What is HMA in asphalt?

Hot mix asphalt (HMA) is known by many different names, such as hot mix, asphalt concrete, asphalt or blacktop. It is a combination of stone, sand or gravel bound together by asphalt cement. After it is mixed at a high temperature, laid and compacted, the result is an improved driving surface for the traveling public.

What does HMA stand for in asphalt?

Asphalt pavement refers to any paved road surfaced with asphalt. Hot Mix Asphalt (HMA) is a combination of approximately 95% stone, sand, or gravel bound together by asphalt cement, a product of crude oil. Asphalt cement is heated aggregate, combined, and mixed with the aggregate at an HMA facility.

What is HMA base?

Definition of HMA. In simple terms…: A mixture of asphalt binder and. graded mineral aggregate, mixed at. an elevated temperature and.

What is Type A HMA?

Type A hot mix requires that at least 90% of the coarse aggregate and 70% of Fine aggregate used contains crushed particles while Type B hot mix only requires 25% and 20% respectively.

What is HMA overlay?

Hot Mix Asphalt (HMA) Overlay involves a composition of asphalt concrete and aggregate. It is used to treat poor pavement conditions when Slurry Seal, Microsurfacing, or Cape Seal treatments are not suitable. The overlay provides a restored surface which is smooth and can withstand heavy traffic.

How an Asphalt Plant Works

What is overlay in pavement?

An overlay is any operation that consists of laying either Portland Cement Concrete (PCC) or Hot Mix Asphalt (HMA) over an existing pavement structure. This is different than a total replacement of the structure, and is typically done when there is only minor to modest damage to the existing pavement structure.

How long will an asphalt overlay last?

If an overlay is desired, there has to be an expectation of the customer that this method is not as long-lasting as a full removal and replacement. A 15-20 year life on a removal and replacement is common, whereas an overlay may last a shorter time, about 10-15 years. Again, this will vary with soil type.

What is the difference between HMA and SMA?

SMA is generally more expensive than a typical dense-graded HMA because it requires more durable aggregates, higher asphalt content, modified asphalt binder and fibers. In the right situations it is cost-effective because of its increased rut resistance and improved durability.

What is the density of HMA?

The density of the compacted mix is its unit weight, or the weight of a specific volume of mix. For compacted HMA, this is approximately 145 pounds per cubic foot. Density is particularly important because high density of the finished pavement is essential for long term pavement performance.

What is 19mm asphalt?

Asphalt Paving ‐ 19mm Binder Course

19mm Binder Course is applied in one layer, is as strong as regular base and has a sufficient amount of liquid asphalt to roll into a very durable surface. The difference is that the texture is coarser than 9.5mm Wearing Course.

What is HMA mix design?

HMA mix design is the process of determining what aggregate to use, what asphalt binder to use and what the optimum combination of these two ingredients ought to be. There are several different methods used to go about this process, of which the Superpave, Marshall and Hveem methods are the most common.

What is 6F asphalt?

There are many different types of asphalt used for paving. The most common are Binder and 7F fine topcoat. However, a new trend in commercial paving is to use what is called a 6F material which is a combination of the Binder and 7F fine topcoat. Contact us today to discuss your commercial asphalt paving needs.

What is hot mix bitumen?

Warm mix asphalt (also generally known as WMA) is a name given to a group of technologies that have the common purpose of reducing the viscosity of the asphalt binders (Abbas and Ali, 2011). From: Asphalt Materials Science and Technology, 2016.

How hot is Hotmix?

As mentioned previously, hot mix asphalt is a type of asphalt that is mixed when the bitumen binder is heated to high temperature, usually around 150-175 degrees Celsius.

What is hot mix design?

HMA mix design is the process of determining what aggregate to use, what asphalt binder to use and what the optimum combination of these two ingredients ought to be.

What is warm mix asphalt used for?

Warm Mix Asphalt (WMA) is the generic term for a variety of technologies that allow producers of Hot Mix Asphalt (HMA) pavement material to lower temperatures at which the material is mixed and placed on the road. It is a proven a technology that can: Reduce paving costs. Extend the paving season.

How is HMA calculated?

First, calculate two WMAs: one with the specified number of periods and one with half the specified number of periods. Second, calculate the raw (non-smoothed) Hull Moving Average. Third, smooth the raw HMA with another WMA, this one with the square root of the specified number of periods.

What is PS in asphalt?

Pba = absorbed asphalt, percent by weight of aggregate. Ps = aggregate, percent by total weight of mixture.

What is GMM in asphalt?

The theoretical maximum specific gravity (Gmm) of a HMA mixture is the specific gravity excluding air voids. Thus, theoretically, if all the air voids were eliminated from an HMA sample, the combined specific gravity of the remaining aggregate and asphalt binder would be the theoretical maximum specific gravity.

What is the percentage of bitumen in DBM?

A bituminous mixture is composed of approximately 95% by weight, or 80% by volume, mineral aggregate.

What does SMA in asphalt stand for?

Stone Mastic Asphalt (SMA) is a gap-graded mix laid between 30mm and 40mm thickness. It may be manufactured using a polymer modified binder (PMB), giving the aggregate skeleton additional strength.

Are there different grades of asphalt?

There are three different grades available in asphalt. The grades available are I-2, also known as base; I-5, known as top ;and the I-4 or commercial top grades. The difference in the tree grades are that the I-2 or base consists of ¾ inches of stone. The base grade is generally used in corn stabilizing level.

Can you put a thin layer of asphalt over old asphalt?

An overlay or resurface can be used on an asphalt driveway, parking lot, or road way. It consists of installing a new layer of asphalt over the existing asphalt and grinding at the transitions (i.e. sidewalks, garages, drains, curbs, or other asphalt points).

How thick should asphalt overlay be?

How Thick Should an Asphalt Overlay Be? A conventional asphalt overlay is at least 2 inches thick. This will vary based on the damage to the existing asphalt surface, however. The more damage there is to the existing asphalt, the thicker the overlay will need to be.

How thick is a typical asphalt overlay?

A conventional overlay is at least 1.5 inches thick, while a thin overlay is less than 1.5 inches thick.