Overview of Specifications for Unbound Granular Base Materials in Selected Canadian Provinces and Neighbouring States

摘要

Specifications for unbound granular base materials vary among transportation agencies based on the availability of materials, climatic conditions, and function. Specifications aim to provide durable materials that meet design requirements and achieve the target design life. This paper compares Manitoba Infrastructure and Transportation (MIT) specifications for unbound granular base materials with the specifications developed by selected Canadian provinces and neighbouring States. This work is part of a research project to evaluate the effect of base material gradation on performance and, if required, update current MIT specifications for unbound granular base materials. The comparison showed that MIT specifications allow a higher percentage of fines (particles passing sieve No. 200). MIT's maximum particle size (19 mm) is generally smaller than the maximum particle size in other specifications (25 to 37.5 mm). The effect of the base material gradation and fines content on the stiffness and stability is being evaluated in the laboratory. Results of laboratory tests will be used to update current specifications, if required, and develop performance-based parameters for pavement design using the Mechanistic-Empirical Pavement Design Guide (MEPDG).