Flexible Pavement Design in Sherbrooke

Sherbrooke winters are brutal. Frost penetrates deep. The asphalt on your parking lot expands and contracts by centimeters. It cracks. It heaves. Then spring arrives and the ground becomes saturated with meltwater. The subgrade turns to mush. A pavement structure that works in Montreal fails here. The freeze-thaw cycle does not forgive poor design. We specify asphalt concrete thicknesses, granular base gradation, and subbase properties based on local frost depth data. The Saint-François River valley has its own microclimate and soil conditions. Silty tills dominate the area. They are frost-susceptible. We design accordingly. A proper grain size analysis tells us the frost susceptibility of your subgrade. We also run CBR tests to determine the structural number your pavement needs.

Pavement in Sherbrooke fails from the bottom up. The subgrade controls everything. Design the drainage first.

How we work

On Sherbrooke commercial projects we often see base failures caused by poor drainage. The granular layer must be free-draining. It must shed water laterally. We use CSA A23.3 aggregate specifications. The gradation band must be tight. Fines content below 5 percent. Otherwise the base retains water, freezes, and the asphalt layer delaminates by March. Our structural design follows the AASHTO 1993 method adapted to NBCC frost depth requirements. We model traffic loads in ESALs. We account for truck traffic from local industry. The design report includes layer thicknesses, modulus values, and subgrade preparation protocols. We specify tack coats between lifts. We define compaction targets for each layer. The granular base must reach 98 percent modified Proctor density. These are not suggestions. They are survival requirements for pavement in the Eastern Townships.

Local ground factors

Contractors in Sherbrooke sometimes skip the subgrade preparation. They place granular base directly on disturbed native soil. It compacts unevenly. The pavement develops alligator cracking within two winters. Another common error: using recycled concrete as base material without testing. It can contain unhydrated cement that sets up later and creates differential stiffness. Or it retains too much moisture. We have seen entire parking lots need reconstruction after three years because of this. The frost action in silty soils is relentless. If you do not remove frost-susceptible material to at least half the frost depth, you are building on a time bomb. We specify a full-depth replacement or a thick insulating subbase layer. The design must also handle spring load restrictions. Weak subgrade during thaw can rut under construction traffic before the asphalt is even placed.

Technical parameters

Parameter	Typical value
Design method	AASHTO 1993 / Mechanistic-Empirical
Frost depth	1.5 m to 1.8 m (Sherbrooke region)
Traffic loading	ESALs (Equivalent Single Axle Loads)
Asphalt layers	Surface course, binder course, base course
Granular base	CSA A23.3, 0-20 mm or 0-40 mm crushed stone
Subbase	Granular B Type II or engineered fill
Compaction	98% modified Proctor (base), 95% (subbase)
Drainage	Cross-slope 2%, subdrains where required

Related services

Structural pavement design

Layer thickness calculation based on traffic, subgrade strength, and climate. We provide asphalt mix type recommendations and granular base specifications.

Pavement evaluation and rehabilitation

Falling weight deflectometer testing, core sampling, and distress surveys to diagnose failures and design overlays or full-depth reconstruction.

Frequently asked questions

How much does flexible pavement design cost in Sherbrooke?

The cost ranges from CA$2,040 to CA$6,840 depending on the project size, traffic analysis complexity, and whether field testing like CBR or FWD is included.

What is the minimum asphalt thickness for a commercial parking lot in Sherbrooke?

There is no single answer. It depends on subgrade strength and expected truck traffic. Typically, we design 75 to 150 mm of asphalt over 200 to 400 mm of granular base for commercial lots.

Do you account for frost heave in your designs?

Yes. Frost depth in Sherbrooke reaches 1.5 to 1.8 meters. We either replace frost-susceptible soils to that depth or design an insulating subbase layer to prevent freezing of the subgrade.