Abstract Manager

Many haul road corridors serve as economic lifelines for northern resource development.   However, due to the remote nature, northern haul roads are often built out of relatively poor locally available materials and are often unsurfaced roads as paving is often too cost prohibitive and/or not warranted given the low AADT count.   Northern roads can also be highly susceptible to differential heave and settlements due to the combined effects of heavy traffic loadings, poor in situ silty soils, poor select materials availability for sealing, frost heave, spot road repair activities, severe rain events, wash-boarding, etc.  Many of these roads require engineering materials and systems that specifically provide uniform load carrying capacity and improved climatic durability within the road structure.

The objective of this study was to examine the use of composite expansive polyurethane foam systems with asphalt emulsions specifically designed to provide improved particle coat ability to ensure complete continuity of the mastic surrounding the granular particles with minimal volume of materials added.  The expansive systems considered herein were engineered for improved structural shear behavior and climatic durability within unsurfaced road structures.  These systems were designed to provide high elastic strain capacity for load dissipation and to mitigate moisture infiltration to reduce differential strains due to interstitial moisture within the composite structure when under dynamic loadings of trucks.    

Triaxial frequency sweep material constitutive relations were obtained from samples generated from a balanced chemical and mix design process across various typical northern Canadian sands and gravels.  Mechanistic road modelling using PSIUnsurfaced3D was performed to determine the mechanical behavior across 3D strains experienced in realistic northern field state and heavy resource haul conditions. 

This paper demonstrates the use of engineered blends of expansive polyurethane foam systems with select asphalt emulsion systems engineered for system compatibility as well as uniform coat ability.  When tailored for specific sand and gravel grain size distributions of in-situ northern road materials, these engineered additive systems can significantly improve the structural primary response of in-situ northern roads materials for reasonable materials supply and constructability using modern full depth reclamation equipment.