Laboratory Characterization of Clogging Potential of Porous Asphalt Mixtures

Abstract

It is of practical significance to be able to evaluate the clogging potential of a porous asphalt mix in the laboratory during the mix design phase. This paper presents a laboratory evaluation procedure to assess the clogging potential of porous asphalt materials, and identify the mix properties that influence the clogging potential of a porous asphalt mixture. Eleven different porous mix designs were studied, with their top aggregate sizes varying from 9.5 to 19 mm, covering a porosity range of 10–28%. The procedure consists of a clogging treatment to introduce a selected clogging material into a test specimen in stages, with permeability measurements made after each stage of clogging. From the test results, two clogging potential indicators were defined: a clogging potential factor β, and the number of clogging cycles to reach the final state of fully clogged condition N_c. The effects of the following six mix properties on clogging potential of the mixes were studied: initial porosity P₀, initial permeability coefficient k₀, top aggregate size D_T, coefficient of uniformity C_u, coefficient of curvature C_c, and coefficient of infiltration C_i. Statistical analyses were performed and it was found that the two clogging potential indicators were significantly influenced by k₀, P₀, and D_T. Statistically significant predictive models for β and N_c were developed with these three mix properties as the predictor variables. The predictive models can serve to provide useful guidance for pavement engineers in the design of porous asphalt mixtures.