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Heavy Equipment Operator

Any individual who operates general heavy construction equipment such as a backhoe, front-loader, or bulldozer.
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General Guidance

  This is an informational resource on hot mix asphalt (HMA). It contains a general overview of all HMA aspects. It is intended to assist those who work with HMA in any way including architects, engineers, contractors, students, and homeowners. Pavement Checklist Pavement Distress Top-Down Cracking References Suggested Reading Asphalt Institute. (2001[1]). HMA Construction. Manual … Read more »


Construction Noise

Noise Basics Healthy humans can hear audible sound with a range of 20 Hz to 20,000 Hz with a maximum intensity at 3,000 Hz. (Hz = Hertz, or cycles per second.) Frequencies below 20 Hz are called “infrasound” and above 20,000 Hz “ultrasound.” The numerical magnitude of a sound typically expressed as sound pressure level … Read more »

Bituminous Surface Treatments_FI

Bituminous Surface Treatments

A bituminous surface treatment (BST), also known as a seal coat or chip seal, is a thin protective wearing surface that is applied to a pavement or base course. BSTs can provide all of the following: A waterproof layer to protect the underlying pavement. Increased skid resistance. A filler for existing cracks or raveled surfaces. … Read more »

Surface Preparation_FI

Surface Preparation

Before a pavement is placed the surface to be paved must be prepared. Adequate surface preparation is essential to long-term pavement performance. Pavements constructed without adequate surface preparation may not meet smoothness specifications, may not bond to the existing pavement (in the case of overlays) or may fail because of inadequate subgrade support. Surface preparation … Read more »

Figure 1: 6-inch ACB layer under 1.5 inches of State Mix IV (Coin Shown is a Quarter)

Asphalt Concrete Base (ACB)

Asphalt concrete base (ACB), also called asphalt treated base (ATB), is a dense-graded HMA with a larger nominal maximum aggregate size (1 inch) intended for use as a base course or binder course (see Figure 1). In addition to site paving benefits, ACB can be advantageous because it can provide: A waterproof barrier to prevent … Read more »

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Segregation in Transport

“Segregation” is a term often used in the HMA industry to describe a number of different phenomena. It’s most general definition comes from Stroup-Gardiner and Brown (2000[1]): “Segregation is a lack of homogeneity in the hot mix asphalt constituents of the in-place mat of such a magnitude that there is a reasonable expectation of accelerated … Read more »

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Full-Depth Reclamation

Although referred to as “full-depth reclamation”, this process is just an extension of the basic CIR principles to the entire HMA pavement depth plus a predetermined depth of the base material. FDR can be used to depths of 300 mm (12 inches) or more but the most typical applications involve depths of between 150 and … Read more »

A pneumatic tire roller compacting chip seal.

Paving Equipment

Stabilizers/Reclaimers A stabilizer/reclaimer is a vehicle with a dual purpose. These machines have a large rotor blade which may be used to cut and pulverize damaged or old pavement, but which also may be used to mix lime, fly ash, or cement into the subbase in order to stabilize poor soils. Milling Machines A top … Read more »

Figure 2: HMA Placement


Mix laydown involves everything used to place the delivered HMA on the desired surface at the desired thickness. The asphalt paver is the principal machine involved in mix laydown and is assisted by the material transfer vehicle (MTV) in some instances. Placement Considerations There are, of course, many considerations to take into account when placing … Read more »

Figure 8. Milled road showing complete removal of the HMA overlay, which exposes the PCC slabs beneath.

Existing Surface Preparation for Overlays

Overlays (either structural or non-structural) make up a large portion of the roadway paving done today. The degree of surface preparation for an overlay is dependent on the condition and type of the existing pavement. Generally, the existing pavement should be structurally sound, level, clean and capable of bonding to the overlay. To meet these … Read more »

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