No abstract

Coloured pavements have been implemented by metropolitan areas to denote dedicated lanes for bus rapid transit to maintain a high level of safety. Transit benefits of these installations are well documented. However, field performance of various types of coloured pavement has not been investigated systematically, with questions not being answered. In collaboration with the Regional Municipality of York (ON, Canada) where red pavement sections have been in operation for years for its bus rapid transit lanes, the Centre for Pavement and Transportation Technology at the University of Waterloo (Waterloo, ON, Canada) assessed the performance of various types of red pavements including epoxy paint and red asphalt mixes. It was found that, with significant lower texture depth, epoxy paint surface has disadvantages to red asphalt pavement from a pavement texture and safety perspective. The red asphalt sections in this study were observed as lower yet compatible frictional levels to conventional black pavement. Various types of contamination onto the red pavement were observed during field survey. In addition, the ultraviolet radiation degraded the colour of red asphalt pavement over time and may make it less effective for lane designation. Long-term monitoring is recommended to evaluate the functional and structural performance of red asphalt pavement.

No abstract

Asphalt stripping is a common form of distress caused by moisture that creates a loss of bond between the aggregate and binder. It is thought that the use of warm mix asphalt (WMA) technology could lead to increased moisture susceptibility if the free moisture present in the aggregates does not evaporate at the lower mixing temperatures. The purpose of this study is to evaluate the moisture susceptibility of WMA using Evotherm 3G on laboratory prepared and plant prepared mixes. The moisture damage potential was evaluated using the TSR (Tensile Strength Ratio), the static immersion test, MiST. (Moisture Induced Stress Tester) and HWTT (Hamburg Wheel Tacking Tester). Additionally, plant-prepared mixes were also assessed for TSR and rut depth. The results indicated that WMA provided adequate levels of resistance to moisture damage, reduced swelling and improved coating. Laboratory mixes showed reduced resistance to rutting, but rut depth of plant mixes was similar to that of hot mix asphalt.

In North America, highway agencies have started using Superpave as it incorporates a performance-based asphalt binder specification and a mix design analysis system. However, in a pavement management system (PMS), the performance of the pavement structure significantly influences management decisions. In this regard, accurate prediction and evaluation of performance is a very important aspect. With this in mind, this study investigates the performance of Superpave through the mechanistic–empirical (M-E) approach, field-evaluated performance, and laboratory performance tests. It considers 15 sections of highways from Ontario. The investigation found that the international roughness index (IRI) and permanent deformation are overpredicted in the M-E approach compared with field observations. Additionally, to better understand the performance, the dynamic modulus of asphalt mixtures and binder rheological testing are also performed. The master curve developed for the surface mixtures suggests a lower level of fatigue resistance that justifies the bottom-up fatigue failure in the field-observed scenarios.