Water Pressures in Porous Asphalt

The New Zealand Transport Agency (NZTA) has recently experienced a small number of high profile new pavement failures where the surfacing was a Porous Asphalt (PA). A performance review provided a range of expert opinions as to the possible causes and potential solutions. An accelerated pavement testing programme was initiated at the Canterbury Accelerated Pavement Testing Indoor Facility (CAPTIF) to examine the opinions. One of the key industry opinions was that the PA contributed to the failure by allowing greater water pressures to build on the membrane seal under the PA layer. Small scale laboratory testing had shown that a failure mechanism was possible but the initial pressure conditions of the problem were unknown. Literature on Finite Element models for skid resistance suggested that the pressures should be substantially lower on PA surfaces. This paper presents the data from a novel use of piezometers to measure the water pressure occurring. The pressures were measured under various truck tyres on a chip sealed surface, on a PA surface and at the interface of the PA layer and membrane seal. The data shows that the water pressures on the PA surfaces and at the interface of the PA layer and membrane seal are significantly lower than those on the impermeable chip seal.


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  • Accession Number: 01880551
  • Record Type: Publication
  • ISBN: 9783030552350
  • Files: TRIS
  • Created Date: Apr 21 2023 9:51AM