Subgrade Soil Frost Susceptibility Assessment for Pavement Design in Manitoba

Frost susceptible subgrade soils, when exposed to moisture and freezing condition, cause frost heaving on road surfaces. In cold climates, like Manitoba, many road sections experience surface roughness and pavement deterioration due to seasonal frost heaving and melting. Subgrade soils frost heave remedial measures such as removal and replacement, embankment construction using non‐frost susceptible materials, soil stabilization or thick pavement structures are generally very costly and/or impractical. Moreover, available guidelines or study results for characterizing soils as frost susceptible and classifying into different severity levels vary widely. Remedial measures or management of frost heave issues also vary among highway agencies. All these variations or factors hinder the selection of an appropriate approach to deal with this issue.

In Manitoba, in the past, a subgrade soil was characterized as frost susceptible if it met several
characteristics. If a soil was characterized as frost susceptible, the calculated structural number (SN) was increased by 25%. The historical basis for such characterization and a fixed adjustment is unknown. Manitoba has now adopted the “value for money analysis approach” for all design, construction and operational practices. This led to a review of the appropriateness of these method/practice and revise to meet Manitoba’s current needs. Manitoba has completed major changes to frost susceptibility characterization/classification and pavement structure design/analysis for frost susceptible subgrade soils. This led to a more cost‐effective and reasonable pavement structure design and management. This paper presents the comparison of various frost susceptibility characterization and classification, Manitoba’s past practice and recent changes, and the impacts of these changes. This paper and presentation may be an educational opportunity for interested individuals or agencies.


Ahammed, M.A.

Session title

Testing and Modelling of Road and Embankment Materials


Soils and Materials Standing Committee