Curb & Gutter
Concrete curb and gutter is generally installed at the perimeter of a road or parking lot. Not only does it define the edges of the lot, but it actually holds the pavement in place and serves as a “termination” to keep the pavement from expanding and deteriorating.
For example – an asphalt driveway does not have a termination edge, and you will usually notice that it breaks up along the edges first. The edge is the weakest point and as vehicles roll over it, it can push outward into the dirt area causing it to fail.
The part of the curb and gutter that you don´t see is approximately 8 inches thick, below grade, forming an extremely strong barrier.
The drainage patterns in most parking lots are engineered using the “gutter pans” of the curb and gutter as flow lines. Concrete can be placed much more precisely than asphalt can, giving even fairly flat lots the ability to drain. Curb and gutter is the first part of the parking lot to be installed and is done to a strict tolerance. The asphalt is usually placed so that it drains toward the curb and gutter, thus allowing the water to eventually flow to the catch basin or other exit point.
- Lay out and mark the areas to be removed and replaced. It is recommended that concrete curb and gutter be taken out to the nearest joint.
- Set up warning barriers to make the work site safe.
- Saw cut the edge of the repair and produce a smooth edge.
- Excavate the deteriorated concrete and haul to a recycling facility.
- If the subgrade material is soft or in poor condition, remove it to a minimum depth of 4″ and replace with crushed stone. Stone should be leveled and compacted thoroughly using a vibratory tamper.
- Set concrete forms using metal or wood forms pinned at sufficient intervals to keep the forms from disfiguring or “blowing out” when the concrete is introduced.
- Pour concrete using 3000 psi or 3500 psi air-entrained concrete. Air entrainment is used for exterior concrete only and helps the concrete endure changing weather conditions.
- Trowel the concrete level and score joints at 10′ intervals. Expansion joints should be placed approximately every 100′.
- Pull the face forms of the newly placed concrete once it has partially set, and trowel the curb face.
- Apply the broom finish parallel to the direction of the curb.
- Once concrete has set, strip forms and remove. Any available dirt from on site can be used to backfill the voids where forms were.
- Remove any remaining trash or debris.