Types of concrete pavement shoulder

The shoulder to the concrete pavement could be unpaved or paved; again, the paved shoulders could be concrete or bituminous - they are discussed in the following.

Unpaved shoulder

If shoulder is unpaved, it should be well-shaped and attention should be paid to keep it in shape during maintenance operation. This is necessary for proper and quick drainage of the surface run-off. The slope is kept steeper than the main carriageway.

Paved shoulder

Paved shoulder prevents water percolation into the subgrade of the pavement more effectively than unpaved shoulder.

Concrete shoulder

The existing concrete slab can be widened (with same or lowered thickness) beyond the carriage-way width to form a paved shoulder, known as integral concrete shoulder (Austroards 2004). This is a preferred design than disjointed concrete shoulder, because this substantially reduces the stress and deflection of the carriage-way slab (Swanlund and Vanikar 2002, Benekohal et al. 1990) and shoulder drop-off failure is almost eliminated (FHWA 1990). Field investigations show that pavement with widened slab concrete shoulder exhibit little faulting and transverse cracking (Swanlund and Vanikar 2002).

Bituminous shoulder

The bituminous shoulder is less expensive than concrete shoulder and provides desirable contrast between the carriageway and the shoulder. However, the joint (longitudinal) between the concrete carriageway and the shoulder is difficult to maintain. Infiltration of moisture through the joint causes fast deterioration of the asphalt shoulder (Swanlund and Vanikar 2002).