Asphalt Concrete Properties testing and Performance assessment: 26 years of service on elevated road

Abstract

Don Muang Tollway is 6 lanes elevated road. There are 3 lanes in each carriage way. The length is 21 km approximately. There are 24 on-off ramps. Superstructure is 25.35 m width. The structure is comprised of 10 T-girders with 18 cm concrete deck slab overlaid by 5 cm thick asphaltic pavement. Strip seal expansion joint was installed at the end of each span into concrete deck. Asphaltic plug joint was overlaid over the joint. AADT is approximately 100,000 trips/day. Tollway has been in service since 1994. In order to ensure 26 years old pavement quality, asphaltic concrete material has been tested. Samples of each lane were collected every kilometer. Marshall method such as density, void ratio, asphalt content, stability & flow has been performed. Pavement properties have been measured. International Friction Index (IFI) were measured by fixed slip method. International Roughness Index (IRI) and rut depth were measured by laser profilometer. All of the test results were overlaid together using GPS basis couple with pavement photographs. Pavement properties were diagnosed and evaluated. Total 197 cored samples were tested. Density is 2.22-2.46 g/sq.cm. Void ratio is 1.7-11.3%. Asphalt content is 4.95-5.13%. Stability is 2,560-6,850 lb. Sample of 99% has properties fall within Department of Highway’s standard# 408. Average rut depth is 5.11 mm, 99.5% is within standard. Average IRI is 2.71 m/km, 94.9% is within standard. Average IFI value is 0.41, 95.6% is within standard. These properties are beyond expectation for 26 years old pavement. Smoothness and friction are still good in service.