Concrete

Concrete

Concrete is rigid pavement that is used for sidewalks, curbs, dumpster pads, and sometimes entire parking lots. For optimum performance, concrete should be placed on a solid foundation of crushed stone. The design life of concrete pavements is generally between 25 and 30 years. However, during this time, it will not be maintenance-free. Caulking, spot repairs, removal and replacement of broken sections, and drainage modifications may all be necessary to ensure that the concrete performed as it is intended to. Concrete sidewalk and curb systems almost never get to the point where entire removal and replacement is necessary, unless aesthetics are a major factor.

Contractors in the Pavement Network are experts at identifying the condition of your concrete and recommending solutions (including nothing, if that is an option) based on weather conditions, sub-base conditions, and available materials in any given region. Because of these factors, there is no single solution that will solve concrete problems throughout the different regions of the country. As Pavement Network members, we know that our company’s experts can solve your pavement problems in our own geographical areas and that our network partners can handle your parking lot issues in their geographical areas. You can expect the same high-quality results across the country.

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Dumpster Pads

Concrete is the best material to use for dumpster pads for many reasons. Metal dumpsters and trash trucks exert a large amount of downward force on the pavement.
Since concrete is a rigid material, it will not develop dents and dimples in the surface as asphalt does, leading to premature failure.
If wire mesh or metal rebar is introduced into the slab, it will make an extremely strong concrete and steel matrix that will hold up much longer than asphalt under the heavy load of a trash truck.

Dumpster pads should extend out an additional 10 – 15 feet in front of the dumpster. By doing this, the front wheels of the trash truck can sit on the pad, which will absorb this extremely heavy load. Trash trucks are notoriously leaky due to the heavy strain on their hydraulic system, however concrete is not adversely affected by oil. The hydraulic fluid or other oil that leaks from the trash truck will soften asphalt but will not soften the concrete slab.

The Process

  • Lay out and mark the area where the dumpster pad is to be installed.
  • Set up warning barriers to make the work site safe.
  • Jackhammer or saw cut the perimeter of the existing pad or asphalt to produce a smooth and even edge.
  • Excavate the concrete, asphalt, or other material and haul to recycling facility.
  • Pad should be at least 6″ thick, if subgrade conditions are good. If subgrade conditions are poor, the concrete thickness should be increased to 8″ and additional crushed stone should be installed, if necessary.
  • Install 4″ – 8″ of crushed stone, if warranted, and compact thoroughly using a vibratory tamper.
  • Install 6 x 6 #10 welded wire mesh or 1/2″ (#4) rebar to strengthen the slab. Rebar should be placed on a criss-cross pattern and tied with wire. Wire or rebar should be set on “chairs” so it stays in the middle of the slab. Wire or rebar that falls to the bottom of the concrete does not add additional strength to the matrix.
  • Set concrete forms using metal or wood forms. In some instances, the surrounding concrete or asphalt can be used as the form.
  • Pour pad using 3500 psi or 4000 psi air-entrained concrete. Air entrainment is used for exterior concrete only and helps it endure changing weather conditions.
  • Trowel the concrete level and, if necessary, score control joints in the slab. If the slab is rectangular, then control joints can be used to create “squares” of concrete. The control joints are used to “control” cracking of the slab. As expansion and contraction is a natural occurrence for concrete, it will inevitably crack. It is generally accepted that a square pattern is best to reduce the chance of random cracking in the slab and to allow cracks to form within these joints. The largest square should be no more than 15′ x 15′.
  • Expansion joints may be necessary for extremely large slabs or in areas where the surrounding pavement is also concrete. Your Pavement Network professional can make a recommendation on placement of expansion joints.
  • Apply broom finish to the concrete once it is partially set.
  • Once concrete has completely set, strip forms and remove from the site. Any available dirt from on site can be used to backfill the voids where the forms were, if necessary.
  • Remove any remaining trash or debris.
  • Keep a dumpster pad clear of heavy traffic for a minimum of seven days.

Sidewalks

Concrete is a rigid material that is ideal for sidewalks. It can be transported in its semi-liquid form in wheelbarrows or light transport vehicles from the truck to areas away from paved surfaces where it can be placed by hand and finished without the use of heavy equipment.
This minimizes damage to surrounding areas and landscaping. It does not require continual compaction of vehicle traffic to keep it in sound condition. Concrete sidewalks also remain more level and true than asphalt walkways, which tend to develop dips and random cracks. Generally, concrete cracks occur in the “control joints,” which will not affect the appearance or structure of the sidewalk.

Reinforcing concrete sidewalks with wire mesh helps to bridge over small imperfections in the subgrade. This lessens the likelihood that sinkholes will develop. Concrete sidewalks can be replaced in sections that mesh together nicely, although the color does not always match (few materials do). The design life of concrete is approximately 30 years. This means that over a 30-year period, the entire sidewalk system in a given property will need to be removed and replaced. Usually, it will be done in sections over time.

