2 in. (12.5 mm) 25 to 60 No. 4 (4.75 mm) 0 to 10 No. 8 (2.36 mm) 0 to 5 Start with a Firm Foundation PICP for pedestrian and driveway applications consists of a base foundation or reservoir of crushed, washed, open- graded aggregate to store and infiltrate water. Depending on quarry sources, aggregate sizes generally close or within the ASTM No. 57 gradation are adequate. The washed ASTM No. 57 gradation follows: Photo courtesy of Fred Adams Paving, Inc.