Understanding Hot Mix Asphalt (HMA)
Hot Mix Asphalt is the gold standard for all commercial and residential paving. It is produced at regional asphalt plants by heating aggregate sand and crushed stone to over 300°F before coating it with hot petroleum asphalt cement (bitumen).
Because HMA hardens rapidly as it cools below 185°F, it must be delivered in insulated truck beds, laid out immediately by an asphalt paver screed, and compacted thoroughly with multi-ton vibratory steel rollers while hot. Once cured, HMA forms a virtually impermeable, flexible monolithic slab.
Understanding Cold Patch Asphalt
Cold Patch asphalt consists of aggregate stones coated with asphalt cement blended with solvent cutting agents or proprietary polymer additives. These chemical solvents keep the asphalt pliable and workable at freezing winter temperatures straight out of a 50 lb plastic bag.
When packed into a pothole and compressed under vehicle tire weight, the solvents slowly evaporate, allowing the mix to firm up. While fantastic for emergency winter repairs when hot mix plants are shut down for the season, cold patch does not possess the structural cohesion of hot mix and should never be used to pave an entire driveway.