University of Vermont Transportation Research Center

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A study evaluating the mechanical and hydraulic properties of several porous concrete pavement mix designs is presented. The objectives of the study were to: (1) quantify mechanical and hydraulic properties of select porous concrete pavement mix designs; (2) determine the effects of sample size on measured parameters; (3) evaluate the effects of winter surface applications (i.e. salt and sand) on hydraulic conductivity; (4) compare laboratory results with those obtained from the field; (5) measure surface infiltration capacity of porous concrete pavement installations; and, (6) determine the effects of plowing on surface infiltration capacity. Compressive strength results for the various mix designs ranged from about 6.2 MPa (910 psi) to 26.7 MPa (3,880 psi). Hydraulic conductivity test results yielded average values ranging from 0.18 cm/s (255 in/hr) to 1.22 cm/s (1,729 in/hr). Both compressive strength and hydraulic conductivity results were within the range of values reported in the literature. Compressive strength and hydraulic conductivity also showed a clear linear dependence with specimen density. Reduction in hydraulic conductivity of laboratory specimens after one winter surface application was found to be approximately 15%. Reduction in hydraulic conductivity after maximum clogging of laboratory specimens was found to be approximately 35%. Specimens that were vacuumed to reclaim hydraulic conductivity after clogging were on average restored to within 10% of the initial hydraulic conductivity. Preliminary surface infiltration capacity results showed that the porous concrete pavement facility recently built in Burlington, VT had adequate capacity for design storms in the region. Preliminary results from plowing simulation laboratory tests showed that plowing with no winter surface applications appeared to have an effect on the surface infiltration capacity of porous concrete specimens, reducing it somewhere between 6% and 15%. Using salt as a winter surface application appeared to yield similar results, reducing the surface infiltration capacity by 10%. Using a 2:1 sand to salt mixture had a more marked effect on surface infiltration capacity, leading to reductions of 96%.