Hot Mix Asphalt

Hot mix asphalt (HMA) consists of a combination of aggregate uniformly mixed and coated with asphalt cement. To dry the aggregates and to obtain sufficient fluidity of asphalt cement for proper mixing and workability, both the aggregate and asphalt must be heated prior to mixing—hence the term “hot mix.”

Aggregates and asphalt are combined in a mixing facility in which all of the constituent materials are heated, proportioned and mixed to produce the desired paving mixture. After 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, even surface. While the paving mixture is still hot, the material is further compacted by heavy motor-driven rollers to produce a smooth, well-consolidated pavement layer.

Hot mix asphalt paving mixtures may be produced from a wide range of aggregate combinations, each having its own particular characteristics suited to specific design and construction uses. In addition to the amount and grade of asphalt used, the principal characterises of the mix are determined by the relative amounts of course aggregate, fine aggregate and mineral filler.

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Design Fundamentals 101

Hot mix asphalt (HMA) consists of two basic ingredients: aggregate and asphalt binder. HMA design is the process of determining what aggregate to use, what asphalt binder to use and what the optimum combination of these two ingredients ought to be.


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Asphalt Cements

Asphalt cement is a strong, versatile and weather- and chemical-resistant binding material that adapts itself to a variety of uses, perhaps most commonly to bind crushed stone and aggregate into a firm, tough surface for roads, streets and airport runways.


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Bond/Tack Coats and Primers

A bond coat is a spray application of asphalt emulsion. It is applied to an existing asphalt or portland cement concrete surface prior to a new asphalt overlay or patching.


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Asphalt Additives and Modifiers

McAsphalt provides the road construction industry with the highest-quality asphalt additives, which increase adhesion between asphalt cements and aggregates and improve pavement performance via reduced pavement rutting and moisture-induced damage.


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Pavement Maintenance

Pavement preservation is a strategy that uses “the right treatment, to the right road, at the right time.” Pavement preservation makes scarce dollars go further—every dollar spent will minimize expensive rehabilitation and reconstruction costs in the future.


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