Asphalt blown

Air-blown asphalts, more resistant to weather and changes ia temperature than the types mentioned previously are produced by batch and continuous methods. Air-blown asphalts, of diverse viscosities and flow properties with added fillers, polymers, solvents, and ia water emulsions, provide products for many appHcations ia the roofing industry. 

Many investigations of relationships between composition and properties take into account only the concentration of the asphaltenes, independendy of any quality criterion. However, a distinction should be made between the asphaltenes which occur in straight mn asphalts and those which occur in blown asphalts. Remembering that asphaltenes are a solubiUty class rather than a distinct chemical class means that vast differences occur in the make-up of this fraction when it is produced by different processes. 

Built-up roofing constitutes several pHes of a saturated roofing felt (low melt, flexible asphalt saturant) with each ply mopped in place and the stmcture covered by air-blown asphalts of from 60° to 105°C softening point, with the hardness selected depending primarily on roof slope. These roofs are usually surfaced with mineral aggregates. 

Neutralized sulfonated asphalt (i.e., salts of sulfonated asphalt and their blends with materials such as Gilsonite, blown asphalt, lignite, and mixtures of the latter compounds) are commonly used as additives in drilling fluids. These additives, however, cause some foaming in water or water-based fluids. Furthermore, these additives are only partially soluble in the fluids. Therefore, liquid additives have been developed to overcome some of the problems associated with the use of dry additives. On the other hand, with liquid compositions containing polyglycols, stability problems can arise. Stable compositions can be obtained by special methods of preparation [1407]. In particular first the viscosifier is mixed with water, then the polyglycol, and finally the sulfonated asphalt is added. 

Low-gravity materials used primarily to reduce cost. e.g.. blown asphalt, wood floe. etc., in rubber and plastic mixes, in this sense, there is no clear distinction between a diluent and an extender. 

Air-blown asphalt asphalt produced by blowing air through residua at elevated... 

Blown asphalt the asphalt prepared by air blowing a residuum (q.v.) or an asphalt (q.v.). 

Samples. Two straight-reduced asphalts from Romashkino-type (29° API gravity) crude petroleum, 100 penetration (SR-100) and 125 penetration (SR-125), and three air-blown asphalts of different degrees of oxidation, 100, 50, and 25 penetration (AB-100, AB-50, and AB-25) were investigated. The air-blown asphalts were derived from SR-125. The properties of the asphalts are given in Table I. 

The increase in asphaltenes in air-blown asphalts results from chemical reactions occurring in the asphalt upon oxidation, resulting in the formation of molecular aggregates. 

Two types of asphalt were used blown asphalt and emulsified asphalt. Blown asphalt is asphalt stock that has been heated at temperatures from 200°-300°C and had air blown through it. The process is one of dehydrogenation and polymerization, resulting in a product that is thermally more stable. We used a blown asphalt provided by the Exxon Corp. because it most closely resembles Mexphalt R 90/40 (Shell Oil Co.), the blown asphalt used most in Europe. Mexphalt R 90/40 is not available in the U.S., but differs chiefly in being somewhat softer than the asphalt from the Exxon Corp. 

Emulsified asphalt was also investigated. Type RS-2 was chosen, as this type is common and has been tested at Oak Ridge (9). Our material was 69% asphalt, 28% water, and 3% tall oil. Even after evaporation of the water, the material is still much softer than blown asphalt, as shown in Figure 6. 

Blown asphalt is more stable mechanically, but requires higher operating temperatures than emulsified asphalt. Currently, blown asphalt is the favorite for waste fixation purposes in countries using this method. 

Samples of blown asphalt containing high amounts of sludge retain their integrity and become very hard when irradiated (Figure 9). All samples made with blown asphalt were irradiated at 6 X 10 rads/hr at 32°C. With 10-20% sludge, the volume increase was / 75%. At 40-60%... 

Figure 6. Variation of viscosity with shear rate (T = 25° C). = 80-100 conventional asphalt (linear). = 20-80 S/A emulsion with 80-100 asphalt. = 40-50 asphalt (linear). = 30-70 S/A emulsion with 80-100 asphalt. = 20-30 blown asphalt (not linear).

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