Asphalt, composition

However, for the past 30 years fractional separation has been the basis for most asphalt composition analysis (Fig. 10). The separation methods that have been used divide asphalt into operationally defined fractions. Four types of asphalt separation procedures are now in use ( /) chemical precipitation in which / -pentane separation of asphaltenes is foUowed by chemical precipitation of other fractions with sulfuric acid of increasing concentration (ASTM D2006) (2) solvent fractionation separation of an "asphaltene" fraction by the use of 1-butanol foUowed by dissolution of the 1-butanol solubles in... 

In order to relate quantitatively certain flow properties to asphalt composition, Hardman and Hughes (32) found it necessary to introduce viscosity of the petrolenes as a controlling variable, in addition to the weight per cent asphaltenes and the aromatic... 

Early in the development of solid propellant, the asphalt composites were found to have poor physical properties, such as cracking under normal temperature cycling, poor tensile characteristics, etc. They were replaced with the elastomeric polymers which have become the present-day binders. The first of these was Thiokol rubber, a polysulfide rubber, whichgives the propellant with good physical properties. The presence of the sulfur atom in the Thiokol rubber decreases the performance compared to a CHO polymer thus the most frequently used binders are polyurethane, polybutadiene acrylic acid (PBAA), epoxy resin, etc. The choice of the latter binders is made with regard to physical properties rather than performance. 

The form of the dissolved sulfur has not been characterized properly yet. While stable at ambient temperatures, a substantial amount can be converted to crystalline sulfur at elevated temperatures or by solvent separation. This observation led to the development of a rapid liquid chromatography method to determine elemental sulfur in SA binders. The procedure which has been described previously by Cassidy (17) is based on gel permeation principle and uses a Styragel column and a uv detector. Results showed that 2-14% of the elemental sulfur added reacted chemically with the asphalt. Petrossi (18) and Lee (19), who determined free sulfur by extraction with sodium sulfite followed by titration with iodine, calculated a higher percent of bonded sulfur in sulfur-asphalt compositions. The observed differences are most likely caused by variations in the asphalt composition with regard to polar aromatics and naphthene components as well as by reaction temperature and contact time. 

These analyses support a significant series of inferences with respect to the sources of asphalt. DiflEerences in asphalt composition, mineral color, and especially sulfur content of the bitumen indicate that lowland and highland asphalts were not derived from the same raw materials. Mesopotamian asphalts simply do not match those found in the usually earlier settlements along the Tigris tributaries. Presumably new sources upstream along the Euphrates were used. They would certainly be more convenient than overland shipment from the east. Lesser diflEerences... 

HEPTANE Asphaltenes (C7). Asphaltenes were prepared according to References 20, 21 in boiling heptane with a ratio of one part by weight of residue to thirty parts by volume of solvent (for example 1 g/30 mL). In the United States there is a proposed method for asphalt composition analysis (22) using n-heptane and a solvent/ charge of 100 (v) l (w). 

Use Filtration clarifying and decolorizing insulation absorbent mild abrasive drilling-mud thickener extender in paints, rubber, and plastic products ceramics paper coating anticaking agent in fertilizers asphalt compositions chromatography refractories acid-proof liners catalyst carrier. 

Use Ore flotation, roofing compositions, paints and varnishes, softener in plastics and rubber processing, tar soaps, deKhotinsky cement, asphaltic compositions, marine preservative, medicine (cough syrups), laboratory reagent. 

Previous investigators have drawn attention to the beneficial effect of lime when added in small quantities to asphaltic bitumen. The lime helps retard oxidative hardening (13) and reduces the tendency towards water-stripping (4,11,12). Most asphalts are slightly acidic because of the presence of phenolic or carboxylic substituents and would therefore react with basic oxides to form insoluble salts. For example, Fromm (10) has described the use of iron salts of naphthenic acids as adhesion promoters to improve the water resistance of asphalt concretes. This promising approach is now undergoing commercial trials. The literature also describes methods of chemically modifying asphalt with maleic anhydride or acrylic acid (14), sulfur trioxide (15), sulfur dioxide (16), acetyl sulfate (17-21), and sulfuric acid (20). (For a recent review of the interfacial phenomena in asphaltic compositions see Ref. 4.)... 

Aggregate Suitability Evaluation. As indicated earlier, most of the mixes studied were made with medium-coarse sand. However, a number of mixes were prepared to explore the range of aggregate gradations which may benefit from sulfur addition to asphalt compositions. The gradations in Table I cover materials from fine blow sands to coarse pit... 

The performance of the above pavements is being evaluated, and although the results are promising, a longer test period is necessary before conclusive results are obtained. A further field trial will be conducted at McLean, Saskatchwan during 1974. This trial will compare the performance of various sulfur-asphalt compositions and structures with conventional asphalt structures under low temperature conditions. The test road will include appropriate instrumentation. 

Uses Filler for asphalt compositions and roof coatings antibiock agent in plastic film filler in plastics, molding compds., agric., paints, cement, paper, caulks, adhesives, sealants, encapsulants, foods catalyst car-rier/support inert mild abrasive in polishes/cleaners Features Contributes vise, control, reduced settling, reduced VOC requirement... 

HMIS Health 0, Flammability 2, Reactivity 0 Uses Plasticizer, softener, tackifier, processing aid for rubber and plastics raw material for paints and varnishes ore flotation roofing compositions tar soaps asphaltic compositions marine preservative laboratory reagent antidandruff agent in cosmetics plasticizer in food-contact rubber articles for repeated use medicine (cough syrups) Regulatory FDA 21CFR 177.2600... 

The fatigue point depends not only on the asphalt composition and its properties but also on the magnitude of the applied stress, the test temperature and the loading time. 

SEC analysis can be used very effectively in combination with Corbett separation, solvent or supercritical solvent fractionation, and other fractionation procedures for the purpose of understanding asphalt composition and aging. Figure 2 shows chromatograms for an asphalt cut into a 60% top fraction and a 40% bottom fraction by supercritical pentane (15). The top 60% was fractionated into four fractions by supercritical pentane (Figure 3), and the bottom... 

Polymer modified asphalt originated in Europe in the early 1960s. Atactic PP is still used today in asphalt compositions mainly in Europe, Mexico and Asia. A PP copolymer containing 2-10% ethylene is more popular in USA. Thermoplastic block copolymers with styrene end blocks or with a diene midblock like S-B-S and styrene-isoprene-styrene (SIS) and their hydrogenated versions are common modifiers for asphalt [40]. 

The residue from distillation is a black, tarry material called petroleum asphalt. It is used in making roads, for asphalt composition roofing materials, for stabilizing loose soil, and as a binder for coal dust in the manufacture of briquets for use as a fuel. A similar material, hitumen or rock asphalt, is found in Trinidad, Texas, Oklahoma, and other parts of the world, where it presumably has been formed as the residue from the slow distillation of pools of oil. 

PENNGUARD Adhesive/Membrane is a two-component urethane asphalt composition used in the installation of the PENNGUARD Block Lining System. As an adhesive, it serves to bond the PENNGUARD Block to a prepared substrate, and as a membrane, it serves as a moisture and chemical-resistant barrier. TUFCHEM II Membrane is an improved, two component, urethane asphalt based membrane system, that can be used, within its limitations, to protect concrete and steel surfaces from chemical attack and abrasion. 

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