Asphalt base

The asphalt layers in a flexible pavement consist of the asphalt base, the binder course and the surface layer or wearing course. 

The asphalt base is the first and most important layer of a flexible pavement, constructed over the unbound or hydraulically bound base. Together with the other overlying asphalt 

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For low slope commercial roofing, bituminous-based roof coverings are the most common systems in the United States. Asphalt-based materials predominate over coal-tar based materials in these systems. For residential roofing materials, various types of roofing products, including asphalt, wood, and tile, ate used for both new constmction and reroofing. 

Three types of asphalt-based roofing materials are used in the membrane roofing market built-up roofing (BUR), modified bitumen membranes, and mopping asphalt. BUR represents about 33% of the membrane roofing market and modified bitumen has about 16% of the total market. 

Asphalt- based Applicable Applicable Applicable contaminant may act as a binding agent Applicable if waste is first neutralized Not applicable Not applicable... 

Cresylic acid is a commercial mixture of phenolic compounds including phenol, cresols, and xylenols. This mixture varies widely according to its source. Properties of phenol, cresols, and xylenols are shown in Table 4-5 Cresylic acid constitutes part of the oxygen compounds found in crudes that are concentrated in the naphtha fraction obtained principally from naphthenic and asphaltic-based crudes. Phenolic compounds, which are weak acids, are extracted with relatively strong aqueous caustic solutions. 

In pipelining, the trend is towards all-welded steel for long lines, and since the wall thickness is less than that of cast iron, protection is the more important. Many types of coating are used, from thick concrete to thin paint films, and each has its own particular suitability, but the majority of pipelines throughout the world today are coated with hot-applied coal tar or petroleum asphalt-base-filled pipeline enamels, into which reinforcing wraps, such as glass fibre are applied. 

The field performance of the asphalt-base pipeline enamels was, at one time, erratic, probably because the material had been drawn from varying sources, without a close specification being used. The plasticised coal-tar-base enamel to the American Water Works Association Specification C-203 thus gained some favour in major pipelining organisations. 

Readdy, Reactivity of Minol II Explosive with Asphalt-Based Coatings of Bomb Cavities , PATM 1944 (Oct 1970) 36) J. Harris, Ther-... 

The composition of crude oil may vary with the location and age of an oil field, and may even be depth dependent within an individual well or reservoir. Crudes are commonly classified according to their respective distillation residue, which reflects the relative contents of three basic hydrocarbon structural types paraffins, naphthenes, and aromatics. About 85% of all crude oils can be classified as either asphalt based, paraffin based, or mixed based. Asphalt-based crudes contain little paraffin wax and an asphaltic residue (predominantly condensed aromatics). Sulfur, oxygen, and nitrogen contents are often relatively higher in asphalt-based crude in comparison with paraffin-based crudes, which contain little to no asphaltic materials. Mixed-based crude contains considerable amounts of both wax and asphalt. Representative crude oils and their respective composition in respect to paraffins, naphthenes, and aromatics are shown in Figure 4.1. 

A widely used classification of petroleum distinguishes between crude oils either on a paraffin base or on an asphalt base and arose because paraffin wax separates from some crude oils on cooling, whereas other oils show no separation of paraffin wax on cooling. The terms paraffin base and asphalt base were introduced and have remained in common use (van Nes and van Westen, 1951). 

The presence of paraffin wax is usually reflected in the paraffinic nature of the constituent fractions, and a high asphaltic content corresponds with the naphthenic properties of the fractions. As a result, the misconception has arisen that paraffin-base crude oils consist mainly of paraffins and asphalt-base crude oils mainly of cyclic (or naphthenic) hydrocarbons. In addition to paraffin- and asphalt-base oils, a mixed base had to be introduced for those oils that leave a mixture of bitumen and paraffin wax as a residue by nondestructive distillation. 

Uses/Sources. Asphalt fumes arise from asphalt used for road construction, roofing, and coating of construction materials and in association with the production of asphalt from petroleum in asphalt-based paints... 

All types of crudes have been used in the production of spray oils. On the West Coast the asphaltic base crudes occurring locally have been generally used, while oils derived from mixed base stocks are now most commonly used east of the Rockies. 

Petroleum crude oils, which are divided for the purposes of conventional classification into three main types—asphalt (or naphthenic)-base, paraffin-base, and mixed-base—contain varying amounts of hydrocarbons which readily solidify and are identified as wax. The asphalt-base crudes may contain only a trace of wax, while the wax content of the paraffin-base crudes and the mixed-base crudes may be as high as 15% or higher (73). Crude oils with a wax content as high as 35% are known. 

Ref Dr L. Deffet, Bruxelles private communication, March 10, 1954 ALT. A solid propellant for rockets K perchlorate 76.5 asphalt base fuel 23.5%. 

The bottoms of the CD, also known as atmospheric residue, are charged to a second fired heater where the typical outlet temperature is about 750-775°F. From the second heater, the atmospheric residue is sent to a vacuum tower. Steam ejectors are used to create the vacuum so that the absolute pressure can be as low as 30-40 mm Hg (about 7.0 psia). The vacuum permits hydrocarbons to be vaporized at temperatures below their normal boiling point. Thus, the fractions with normal boiling points above 650°F can be separated by vacuum distillation without causing thermal cracking. In this example (Fig. 18.14), the distillate is condensed into two sections and withdrawn as two sidestreams. The two side-streams are combined to form cracking feedstocks vacuum gas oil (VGO) and asphalt base stock. 

Related Calculations. Use the method given here when making combustion calculations for any type of fuel oil—paraffin-base, asphalt-base, Bunker C, No. 2, 3, 4, or 5—from any source, domestic or foreign, in any type of furnace—boiler, heater, process, or waste-heat. When the air used for combustion contains moisture, as is usually true, this moisture is added to the combustion-formed moisture appearing in the products of combustion. Thus, for 80°F air of 60 percent relative humidity, the moisture content is 0.013 lb per pound of dry air. This amount appears in the products of combustion for each pound of air used and is a commonly assumed standard in combustion calculations. 

For the low-temperature experiment the rate of extension apparatus, as described by Hajek (25) and Haas (26), was used to determine the stiffness of test specimen of SA binder based concrete mixes at — 10° and — 25°C. The asphalt cements chosen were 40-50, 85-100, and 300-400 penetration grade to cover the entire range as well as to ensure that if a difference in properties did exist, it would be noticeable. The other test variables included temperature susceptibility (obtained by using asphalts based on crude oils from various sources), SA ratio, and binder content. 

The earliest binders were those which were already well known, either in adhesives or paints. They included corn syrup, glycerol, ethylene glycol and dextrose (all dispersed in water), asphalt-based varnish (in naphtha), and silicone varnish (in xylene). The range of binders which has been studied has since been extended enormously, to include lacquers, polymers, soluble salts, fused salts, fusible oxides and fluorides, ceramics and metals, and a number are listed in Table 11,1. 

If the residue which remains after distillation is a waxlike solid consisting largely of paraffin hydrocarbons the crude is designated as paraffin base. If the residue is a black pitchlike solid the crude is called asphalt base, Pennsylvania crude has a paraffin base whereas California oils are for the most part asphalt base. Often a clear-cut distinction cannot be made and the crude is described as being mixed base oil. Most Mid-Continent crudes are of this tyrpe. 

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