Service Performance of Porous Asphalt Mixtures in Thailand: Laboratory and Full-Scale Field Tests

This article investigates the performance of porous asphalt (PA) mixtures and presents the first-ever full-scale test of a PA pavement overlay applied to a bridge deck on a motorway in Thailand, thus highlighting its engineering application for enhanced safety and durability. Phase 1 of the project ‘optimized’ the amount of Tafpack Super (TPS) additive and asphalt contents through tests and finite element analyses (FEA). The optimum amount of TPS additive was found to be 12% of the total weight of AC 60/70, which, together with an asphalt content of 4.5%, achieved an air void volume of 21.8%. Compared to a conventional AC 60/70 mixture, the ‘optimized’ mixture had a lower penetration value (−30%), higher softening point (+88%) and higher viscosity (+400%), thus meeting the requirements of the Japanese guidelines for PA. FEA also investigated the effect of Wheel Tracking loads on small slabs made with the ‘optimized’ PA mixture, and the results agreed well (within a 5% accuracy) with the test results. In Phase 2, the ‘optimized’ mixture was used to build 410 m of an actual motorway pavement (including a bridge deck overlay) to demonstrate the practical application of PA in busy road infrastructure in Southeast Asia. After six years of service, such PA pavement was shown to have higher skid resistance (+25%) and permeability (+3%) over conventional AC 60/70 mixtures currently used in road construction, underscoring the significance of PA pavements at enhancing road safety and performance in harsh climate conditions typical of the region.