CHIP SEAL EQUIPMENT
Asphalt Distributor - the function of the asphalt distributor is to apply the binder uniformly and in specified quantities. The distributor consists of a truck- or trailer-mounted insulated tank ranging in capacity from 800 to 5,500 gallons (3,000-20,800 liters).
Most distributors are equipped with a heating system that will maintain the binder at the proper spraying temperature and has a system of spray bars with nozzles that apply the binder to the roadway surface. These spray bars cover widths up to 30 feet (10 meters) in one pass.
The asphalt distributor is the most complex piece of equipment used in chip seal construction work because it has many components, and all must be operating properly.
The major components are:
Periodic calibration of the distributor should be performed to ensure that the proper rate of binder is being applied.
Aggregate Spreader - the function of the aggregate spreader is to apply a uniform aggregate cover at a specified rate over the freshly sprayed binder. Aggregate spreaders should be self propelled and have a continuous feed feature. The major components of the aggregate spreader are:
Calibration is key for the chip spreader. This should be checked regularly to ensure the correct application rate is being applied.
Rollers - the functions of the roller are to:
A pneumatic roller is recommended for all chip seal work and operates on rubber, air-inflated tires. A pneumatic roller must be self-propelled and capable of operating in both forward and reverse.
A roller may be used for the slurry seal/micro surfacing application if placed in a low traffic environment such as a parking lot or cul-de-sac.
Pneumatic tired rollers should be a 12 ton minimum with a contact pressure of 60 psi.
Sweeping Equipment - the functions of the sweeping equipment are to:
There are three different types of sweeping equipment typically used in chip seal construction:
Bristles on the rotary broom should be nylon or plastic and checked for evenness.
Front End Loader - the function of the front end loader is to move aggregate from the stockpile into the haul truck.
The front end loader should be leak free and in good condition.
Haul Truck - the function of the haul truck is to transport the aggregate and dump it into the aggregate spreader. They are normally either tandem-axle or single axle trucks. Haul truck components to check:
Make sure haul trucks are clean and that no debris is remaining in bed.
SLURRY SEAL AND MICRO SURFACING EQUIPMENT
Slurry seal/micro surfacing is placed by a paver specifically designed and manufactured to apply micro surfacing. The paver is a continuous-flow metering and mixing unit that accurately delivers and proportions the mix components through a multi-blade, double-shafted mixer. To minimize construction joints, the paver is capable of loading materials while continuing to apply slurry seal/micro surfacing. The operator has full control of the forward and reverse speeds during application, while the driver can operate from either side to maintain alignment.
Slurry seal/micro surfacing can also be placed with truck mounted micro surfacing pavers. These pavers feature the same continuous-flow, accurate delivery and proportioning of the mix components through a multi-blade, double shafted mixer. However, a truck mounted paver is loaded with materials at the stockpile, drives to the project site, applies slurry seal/micro surfacing until empty, then returns to the stockpile for refilling. There will be more construction joints while using a truck mounted paver, however it is a popular option.
NURSE TRUCKS/MOBILE SUPPORT UNITS:
Nurse trucks bring aggregate, asphalt emulsion and water to the continuous paver. The bodies are specifically designed to properly deliver these three materials to the paver and allow quick changeovers while maintaining the paving process. A typical project will require three to five nurse trucks, depending on the speed of construction, and the distance from the stockpile to the jobsite.
The mixture is spread uniformly by a spreader box utilizing augers to move the material. The rear of the spreader box features an adjustable primary strike-off to determine the application rate, and a secondary strike-off to apply the proper finish texture.
Note: A standard spreader box is used to apply leveling (scratch) courses and finish courses, the primary strikeoff must be changed from a flexible material to a rigid material when applying the leveling course.
Note: A rut filling spreader box is used to fill ruts 1/2 inch (1.3 cm) or greater in depth.
For slurry seal, the spreader box may also have a drag on the back to texture the material. Burlap is commonly used. While it is common to use a spreader box specifically designed for slurry seal, slurry seal can also be placed by spreader boxes designed for micro surfacing.