The City of Calgary (The City) initiated one of the first Warm Mix Asphalt (WMA) technology
projects in Canada in 2005 with Tetra Tech Canada Inc. A follow-up assessment of that project
was completed in 2021. This paper discusses the evaluation of the 2005 project data and the
outcomes of the follow-up investigation.
The Demonstration Project to evaluate WMA was constructed in Calgary in 2005. The project
compared three surfacing mix types: a control mix and two WMA alternatives. The project
successfully implemented the new technology.
The 2021 assessment had the objective of reviewing details from the original project, completing
a field assessment of the current conditions, and implementing a suitable laboratory program to
assist The City in determining the feasibility of future use of WMA technology.
The 2021 assessment studied the relative strength of the WMA layers and binder properties to
determine the difference between Hot Mix Asphalt (HMA) and WMA. An industry assumption is
that WMA is prone to reduced stiffness given the reduced mixing temperatures; however, the
outcome of this trial project opposed this assumption and the results indicate that these WMA
technologies could be considered equivalent to HMA in terms of design and performance.
