Stone mastic asphalt (SMA) trials in Ontario have proven most favourable. SMA, a dense gap-graded mix with high rugosity, has demonstrated enhanced durability, friction, stability and fatigue properties compared to conventional surface course mixes. Based on this positive experience, Metro Toronto Transportation selected SMA for resurfacing a section of Lake Shore Boulevard during the fall of 1995. This major arterial road resurfacing project forms part of the Molson Indy high-speed car race track, which provides `accelerated' SMA testing conditions with high shear stresses. The SMA incorporated trap rock aggregates, limestone filler, cellulose fibre and polymer modified asphalt cement. There were no significant problems encountered with the SMA mix design, production, placement or compaction. Life-cycle cost analysis of the SMA shows it to be economically favourable compared to conventional surface course mixes. Characterization testing in the Nottingham Asphalt Tester shows SMA to have enhanced rutting resistance and fatigue endurance. Pavement performance monitoring before and after the 1996 summer Molson Indy race showed no SMA deterioration due to this severe usage, with the surface remaining in excellent condition. There do not appear to be any technical, logistical or life-cycle cost impediments to wider use of SMA in the urban context. (A)
Samenvatting