While different types of asphalt may have similar appearances, there are actually several different “mixes” or combinations of materials and processes that asphalt can be made of. These mixes vary so that can professionals can match the mix to local conditions like weather, temperatures, and how much stress the asphalt will be under.
In Central Oregon, asphalt needs to withstand both hot summers and freezing winters, which is why high-quality asphalt mixes and installation are so important in the area. Let’s do a quick rundown of different mixes, how they’re made, and what works best for conditions around Bend Oregon.
Hot Mix Asphalt
Hot mix asphalt is created and heated up to 300 to 500 degrees during preparation. This mix can be more demanding to create and transport – asphalt needs to be kept hot until it is applied – but it also has many advantages. The high heat allows the aggregates (like sand or gravel) to bond very firmly, and the overall mixture is highly durable. Hot mix asphalt also cools down very quickly, so it’s a good idea for fast installations.
The durability of hot mix asphalt makes it a particularly good choice for climates with a lot of temperature changes – it’s a good match for Central Oregon’s summers and winters. The extra durability helps withstand damage from studded tires, and the hot mix is particularly good at allowing contractions and expansions without
Because of these qualities, hot mix asphalt is a good fit for commercial paving in Central Oregon, and is a common recommendation for parking lots and roads. Residential asphalt paving contractors in Central Oregon may also recommend it for driveways and other private projects that need to stand the test of time.
Asphalt can also be identified by performance grade or “PG.” This is a number that specifically refers to the binding chemicals used in the asphalt mix. Different binder combinations can make asphalt more resistant to cold weather, or more durable over time so it doesn’t need to be replaced as often.
PG ratings are especially useful for large commercial projects, because they indicate what precise type of mix is appropriate for specific regions. For example, in Central and Eastern Oregon above 2,500 feet elevation, PG 64-28 is recommended for rural highways, and PG 76-28 is recommended for critical urban highways. These official recommendations are very useful as starting points for what precise asphalt PG level to use in Central Oregon.
The two other common asphalt mixes are warm mix and cold mix. Warm mix asphalt is made at far lower temperatures, which saves lots of energy and expense during production, and it can be placed in a wider range of temperatures. Warm mix asphalt isn’t as durable as hot mix and must be placed carefully to avoid problems, but it’s better for the environment and generally easier to work with. Asphalt services may recommend it for private projects, especially when backed up with a driveway sealcoating to help prevent damage over time. Cold mix asphalt, on the other hand, is typically used only for patching and temporary repairs, and is not designed for long-lasting projects.