From the ground up

Why a strong gravel base is important?

A driveway is only as strong and durable as its foundation. A good base provides a stable and solid foundation for the asphalt surface. Here are the reasons why a good base gravel is important:

1.    Load Distribution: The base gravel distributes the weight of vehicles evenly across the underlying soil. It helps prevent the asphalt from cracking or rutting under heavy loads. A properly designed and compacted base gravel layer ensures that the load is spread out and transferred to the underlying soil without excessive deformation.

2.    Moisture Control: Base gravel acts as a drainage layer, allowing water to drain away from the road surface. If water is allowed to accumulate beneath the asphalt, it can weaken the base and subbase layers, leading to pavement failure. Good base gravel helps to maintain the structural integrity of the road by controlling moisture and preventing water-related damage.

3.    Stability and Uniformity: A well-compacted and uniform base gravel layer provides stability to the entire pavement structure. It minimizes differential settlement and ensures that the surface remains level and smooth. Uneven or unstable base gravel can cause the asphalt layer to crack, deform, or develop potholes.

4.    Frost Protection: Here in Southern Alberta, frequent freeze-thaw cycles are a fact of life. Properly designed and installed base gravel helps to prevent frost heave, which occurs when moisture in the ground freezes and expands, causing the pavement to lift and crack. The base gravel layer acts as a buffer and reduces the impact of freeze-thaw cycles on the asphalt surface.

5.    Longevity: An asphalt road is only as good as its base. By providing a strong and stable foundation, a good base gravel layer increases the lifespan of the pavement. It helps to distribute stresses, resist deformation, and prevent premature failure, ensuring that the road remains in good condition for a longer period.

Placing Gravel

Subgrade preparation is critical for durable gravel. The clay must be graded and compacted to the required slope and density. After subgrade is complete, geotextile (if required) will be placed on some or all the surface. Gravel will then be spread and graded with a motor grader or other equipment to the correct elevation. Water is often applied to aid compaction as the gravel is compacted with steel rollers.

Geotextiles

Geotextiles are widely used in road construction for various applications due to their beneficial properties. These synthetic fabrics are designed to perform specific functions when incorporated into the road layers or subgrade. Here are some common uses of geotextiles in road construction:

1.    Separation: Geotextiles are used to prevent the mixing of different soil layers. They act as a barrier between the subgrade (existing soil) and the aggregate base course (road base) by preventing the migration of fine particles from the subgrade into the base course. This separation function helps maintain the integrity and stability of the road structure.

2.    Filtration and Drainage: Geotextiles can be used to facilitate proper drainage within the road structure. They allow water to pass through while preventing the migration of soil particles. Geotextiles can be placed on the sides of the road to act as filters, allowing water to drain away while retaining the soil particles and preventing the clogging of underlying drainage systems.

3.    Erosion Control: In areas prone to erosion, geotextiles are employed to stabilize slopes and embankments. They are used as erosion control blankets or mats to protect the soil surface from erosion caused by rainfall, runoff, or wind. These geotextiles help in establishing vegetation by providing a stable growth medium.

4.    Reinforcement: Geotextiles can be utilized to enhance the strength and stability of the road structure. They are placed between different layers, such as subgrade and aggregate base, to increase the load-bearing capacity. Geotextiles used for reinforcement purposes are typically stronger and have high tensile strength to distribute loads and minimize deformation.

Pavement Overlay: Geotextiles can be employed in pavement overlays to retard reflective cracking. Reflective cracking occurs when cracks in the underlying pavement propagate through the overlay. By placing a geotextile interlayer between the existing pavement and the overlay, the geotextile acts as a stress-absorbing membrane, reducing crack propagation and extending the life of the overlay.

A Good Foundation

For these reasons and more, it is crucial that your driveway has a solid base layer before placing asphalt. There is no better time to repair or replace the gravel base than when repairs or replacement of the asphalt is planned. PavePros can help construct new, repair or replace your gravel base to ensure your pavement surface is prepared for success!