FULL SERVICE OIL SPREADING
All distributor trucks in Diversified’s fleet use the Bearcat CRC (computer rate control) system. The CRC system controls the asphalt pump and monitors truck speed, distance traveled, flow rate and spray bar width. Exact and consistent spread rates within .01 gallon (± 1%) per square yard, are achieved with no operator calculations or adjustments.
A tack coat is a very light application of asphaltic emulsion or paving asphalt on an existing pavement surface. A tack coat is used to ensure a good bond between the existing pavement surface and the new asphalt concrete overlay and between the layers of each lift of asphalt concrete as well as vertical surfaces that the new pavement will be placed against.
Asphaltic emulsion consists of three basic ingredients: paving asphalt, water, and emulsifying agent. The most commonly used emulsion is SS1H. Paving asphalt is the byproduct of refining crude petroleum. Any grade of paving asphalt is acceptable as a tack coat material, however the most commonly used is PG64-10. Local experience and engineering judgment may dictate which type of material is ultimately used. For consideration, the following information and experience is offered for each material type. Emulsions are most commonly used. However, they take longer to break then paving asphalts. For this reason, they are not recommended for use as a tack coat in relatively cool weather, at night, or when there is a short construction window. Paving asphalt is used for night work or work in cool weather because paving asphalt does not require any time to break before it can be overlaid. Paving asphalt is commonly used as a tack coat material for rubberized asphalt concrete (RAC) overlays.
Fog seals are a method of adding asphalt to an existing pavement surface to improve sealing or waterproofing, prevent further stone loss by holding aggregate in place, or simply improve the surface appearance. (See above before (L) and after (R). To achieve this, the fog seal material (emulsion) must fill the voids in the surface of the pavement. This is accomplished in two steps. First, prior to application the surface must be thoroughly cleaned, using any combination of a blower, sweeper truck, and/or water truck. Second, during its application it must have sufficiently low viscosity so as to not break before it penetrates the surface voids of the pavement. This is accomplished by using a slow setting emulsion that is diluted with water.
Fog seals should only be used where surface penetration of the emulsion can be expected; that is, aged and raveled hot mix surfaces, chip-sealed surfaces, and open graded asphalt surfaces. On shoulders, gores, or dikes, penetration is desirable, but it is not essential. Fog seals darken the pavement surface and create distinct demarcation in these regions.
PAVING FABRIC INSTALLATION
Cracked pavements allow surface water to permeate subgrade soils, which saturate and weaken the subgrade. Normal maintenance procedure is to repave with an asphalt overlay. This resurfacing procedure can extend the useful life of a pavement section at a lower cost than a full replacement. However, the extended useful service life of an overlay can be reduced by subgrade saturation/weakening which causes fatigue cracking and propagation of cracks from the original pavement through the existing overlay (reflective cracking). The addition of paving fabric into a pavement overlay reduces the effect of mechanisms which deteriorate pavements and increases the life of the overlay pavement section. When installed with a proper surface preparation and tack coat, paving fabric forms an impermeable membrane that prevents the penetration of surface water through the pavement and also provides a stress relieving layer which inhibits reflective crack growth.
The two most common paving fabrics used in today’s market are Mirafi®’s MPV-(series) and Owens Corning Trumbull’s Trupave®. Diversified Asphalt Products, Inc. uses specially modified John Deere tractors enabling us to install paving fabrics in a wide range of projects, from the tiniest parking lot to a major street renovation.