Practical laboratory ageing method for porous asphalt

<p align="LEFT"> </p> <p align="LEFT">During the mix design phase of porous asphalt (PA) pavements, it is imperative to know the PA properties after field ageing. This will help to optimize pavement performance and to increase the confidence level of the pavement design. A study was initiated to develop a laboratory ageing procedure for PA mixtures. This procedure should be able to mimic 10 years of field ageing within 10 days in a laboratory using only standard lab equipment. Conventional empirical and sophisticated fundamental rheological tests (penetration, softening point ring and ball, DSR), chemical tests (FTIR) and adhesion tests (Wilhelmy plate) were conducted on binders recovered from field cores and on binders recovered from specimens that were subjected to laboratory ageing. Finally two ageing procedures were developed: one for the mortar in PA and one for the loose PA mix. To accomplish the same ageing of the bitumen as in 10 year period in the field, the mortar has to be heated in an oven for 2 hours at 165&deg;C and then be placed in a PAV at 90&deg;C for 7 days under air pressure of 2.1 MPa. The loose PA mix has to be heated for 44 hours at 135&ordm;C to accomplish the same degree of ageing. In this paper the research program is discussed and the findings are presented.</p> <p align="LEFT"> </p>