It's not difficult to see why asphalt is such a popular material for residential driveways, with its durability and resistance to the pressures of weather and time providing many years of use. However, asphalt is not invulnerable, and the same potholes you see on public asphalt roads can appear on your driveway over time.
Luckily, asphalt is a relatively easy driveway material to repair, and potholes, cracks and pits can be repaired with commercially available asphalt patching mixes. However, choosing the right kind of asphalt mix for your needs can save you a lot of time and expense and markedly increase the durability of the repair job. Asphalt patching mixes can generally be divided into two categories; hot mixes and cold mixes.
What are the advantages and disadvantages of using hot mix asphalt?
When you see workers repairing or resurfacing public roads, they will almost always be using hot mix asphalt, which is kept in a insulated tank heated with fire tubes or liquid heat transfer systems. Hot mix asphalt holds a number of advantages over cold mix:
- Ease of working -- The bitumen binder which holds the aggregates and sands in asphalt together flows much more easily when hot, making asphalt application much quicker and easier, particularly over large areas.
- Choices of asphalt -- Since large commercial and industrial projects generally favour hot mix, a wide variety of different hot asphalt formulations have been created to meet the varying needs of clients. For example, porous asphalts are available to increase water drainage and prevent standing water on your driveway, while mastic asphalt has excellent friction and anti-skid properties.
Unfortunately, it also has some significant disadvantages:
- Cost -- Hot mix asphalt must be kept at high temperatures to be workable. As such, you will need specialised equipment to store your asphalt at a suitable temperature prior to laying, and the fuel costs associated with keeping an asphalt tank hot can be substantial. For this reason, the vast majority of hot asphalt repairs must be done by professional services with suitable equipment and training, further increasing potential costs.
- Dependence on weather -- Hot asphalt adheres more readily to hot or warm ground, and excessive moisture in the soil or air will impinge the binding process and cause your repairs to fail much more quickly. Hot asphalt is therefore almost always laid in summer.
- Economy of scale -- If your driveway requires extensive repairs or full resurfacing, using hot asphalt makes economic sense. When it comes to smaller repair jobs, however, the extra costs associated with hot mix generally far outstrip the benefits.
What are the advantages and disadvantages of using cold mix asphalt?
Unlike hot mix asphalt, cold mixes do not need to be kept hot to be workable, and are often used to effect smaller repairs such as pothole filling. Cold mixes have the following advantages:
- Cost -- Cold mix asphalt does not need to be kept warm, and can be stored in the container it is sold in until repairs begin (be careful that the container remains airtight and undamaged, as cold mix asphalt starts to cure and harden as soon as it is exposed to air). As such, fuel costs for heating are negated, and you will also save money on equipment hire or purchase.
- Safety -- Using cold mixes eliminates the dangers of burns sustained from hot asphalt and heating equipment malfunction, making it much safer to use, particularly for homeowners who choose to repair their driveways themselves.
- Winter use -- While cold mixes react to moisture about as poorly as hot mixes, they do not require warm earth or underlay to adhere effectively, and can be laid on dry days throughout the year.
As for disadvantages:
- Lack of durability -- Traditional cold mix asphalt is not as durable as hot mix, and is often used to make temporary repairs over the winter that can be replaced with hot asphalt in summer. Modern, polymer-based cold mix asphalts are far more durable and rival their hot mix counterparts, but these tend to be significantly more expensive.
- Difficulty working -- Cold asphalt does not flow as easily as hot asphalt, and working with it can be difficult, especially when it comes to finishing and creating a smooth surface.
- Curing -- Cold mixes generally take much longer to cure and dry than hot mixes, particularly in cold weather, and you may have to avoid recently-repaired patches of driveway for some time.
Talk to a professional for assistance with driveway resurfacing.