The Pavements Laboratory

The pavement laboratory consists of binder characterization equipment for the PG grading of binders and mix preparation and testing equipment. In addition, the laboratory has a number of general bench top tools and data recording instruments.

The Rotational Viscometer (RV) evaluates the viscosity of the binder at temperatures similar to those commonly used during production to ensure the binder will .

The Dynamic Shear Rheometer (DSR) is used to evaluate the original and short term aged binder properties at the warmest expected pavement temperature. By changing the diameter of the specimen the same test method and equipment can be used to determine binder properties after long term aging and at intermediate in-service temperatures.

 

Short term binder aging is accomplished by the Rolling Thin Film Oven (RTFO). The RTFO simulates aging from hot mixing and construction. Glass jars with 35 g of asphalt fit snuggly in the circular openings of the rotating carriage. A hot jet of air is applied to the samples for 85 min while the bottle tray is rotated to expose binder surfaces to heat.

 

A Pressure Aging Vessel (PAV) treatment of the RTFO binder is used to further age the binder. This simulates long term aging in-service from 7 to 10 years.

 

The Bending Beam Rheometer (BBR) is used to measure the stiffness of asphalt cement. A simply supported beam is held at a constant temperature in a water bath. Deflection at the centre of the beam is measured under an applied constant load at the same location. The stiffness can then be calculated based on the deflection and geometry of the specimen.

 

The Gyratory Compactor is used to determine the bulk specific gravity of an asphalt pavement sample. The equipment applies a standard pressure on the loose mix while gyrating the mold from side to side. The gyratory compactor assists in selecting aggregate blends for asphalt mixes that do not compact too easily and do not continue to compact under traffic loading. The compactor is required for the Superpave mix design method.

 

The Ground Penetrating Radar (GPR) is used to locate anomalies in the pavement structure such as voids, reinforcing steel, dowels, and layer thicknesses. Some photos from a field survey are located here.