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Hot Mix Asphalt: Understanding its Applications, Aggregate Sizes, and Asphalt Grades


The words "hot mix asphalt understanding its applications, aggregate sizes and asphalt grades" overlayed on black asphalt.

As the most popular choice for paving residential roads and parking lots, hot mix asphalt (HMA) is the workhorse of the paving industry. But what exactly is HMA, and how does its composition impact its function? In this post, we'll delve into the world of HMA, exploring its applications, aggregate sizes, and asphalt grades.


What is Hot Mix Asphalt (HMA)?


Hot Mix Asphalt is a combination of approximately 95% stone, sand, or gravel bound together by asphalt cement, a product of crude oil. HMA is mixed at high temperatures (around 300 degrees Fahrenheit) in an asphalt plant and then transported to the job site, hence the name "hot mix." It's best known for its durability, resilience, and flexibility.


Applications of HMA


HMA's various properties make it suitable for a range of applications:


Residential Driveways: HMA's smooth finish enhances the appearance of driveways, and its durability ensures it will stand up to both foot traffic and vehicles.


Parking Lots: The flexibility of HMA allows it to adapt to temperature changes, reducing cracking and maintenance, making it a popular choice for commercial parking lots.


Understanding Aggregate Sizes in HMA


Aggregate is granular stone, gravel or sand that is combined with a binding medium used to form the asphalt. The aggregate size in HMA significantly impacts its properties. There are three primary types of HMA based on aggregate size:


Fine-graded mixes: These mixes have a higher percentage of sand and smaller aggregates. They provide a smooth, tight surface ideal for residential streets and driveways.


Coarse-graded mixes: These mixes contain more large aggregates, making them more durable and suitable for heavy traffic areas like highways and major roads.


Dense-graded mixes: These are a balance between coarse and fine-graded mixes, providing durability and a smooth finish, making them versatile for a range of applications.


Central Coast Paving specializes in fine-graded mixes to make your residential or commercial pavement stand out. Typically a 1/2” aggregate asphalt is used as a structural layer for a driveway and offers a good mix of a smooth finish with a strong larger aggregate structure. Alternatively 3/8” asphalt is used for filling potholes, performing small and thin maintenance surface patches as it consists of smaller aggregate and more sand material for an extremely smooth finish.



Asphalt Grades in HMA


The asphalt binder used in HMA also comes in different grades. Softer asphalts, such as PG 52-28, are used in colder climates, where flexibility is crucial. Harder asphalts, such as PG 76-22, are used in warmer climates or high-traffic areas, where resistance to rutting is necessary. For our local Southern California projects, we use PG 64-10, making it


In conclusion, HMA's versatility, stemming from its varying aggregate sizes and asphalt grades, makes it a go-to choice for a broad range of paving applications. By understanding the different types of HMA and where they're best used, you can make informed decisions for your next paving project.


So, whether you need to pave a commercial parking lot or revamp your property’s driveways, you can trust the Central Coast Paving experts to guide you in the right direction! Contact us at (805) 665-3292 to get started today.

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