Section 2: Rotary BroomAnchor: #i1007474
The pavement must be adequately broomed before asphalt is applied. This must be performed thoroughly to ensure an adequate bond of the asphalt to the pavement. A finished seal coat will also be broomed to remove excess aggregate particles. Power rotary brooms are used for these purposes. An example of a rotary broom is shown in Figure 7‑1. A vacuum sweeper is another type of broom which may also be used to clean the pavement.
Figure 7-1. Rotary Broom.
Rotary brooms for seal coat work should be self-propelled, four-wheeled, and capable of operating in both forward and reverse. They are powered by either a gasoline or diesel engine. The bristle brush should be capable of being raised, lowered, and rotated horizontally. The bristle brush on a rotary broom is shown in Figure 7‑2.
Figure 7-2. Bristle Brush on Rotary Broom.Anchor: #i1007509
As with other pieces of equipment, the manufacturer’s name, model number, and serial number may be recorded and entered in the project folder. The inspector should record in the project diary that the equipment was inspected and found acceptable for use on the project.Anchor: #i1007519
The rotary broom, or sweeper as it is often called, operates well ahead of the rest of the equipment. This puts it in a very vulnerable position on many roads, due to its tendency to create dust and the exposure to traffic. Safety markings, lights, and flags must be in place on the broom and checked for the benefit of the traveling public as well as the sweeper operator.Anchor: #i1007529
The bristles may be nylon or fiber, or some may be a combination of nylon and steel bristles. The bristles on the sweeper should be checked to ensure they are in good condition. The width of the brush should be checked for evenness. If the bristles are worn off unevenly, too much pressure will be exerted in one spot and the bristles may not make contact in another. If there is a visible unevenness, the bristle assembly should be replaced.Anchor: #i1007539
The brush should be inspected to see that it can be raised and lowered and that it can be rotated horizontally. It should be capable of discharging aggregate to the left or right. The brush controls should start and stop the rotating promptly.Anchor: #i1007549
Older Model Brooms
Some of the older types of brooms have a separate hydraulic cylinder at each end of the broom, which raise and lower the brush assembly. These cylinders are operated with separate controls. Sometimes, the two cylinders do not exert even pressure, causing one end of the broom to exert heavy pressure on the pavement while the other end barely contacts the surface. This is not a problem with newer models, since they are now manufactured with single controls. If an older model is being used on the job, care should be taken to watch for uneven pressure at opposite ends of the brush.