Asphalt viscosity-temperature properties

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. 

Stock. Propane deasphalting also has the ability to reduce a residuum even further and to produce an asphalt product with lower viscosity, higher ductility, and higher temperature susceptibility than other asphalts, although such properties might be anticipated to be very much crude oil dependent. Propane deasphalting is conventionally applied to low-asphalt-content... 

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. 

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. 

Blends with styrenic block copolymers improve the flexibiUty of bitumens and asphalts. The block copolymer content of these blends is usually less than 20% even as Httie as 3% can make significant differences to the properties of asphalt (qv). The block copolymers make the products more flexible, especially at low temperatures, and increase their softening point. They generally decrease the penetration and reduce the tendency to flow at high service temperatures and they also increase the stiffness, tensile strength, ductility, and elastic recovery of the final products. Melt viscosities at processing temperatures remain relatively low so the materials are still easy to apply. As the polymer concentration is increased to about 5%, an interconnected polymer network is formed. At this point the nature of the mixture changes from an asphalt modified by a polymer to a polymer extended with an asphalt. 

Sulphlex binders share certain physicochemical properties in common. Their temperature-viscosity curves are similar to asphalt, and very unlike the behavior of elemental sulfur. 

The physical properties of several sulfur-asphalt blends were determined in the laboratory and are illustrated in Table I. The softening points and penetration of the asphalt were relatively unchanged. The viscosity of the sulfur-asphalt blend is generally lower at all temperatures and is significantly less at 135 °C. The aggregates used in the trial are described in Table II. 

The allowable sulfur concentration in the binder depends on the properties of the asphalt. For example, asphalts A and B (Appendix, Table A-I) exhibit significantly different viscosities at the Marshall test temperature of 60°C. This difference is reflected by differences in mix stability at similar asphalt contents, shown in the Appendix and in Figure 6, i.e., 11120 N and 5960 N for asphalt A and B, respectively, at a content of 6 wt %. Asphalt B yields high-stability mixes and is not as prone to softening by low sulfur concentrations in the binder, whereas asphalt A exhibits the reverse behavior. 

Natural and synthetic rubbers have been studied as additives to alter the viscosity, ductility, and flow properties of road building asphalts. Welbom and Babashak (23) added natural rubber and sulfur to asphalt and reported improved blending conditions, improved stability, increased toughness, and low temperature ductility. 

Immobile is a solid or liquid organic matter with kinematic viscosity greater than 1,000 cm c E This is first of all dispersed organic matter of rocks, humus of soil, peat, etc., or very viscous or solid bitumens and petroleum products. Bitumens in conditions of high temperature are capable of slowly migrating. In particular, bitumens emerge on the surface in the Dead Sea, for which it was called Asphalt Sea. Nevertheless, these organic solvents is convenient to consider a component of rocks or deposits, and their absorption capability to consider as property of rock as a whole. 

There have been a number of not particularly successful attempts to correlate asphalt physical properties to chemical properties, including SEC (10,19,35-40). Chollar et al. (41) attempted to relate a number of chemical and physical properties, including percentage LMS, with poor results. Huynh et al. (42) divided asphalt into a number of fractions by preparatory SEC and showed that the glass transition temperature (not precisely defined for asphalts), in moving from one fraction to the next, first decreased with increasing molecular size and then increased. Beazly et al. (43) used SEC and nuclear magnetic resonance (NMR) to estimate asphalt yields and viscosity from crude oil Woods et al. (44) used SEC fractions to study differences in maltenes from tar sand bitumens. 

This test method covers the determination of the viscosity of asphalt cements by means of a cone-plate viscometer. It is applicable to materials having viscosities in the range from 10 to 10 P (10 to 10 Pa s) and is therefore suitable for use at temperatures where viscosity is in the range indicated. The shear rate may vary between approximately 10 to 10 s and the method is suitable for determination on materials having either Newtonian or non-Newtonian flow properties. 

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