PROPERTY OWNERS' ASSOCIATION
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"ROAD WORDS”… "and other mysteries of life"
You will be hearing more and more of the terminology used below. This glossary is intended to provide you with some insight to differentiate the various terms and to encourage you to ask questions about the road situation.
HMAC: Hot-mixed Asphaltic Concrete ("HMAC") consists of a combination of aggregates uniformly mixed and coated with asphalt cement. To dry the aggregates and obtain sufficient fluidity of the asphalt cement for proper mixing and workability, both must be heated prior to mixing - giving origin to the term "hot-mix". The aggregates and asphalt are combined in an asphalt mixing plant in which they are heated, proportioned and mixed to produce the desired paving mixture. After the plant mixing is complete, the hot-mix is transported to the paving site and spread with a paving machine in a loosely compacted layer to a uniform, smooth surface. While the paving mixture is still hot, it is further compacted by heavy self-propelled rollers to produce a smooth, well consolidated course.
Paving machine spreading HMACCurb: A curb is often used along the edge of a road. When a curb is used the designer may or may not include a shoulder in the design. Normally the curb will be either shaped to control drainage or flat to constrain the edges of an HMAC pavement and act as a grass barrier. If the curbing is flat, it is usually 12 or 18 inches wide, constructed of Portland Cement Concrete, and generically referred to as "ribbon curbing". However, curbing may also be constructed of HMAC materials. Ribbon curbing adds approximately 45% to the cost of a road. Since curbs add to the cost of a road, they are rarely found in rural areas except where certain drainage conditions (such as mountains or culverts) make them necessary.
HMAC with ribbon curb on Thanksgiving Mountain RoadShoulder: The road shoulder is that portion of the roadway that lies outside the load-bearing surface. For most designs, the shoulder will bear only emergency loads. The chief value of the shoulder is to protect the road base material from moisture and to exclude growth of grasses, etc., from the riding surface of the road.
Road Base: The road base is the prepared structure that under lies the riding surface of the road. It provides the stable foundation that is required to maintain support for the riding surface.
Base Failure: Base failure results from deterioration of the road base from water infiltration or damage from any condition which results in the road base being incapable of supporting the load transmitted from the riding surface.
Seal coating is a process used to maintain the driving surface of our roads to minimize wear and prevent water infiltration into the base material under the road surface. It is accomplished by spraying a uniform, but very thin, layer of liquid asphalt on the road surface, covering it with a layer of graded rock (Horseshoe Bay uses 1/5” diameter rock) and compacting the rock with a mechanical roller.
Asphalt distributor left, followed by a rock spreader, and roller.
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