Evaluation of functional characteristics of laboratory mix design of porous pavement materials

Porous pavements are designed and constructed today to provide one or more of the following functional benefits: lower traffic noise, improved wet-weather driving safety, lower stormwater peak load, and replenishment of groundwater supplies. However, depending on the mix design and material properties of a porous pavement, not all these benefits can be achieved fully by the porous pavement. The factors that affect such functional benefits include the porosity, the properties of binder and aggregates, and the binder content and aggregate gradation of the porous mixture. Currently no agencies have specified any laboratory test procedure for pavement engineers to evaluate the functional characteristics during the mix design phase. Such laboratory procedures are useful in practice for porous pavement design. This study demonstrates that a set of laboratory tests based on currently available equipment and methods, along with related functional assessment analysis, can be performed to meet the purpose. The following laboratory tests on the design mix are proposed in this study: (i) Permeability test. (ii) 3-dimensional scanning of surface texture, (iii) Skid resistance test, and (iv) Sound absorption test. The test data may then be used for drainage capacity analysis, wet-weather skid resistance assessment, and tire-pavement noise analysis. The proposed laboratory test procedures are illustrated using two porous pavement materials. The test results show that practically useful information on functional characteristics of a design porous mix can be obtained using the proposed procedures.