Liquid Asphalt

Asphalt pavement is one of America’s building blocks. The United States has more than 2 million miles of paved roads and highways, and 94% of those are surfaced with asphalt. Asphalt cement is the binder, or glue, that holds the various components, including aggregates, recycled materials, fibers, and other additives, in an asphalt pavement together. Heartland Asphalt Materials typically produces PG 64-22 and PG 58-28; however, other non-polymer modified PG graded asphalts can be easily produced at our facility.

See “asphalt binder.”

An asphalt emulsion consists of three basic ingredients: asphalt, water, and an emulsifying agent. In the same process, these components are introduced into a mechanism known as a colloid mill, which shears the asphalt into tiny droplets. Particles of asphalt cement become coated with a mild soap solution to form a homogenous water based asphalt. The emulsifier, which is a surface-active agent, keeps the asphalt droplets in a stable suspension and controls the breaking time. Emulsions can be either anionic (negatively charged) or cationic (positively charged), and are further classified into slow setting, medium setting and rapid setting categories. The type of emulsion to choose is determined by its intended purpose. Since emulsions are water based, they are environmentally friendly, but are subject to temperature changes. Emulsions are used for many applications in fog seals, chip seals, slurry seals, pavement repair, and in construction.

Cutback Asphalt is manufactured by blending asphalt cement with a petroleum solvent. There are three major types of Cutback Asphalt based on the relative evaporation of the solvent: Rapid-Curing (RC), Medium-Curing (MC) and Slow-Curing (SC). Rapid-Curing Cutback Asphalt is used primarily for surface treatments and tack coat. Polymer Modified Rapid-Curing Cutback Asphalt is used only for surface treatments. Medium-Curing Cutback Asphalt is typically used for prime coat, surface treatments, and stockpile patching mixes. Heartland Asphalt Materials produces MC-30 and MC-70 (typically used as prime coat and dust control agents), MC-250 and MC-800 (typically used in a chip seal pavement surface treatment), and MC-3000 (typically used in a chip seal pavement surface treatment).

Colpatch™ is an easy to use high-performance patching material, suitable for patching potholes, filling utility cuts, and repairing damaged asphalt and concrete pavements. Colpatch™ comes ready to use and requires no heating, mixing, or tack coat. Heartland Asphalt Materials produces the specially-designed asphalt binder for the Colpatch™ material.

Colpatch™ can be stockpiled for up to a year** and is workable in temperatures down to approximately 10°F.

Fog Seal is a specifically designed asphalt emulsion used on an existing “sound” paved road surface. It can be used on hot mix asphalt as a pavement rejuvenator, thus extending the life of the pavement. Fog seals are one of the most cost effective pavement preservation treatments available.

FasBlack is a bituminous fog seal especially designed to improve the service life of road surfaces. It uses an asphalt emulsion and has many of the same characteristics as rapid setting emulsions.  FasBlack leaves the road blacker longer than a conventional fog seal, providing extended UVR protection to the paved surface.

Tack coat (also known as bond coat) is a light application of asphalt emulsion between hot mix asphalt layers designed to create a strong adhesive bond without slippage. Heavier applications may be used under porous layers or around patches where it also functions as a seal coat.

See “Tack Coat.”

Without tack coat the asphalt layers in a road way may separate, or delaminate, which reduces the structural integrity of the road and may also allow water to penetrate the structure.

Non-tracking tack performs similar functions as a conventional tack coat, except it breaks in minutes and greatly reduces tracking to surrounding surfaces. It also provides waterproofing properties which safeguard the substrate and base layers, while ensuring good adhesion of overlays to the existing surface. Non-tracking tack is especially well-suited for urban areas with adjacent concrete sidewalks or upscale residential areas with decorative pavement surfaces, which may be damaged when conventional tack coats are used. This product is known in Missouri and Arkansas as SS1VH, in Illinois as NTEA, in Kentucky as non-tracking tack, and in Tennessee as TTT-1.

Prime coats protect the integrity of the granular base during construction and help reduce dust. In the case of a base which is to be covered with a thin hot mix layer or a chip seal for a low volume roadway, priming ensures a good bond between the surface treatment and the underlying surface which otherwise would have a tendency to separate, or delaminate.

Asphalt emulsion does not require a petroleum solvent to make it liquid and in most cases asphalt emulsions can be used without additional heat. Both of these factors contribute to energy savings. Additionally, asphalt emulsions offer flexibility in their application since they offer the end-user a variety of characteristics not found in other paving and maintenance materials. Asphalt emulsions are environmentally friendly. There are little or no hydrocarbon emissions created with their use.

Asphalt emulsions are classified into three categories; anionic, cationic, or nonionic. The anionic and cationic classes refer to the electrical charges surrounding the asphalt particles. The absence of the letter “C” denotes anionic emulsions. Asphalt emulsions are further classified on the basis of how quickly they coalesce, or revert to asphalt cement. The terms RS (Rapid Set), MS (Medium Set), SS (slow set), and QS (Quick Set) have been adopted to simplify and standardize this classification. Additionally, trailing numbers are used to delineate the relative viscosity of the emulsion and the letters “h” and “s” indicate whether a hard or soft base asphalt is used to make the asphalt emulsions. Thus, a CSS-1h is a cationic slow set emulsion with a relatively low asphalt emulsion viscosity made with a hard base asphalt.

The main components of the emulsion are asphalt (bitumen) and water. Emulsions come in different grades but typically contain between 55 and 75% asphalt. In addition to the asphalt and water, asphalt emulsions contain 0.1-2% of an emulsifier or ‘soap’ which functions to stabilize the emulsion. These soaps are similar in nature to the soaps and detergents used in household cleaning and personal care. The asphalt emulsions may also contain minor amounts (< 1%) of other ingredients such as pH (acidity) regulators, and viscosity regulators.

When asphalt emulsion is mixed with the aggregates used in road construction, the emulsion is destabilized and the droplets of asphalt fuse together providing a strong adhesive bond to ‘glue’ the aggregates together. Water evaporates while the emulsifiers remain behind in the asphalt where they provide a valuable function in helping the asphalt stick to the aggregate.

The PG stands for Performance Graded. The PG System for rating asphalt binders is the result of the Strategic Highway Research Program (SHRP), authorized in 1987. This new method for selecting the appropriate binder for pavement performance considers rutting, fatigue cracking, and low temperature cracking. The standard notation for PG binder is PG XX-YY where XX is the average seven-day maximum pavement design temperature and YY is the minimum pavement design temperature.

See “PG binder.”