This paper discusses the construction and early performance of a perviousconcrete test cell at the MnROAD facility. The cell is subjected to daily loading of an 80-Kip 5-axle semi-trailer, two times a day, four days a week and 102-Kip 5-axle semi-trailer twice a day, one day a week. Performance was evaluated by comparing Falling Weight Deflectometer (FWD) deflection basins to those of normal concrete pavements of similar thickness design. Stress-strain response of the pavement system was computed from dynamic strain gauge data. Temperatures and freeze-thaw cycles at various pavement depths where monitored. An in-situ method for measuring time rate of flow was developed. Petrographic analysis reveled differences in porosity between the surface and bottom layers as well as drying shrinkage cracking. Normal sanding and salting operations during the winter do not appear to have impacted the pore structure within the pervious concrete after three years of service. Spalling and raveling were prevalent at the tooled joints and occurred in sections where the surface could have prematurely dried due to overworking. The test cell driveway showed superficial wear near the joints after its first season in service. Large 12x12 ft rectangularblock cracking was observed after 2 ½ years as well as reflective cracking propagated from joints of the surrounding curb. Critical parameters including time rate of flow, raveling, and cracking will continue to be monitored.
Abstract