Hot mix asphalt is for structural paving (new driveways, roads). Cold mix asphalt is strictly for small repairs and filling potholes. You cannot pave an entire driveway with cold mix.
I get calls every spring from homeowners wanting to know if they can just buy a pallet of cold patch bags at Home Depot and pave a new driveway extension themselves. The answer is always a hard no. Here is why.
Hot Mix Asphalt is the backbone of the world's infrastructure. It is heated to over 300°F at the plant. While it is blazing hot, the liquid asphalt cement acts like a lubricant, allowing the crushed rocks and sand to be compacted tightly together by heavy rollers.
As it cools, it hardens into a solid, structural surface that can support multi-ton vehicles. Because it relies on heat to remain workable, it must be laid within a few hours of leaving the plant.
Use Hot Mix For:
Cold mix asphalt (often sold in 50lb bags) is essentially gravel mixed with an asphalt binder that has been cut with a solvent or emulsion to keep it soft at room temperature. It does not require heating. You dump it out of the bag and tamp it down.
However, it never cures to the rock-hard structural integrity of hot mix. It stays slightly pliable. If you paved a whole driveway with cold mix, the tires of your car would sink in and tear it apart on a hot summer day.
Use Cold Mix For:
Hot mix is incredibly cheap when bought in bulk (around $100-$130 a ton). Cold mix is incredibly expensive when bought in bags. A 50lb bag of cold patch costs about $15. Since there are forty 50lb bags in a ton, you are paying $600 a ton for cold patch.
Find out exactly how many 50lb bags of cold patch you need for your repair before you go to the hardware store.
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