Viscosity asphalt

GretzRH (1980) Mineral fines effect on asphalt viscosity (Report No. 164). Washington State Department of Transportation, Olympia, Washington, DC, p 82... 

The apparatus consists of a paddle that rotates at 100 rpm and measures viscosity in cen-tipoise. The preset temperature and rotational speed allow for an automated and consistent determination of an emulsified asphalt viscosity within a short time. 

Griffin R.L.,T.K. Miles, C.J. Penther, and W.C. Simpson. 1957. Sliding Plate Microviscometer for Rapid Measurement of Asphalt Viscosity in Absolute Units. Emeryville, CA Shell Development Co. 

Studies have shown that increases in asphalt viscosity with oxidation can be correlated with increases in carbonyl formation (20). Almost certainly this hardening results from hydrogen bonding between heteroatom groups in asphaltene molecules and also between polar aromatics, which then may become asphaltenes (66-69). This association strongly impacts attempts to measure molecular size by SEC or colligative properties. 

The viscosity data for Mexican crude Peace River bitumen , Athabasca bitumen California crude all show that the viscosity of oil and asphalt blends Increase with the concentration of asphaltenes. AItgelt and Harle also studied the effect of asphaltene on asphalt viscosity. They found asphaltenes to form aggregates In solution. The degree of which was found to depend upon structure, molecular weight and concentration of the asphaltenes and the solvent power. They concluded that the viscosity of asphaltene Is primarily due to this aggregation. 

Heithaus, J. J., Measurement of Asphalt Viscosity with a Vacuum Capillary Viscometer, Papers on Road and Paving Materials and Symposium on Microviscomelry, ASTM STP 309, 1961, p. 63. 

Sisko, A. W., Determination and Treatment of Asphalt Viscosity Data Highway Research Board, Highway Research Record No. 67, 1965. 

The products could be classified as a function of various criteria physical properties (in particular, volatility), the way they are created (primary distillation or conversion). Nevertheless, the classification most relevant to this discussion is linked to the end product use LPG, premium gasoline, kerosene and diesel oil, medium and heavy fuels, specialty products like solvents, lubricants, and asphalts. Indeed, the product specifications are generally related to the end use. Traditionally, they have to do with specific properties octane number for premium gasoline, cetane number for diesel oil as well as overall physical properties such as density, distillation curves and viscosity. 

Analysis of certain papers requires special treatment before they can be disintegrated properly. Papers containing synthetics, tars, asphalt, mbber, viscose, or wet-strength resins must be analyzed individually (see TAPPI T401) (20). Dyes or colors must be removed from highly colored papers before examination. The method of dye removal depends on the type of dye. 

Asphalt Roofing Components. Asphalt (qv) is a unique building material which occurs both naturally and as a by-product of cmde-oil refining. Because the chemical composition of cmde oils differs from source to source, the physical properties of asphalts derived from various cmdes also differ. However, these properties can be tailored by further ptocessiag to fit the appHcation for which the asphalt will be used. Softening poiat, ductility, flash poiat, and viscosity—temperature relationship are only a few of the asphalt properties that ate important ia the fabricatioa of roofing products. 

Sulfur as an Additive for Asphalt. Sulfur-extended asphalt (SEA) binders are formulated by replacing some of the asphalt cement (AC) in conventional binders with sulfur. Binders that have sulfur asphalt weight ratios as high as 50 50 have been used, but most binders contain about 30 wt % sulfur. Greater latitude in design is possible for SEA paving materials, which are three-component systems, whereas conventional asphalt paving materials are two-component systems. Introduction of sulfur can provide some substantial benefits. At temperatures above 130°C, SEA binders have lower viscosities than conventional asphalt. The lower viscosity enables the plant to produce and compact the mix at lower temperatures than with conventional... 

Many existing roads fail because the asphalt becomes stiff and brittle. If the materials are too stiff, additives that lower the viscosity must be used. The feasibihty of usiag sulfur to soften or reduce the viscosity of the oxidized biader ia recycled pavements has been successfully demonstrated by the U.S. Bureau of Mines and others (55—57). 

Tar sand, also variously called oil sand (in Canada) or bituminous sand, is the term commonly used to describe a sandstone reservoir that is impregnated with a heavy, viscous black extra heavy cmde oil, referred to as bitumen (or, incorrectly, as native asphalt). Tar sand is a mixture of sand, water, and bitumen, but many of the tar sand deposits in the United States lack the water layer that is beHeved to cover the Athabasca sand in Alberta, Canada, thereby faciHtating the hot-water recovery process from the latter deposit. The heavy asphaltic organic material has a high viscosity under reservoir conditions and caimot be retrieved through a weU by conventional production techniques. 

Substituted Amide Waxes. The product of fatty acid amidation has unique waxlike properties (13). Probably the most widely produced material is N,1S7-distearylethylenediarnine [110-30-5] which has a melting point of ca 140°C, an acid number of ca 7, and a low melt viscosity. Because of its unusuaHy high melting point and unique functionaHty, it is used in additive quantities to raise the apparent melting point of themoplastic resins and asphalts, as an internal—external lubricant in the compounding of a variety of thermoplastic resins, and as a processing aid for elastomers. 

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. 

Type asphalt Diluent type Diluent, % Viscosity range, mm /s f= cSt)... 

The hquid cutback asphalts are prepared in a number of viscosity grades, ranging generally from 70 to 6000. The grade number indicates the viscosity at 60°C. 

Many investigators have also measured the trace metal content of asphalts (68). The catalytic behavior of vanadium has prompted studies of the relation between vanadium content and an asphalt s sensitivity to oxidation (viscosity ratio). The significance of metals in the behavior of asphalts is not yet well understood or defined. 

Fig. 12. A viscosity-temperature chart, mm /s = cSt ----, iadustrial asphalts ---cutback asphalts ...

Curves for the viscosity data, when displayed as a function of shear rate with temperature, show the same general shape with limiting viscosities at low shear rates and limiting slopes at high shear rates. These curves can be combined in a single master curve (for each asphalt) employing vertical and horizontal shift factors (77—79). Such data relate reduced viscosity (from the vertical shift) and reduced shear rate (from the horizontal shift). 

This equation is based on the approximation that the penetration is 800 at the softening point, but the approximation fails appreciably when a complex flow is present (80,81). However, the penetration index has been, and continues to be, used for the general characteristics of asphalt for example asphalts with a P/less than —2 are considered to be the pitch type, from —2 to +2, the sol type, and above +2, the gel or blown type (2). Other empirical relations that have been used to express the rheological-temperature relation are fluidity factor a Furol viscosity P, at 135°C and penetration P, at 25°C, relation of (H—P)P/100 and penetration viscosity number PVN again relating the penetration at 25°C and kinematic viscosity at 135 °C (82,83). 

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