Where the strength, durability and environmental benefits of concrete are desired but fast placement is critical, whitetopping is an excellent choice for asphalt pavement repair. Prairie has the materials and support needed to help you achieve smooth results with this technique.

Whitetopping can be used to replace worn-out asphalt found in airport pavements, parking lots, urban roadways and alleys, bus pads, residential roads and other paved surfaces open to low-speed traffic. With a curing time of less than 24 hours, many ultra-thin whitetopping projects can reopen to traffic within 1-2 days.

Benefits

• Superior strength and durability. The whitetopping mix reaches strengths of 3,000 psi or more, and lasts 2 to 3 times longer than asphalt paving.
• Lower costs. At current prices, concrete often costs less than asphalt from the first dollar. And properly designed concrete overlays will deliver 20 to 40 years of service, greatly reducing maintenance costs over time.
• Safety. Whitetopping creates an attractive, bright-white roadway that reflects 3 times more light than asphalt, helping increase motorists’ safety as it reduces lighting costs. The rutting, shoving and rippling that create driving hazards on asphalt surfaces are all but eliminated.
• Environmental benefits. Unlike asphalt, concrete contains no VOCs and therefore does not emit toxins into the atmosphere. The cooler surface temperatures of concrete also reduce the heat-island effect in urban areas. And the use of existing asphalt as a base reduces waste that would end up in landfills.

Thin vs. ultra-thin whitetopping

Thin whitetopping is applied at a depth of 4-6 inches over asphalt that has been leveled and repaired and is used where greater strength is required, such heavy truck traffic. Ultra-thin whitetopping involves placement of 2-4 inches of concrete over a milled asphalt surface, bonding with the underlying asphalt to create a strong composite pavement. Ultra-thin whitetopping is designed to renew the surface of worn asphalt pavements and not to increase structural capacity. The mix used for ultra-thin applications is reinforced with fibers and other additives to achieve rapid strength gain and ease of placement.

Construction considerations

Proper preparation, placement and early entry saw cutting are the keys to the success of ultra-thin whitetopping projects. Many installers mill off the amount of asphalt that will be replaced by the UTW so that they don’t change the surface grade. Milling can act as formwork which will reduce the preparation time and the need to strip forms. Any serious failures in the underlying asphalt base will need to be repaired prior to the pour. Potholes and ruts deeper than 2” should be repaired. The base itself should be 2 – 3” deep. Laser screeds are ideal for whitetopping projects allowing precise placement for crowns, swales, pitches and flow lines and the ability to change thickness from 2″ to 3″ to 6″ all in one pass. 

Joint spacing is critical to good performance. Successful projects use a short joint spacing to form, in effect, a mini-block paver system. Joints are sawed early to control surface cracking.