Adhesion of asphalt

The adhesion of asphalt to the mineral aggregate is a fundamental property of road asphalt. Once the adhesion deteriorates, the surface becomes unstable and unusable. There is a test method (ASTM D-1191) designed for use on crack and joint sealers that is used primarily to determine whether a jointing material possesses an arbitrary amount of bonding strength at low temperatures where portland cement concrete is being used. 

Sommer (25) claimed that the adhesivity of asphalt to aggregate is improved by adding elemental sulfur and amines having 12-14 carbon atoms. Hughes and Stine (26) indicated that the adhesivity of asphalt to aggregate is improved by adding sulfur and phosphorus sulfides. 

In another invention, a modifier is introduced to increase the adhesion of asphalt/wa-ter emulsions to aggregates. Emulsified asphalt is not so deleterious to the environment but its performance suffers from aggregate delamination. In yet another recent invention, terpene solvent, which is a naturally occurring (but never in this high concentration), biodegradable material, was used to replace the mineral spirits, xylene, trichloroethane, toluene, or methyl ethyl ketone normally used in cutback formulations (cutback asphalt is a dispersion of asphalt in a suitable solvent to reduce viscosity and allow for cold application). The two other patents discuss inventions leading to an improvement of high and low temperature properties of asphalt with no special impact on reduction of solvents used. 

A number of rather tenuous arguments suggest ozone damage to such materials as recording tape, asphalt, and dried milk. However, studies on such subjects are scattered and generally uncorroborated. Some studies even discuss beneficial effects of ozone, such as reduction of corrosion rates in steel and improvement in adhesion of ink to polyethylene films. 

Although they are a relatively small volume product—approximately 75,000 tons produced in 1949 (126)—interest in asphalt emulsion has continued at a high level. Abraham (6) has reviewed the patent literature relative to the types of emulsifying agents used, while commercial practice has been discussed by Day (16). The most common emulsifiers are sodium or potassium soaps of tall oil, abietic acid, or Vinsol resin, or colloidal clays such as bentonite for adhesive base emulsions. Lyttleton and Traxler (53) studied the flow properties of asphalt emulsions, and Traxler (122) has investigated the effect of size distribution of the dispersed particles on emulsion viscosity. A decrease in particle size uniformity was found to be accompanied by a decrease in consistency because particles of various size assume a more loosely packed condition than do those of the same size. 

The versatility of asphalt as an adhesive, sealant, and protectant provided early innovators with a unique material with which to advance their primitive technology. Despite the ravages of thousands of years, the main components are still recognizable. Minerals of course remain largely unchanged. Although bitumen is converted extensively to asphaltenes, many resins and even some hydrocarbons are still extant and available for examination. Often the use to which the asphalt was put is still obvious—but not always. 

Hot asphalt applications had been used for many years in concrete tanks, inner lined with brick for similar service, and also, of course, unlined wood tanks made from timber, and small pickling tanks made by hollowing out cavities in granite blocks. But the use of hot asphalt as a liner for steel tanks had been unsatisfactory due to the erratic cold flow of the asphalt which demonstrated selective adhesion to steel and so would tear and open cracks in the membrane system in the areas of cold flow below the points where it adhered. To overcome this difficulty, a number of inventive persons experimented with the manufacture of asphalt sheet lining materials, similar in form to the sheets of natural rubber, in which the asphalt was compounded with various admixtures, including rubber. These asphaltic compound sheets were then warmed sufficiently to make... 

The annual consumption of asphalt in North America is nearly 30 million metric tons of which 74% is used in road construction, 15% in roofing, and 11% in coatings, adhesives, and miscellaneous applications. At about 10 cents/kg, asphalt is evidently one of the cheapest and most abundant thermoplastics available in the world today. 

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.)... 

Butonal . [BASF AG] Butadiene/sty-rene polymer dispersions binders for prod, of adhesives, treatment of asphalt. 

Caresiiie 2000. [BA AG] Bentazon, ist troturon, dichloqntq) binders for >1 of adhesives, treatment of asphalt. 

Evaluation of Different Techniques for Adhesive Properties of Asphalt-Filler Systems at Interfacial Region... 

It is assumed that contact between mineral fines and asphalts results in migration of polar organic asphalt molecules to polar sites on mineral surfaces. This aggregate induced interaction results in changes in asphalt microstructures. Currently, no standard binder test is in use to determine the aggregate-induced effects of asphalt microstructure on the rheological properties of asphalt binders (adhesion), nor is there a mixture test that determines the contribution of these physicochemical effects on the properties of asphalt-aggregate mixtures. 

In addition to widespread use as a blend in asphalt/rubber sealants for roofing and other construction applications, reclaim rubber adhesives have been used as an insulation adhesive, as a pipe wrap adhesive, and as an ingredient in some pressure sensitive adhesives. Of interest is the fact that virtually every telephone installation in the United States before 1985 that required a cable splice used a reclaim rubber adhesive. 

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