The Process:

  • Lay out and mark the areas to be removed and replaced. It is recommended that concrete sidewalk be taken out to the nearest joint.
  • Set up warning barriers to make the work site safe.
  • Saw cut the perimeter of the repair area to produce smooth, even edges.
  • 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.
  • Install 6 x 6 #10 welded wire mesh.
  • 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 sidewalk using 3000 psi or 3500 psi air-entrained concrete. Air entrainment is for exterior concrete only and helps the concrete endure changing weather conditions. Concrete should be a minimum of 4″ thick.
  • Trowel the concrete level and score joints in a pattern that keeps the repair area uniform with the surrounding sidewalk. Expansion joints should be placed approximately every 25′.
  • Apply broom finish perpendicular to the direction of traffic.
  • Once concrete has set, strip forms and remove from the site. Any available dirt from on site can be used to fill the voids where the forms were.
  • Remove any remaining trash or debris.

Steps

Concrete is the best material to use for steps because it remains rigid and keeps its form. Over time, however, it can deteriorate, especially when de-icing salts are used. A set of concrete steps is also extremely heavy, and if the subgrade is at all soft, the entire staircase or large portions of it can settle. Removal and replacement of concrete steps can be very tricky because alternate walking routes are not always readily available.

  • Lay out and mark the areas to be removed and replaced.
  • Set up warning barriers to make the work site safe.
  • Construct a temporary staircase, if necessary, using wood.
  • Saw cut the perimeter of the repair area to produce smooth, even edges.
  • Excavate the deteriorated concrete and haul to a recycling facility.
  • If the subgrade is soft or in poor condition, remove to a minimum depth of 4″ and replace with crushed stone. Stone should be leveled and compacted thoroughly using a vibratory tamper.
  • Install 6 x 6 #10 welded wire mesh or 1/2″ steel rebar in a criss-cross pattern. If rebar is installed, it should be tied together to form a single unit.
  • 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. Care should be taken in placement of the concrete forms to produce uniform steps and risers. Inconsistency in steps can easily cause people to trip and fall.
  • Pour steps using 3000 psi or 4000 psi air entrained concrete. Air entrainment is for exterior concrete only and helps the concrete endure changing weather conditions.
  • Trowel the concrete level.
  • Wait for the concrete to partially set and then strip the face forms from the steps, so they can be finished as well.
  • A broom finish should be applied perpendicular to the direction of traffic.
  • The side forms should remain in place (sometimes overnight) until the concrete is hard.
  • Once concrete has set, forms are to be stripped and removed from the site. Any available dirt from on site can be used to backfill the voids where forms were.
  • Remove any remaining trash or debris.

Truck Courts

Concrete is the best material for truck courts for many reasons. When heavy trucks sit on a paved surface for an extended period of time, the wheels can easily sink into an asphalt pavement. Asphalt is a flexible pavement, and in the heat of the summer, it is particularly susceptible to this occurrence. Concrete is a rigid pavement that will not dent. Introducing wire mesh or metal rebar into the slab makes an extremely strong concrete and steel matrix that will hold up much longer than asphalt under the weighty load of heavy trucks.

The landing gear of a tractor trailer exerts an extremely high downward force on the pavement. Landing gear can easily produce dents and deep holes in asphalt pavement and can, in some instances, result in the gear completely falling through the pavement. Concrete is not susceptible to this type of problem. Concrete also is not adversely affected by oil spills. The hydraulic fluids that frequently leak from trucks will not soften the pavement.

The Process:

  • Lay out and mark the area where the truck court is to be installed or repaired.
  • Set up warning barriers to make the work site safe.
  • Jackhammer or saw cut the perimeter of the existing concrete or asphalt to produce a smooth and even edge.
  • Excavate the concrete, asphalt or other material and haul to recycling facility.
  • The new concrete should be at least 6″ thick, if subgrade conditions are good. If subgrade conditions are poor, then the concrete thickness should be increased to 8″ and additional crushed stone should be installed if necessary.
  • Install 4″ – 8″ of crushed stone, if warranted, and compact thoroughly using a vibratory tamper.
  • Install 6 x 6 #10 welded wire mesh or 1/2″ (#4) steel rebar to strengthen the slab. Rebar should be placed in a criss-cross pattern and tied with wire. Wire or rebar should be set on “chairs” so it stays in the middle of the slab. Wire or rebar that falls to the bottom of the concrete does not add additional strength to the matrix.
  • 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 3500 psi or 4000 psi air-entrained mix. Air entrainment is used for exterior concrete only and helps it endure changing weather conditions.
  • Trowel the concrete level and score control joints in the slab. If the slab is rectangular, then control joints can be used to create “squares” of concrete. The control joints are used to “control” cracking of the slab. As expansion and contraction is a natural occurrence for concrete, it will inevitably crack. It is generally accepted that a square pattern is best to reduce the chance of random cracking in the slab and to allow cracks to form within these joints. The largest square should be no more than 15′ x 15′.
  • In large slabs, expansion joints should be installed at regular intervals. Your Pavement Network professional can make a recommendation on placement of expansion joints.
  • Apply broom finish to the concrete once it is partially set.
  • Once concrete has completely set, strip forms and remove from the site. Any available dirt from on site can be used to backfill the voids where the forms were, if necessary.
  • Remove any remaining trash or debris.
  • Keep the truck court free of heavy traffic for a minimum of seven days.

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. The 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.

The Process:

  •     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.
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