What is HMA surface course?

What is HMA surface course?

The surface course (typically an HMA layer) is the stiffest (as measured by resilient modulus) and contributes the most to pavement strength. The underlying layers are less stiff but are still important to pavement strength as well as drainage and frost protection.

What is surface course in asphalt?

Asphalt Surface Course refers to an aggregate, sand, and asphalt cement mixture used as the final surface course placed in a lift (often above the intermediate asphalt pavement course), in a roadway application, driveways, parking lots, and trails.

What is the aggregate in asphalt?

Aggregates (or mineral aggregates) are hard, inert materials such as sand, gravel, crushed stone, slag, or rock dust. Properly selected and graded aggregates are mixed with the cement- ing medium asphalt to form pavements. Aggregates are the principal load-supporting components of an Asphalt Concrete pavement.

What is HMA in paving?

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 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.

What is aggregate surface course?

208-2.2 CRUSHED AGGREGATE SURFACE COURSE. The aggregates shall consist of both fine and coarse fragments of crushed stone or crushed gravel mixed or blended with sand, screenings, or other similar approved materials.

What is aggregate base course?

Aggregate Base Course often referred simply as ABC, has certain desirable properties. Base Course in pavements refers to the sub-layer material of an asphalt roadway and is placed directly on top of the undisturbed soil (Sub-Grade) so as to provide a foundation to support the top layers of the pavement.

What is the best aggregate for asphalt?

The best coarse aggregates for asphalt tend to be crushed stone, crushed gravel or crushed slag, which are generally strong, irregular/angular in shape, with roughened surface texture.

What is overlaying in road construction?

An overlay or resurface project involves the application of approximately 2 inches of asphalt concrete to the existing surface or pavement of the road to help prolong the life of the road. Overlay or resurface treated roads might undergo repairs to fix cracks and potholes.

What is surface course in road construction?

The wearing course is the upper layer in roadway, airfield, and dockyard construction. The term ‘surface course’ is sometimes used, however this term is slightly different as it can be used to describe very thin surface layers such as chip seal. In rigid pavements the upper layer is a portland cement concrete slab.

Which is coarse aggregate?

Coarse aggregates are any particles greater than 0.19 inch, but generally range between 3/8 and 1.5 inches in diameter. Gravels constitute the majority of coarse aggregate used in concrete with crushed stone making up most of the remainder.

What is HMA type A?

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.

Are there different grades of asphalt?

When it comes to asphalt, you have many choices as homeowners. 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.

What is the surface course?

The surface course is the very last layer of road construction (prior to markings). It is the part of a road that endures direct contact with traffic. Occasionally, you will encounter materials, such as self-binding gravel, that disrupt this list.