Soft asphalt

Soft asphalt (SA) is designed to be used for surface courses and can also be used for binder courses, regulating courses and bases on roads, airfields and other trafficked areas, especially in climates with low temperatures as in the Nordic countries. 

SA is an asphalt consisting of paving aggregates and soft bitumen as specified in EN 12591/AC (2009) (Table 2 or Table 3) (see also Section 3.4.1). 

SA is designed in accordance with CEN EN 13108-3 (2008), which employs empirical requirements. 

Because of their limited use, SAs are not going to be discussed in detail in this book. 

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Asphalt. This is a distillatioa residuum that can also be produced by propane deasphalting (Fig. 7) (33) and thereafter modified to meet specifications. For example, asphalt (qv) can be made softer by blending hard asphalt with the extract obtained ia the solveat treatmeat of lubricatiag oils. Oa the other hand, soft asphalts can be converted iato harder asphalts by oxidation (air blowiag). 

Penetration (ASTMD5). This is a commonly used consistency test. It involves the deterrnination of the extent to which a standard needle penetrates a propedy prepared sample of asphalt under definitely specified conditions of temperature, load, and time. The distance that the needle penetrates in units of mm/10 measured from 0 to 300, is the penetration value. Soft asphalts have high penetration values. 

Organic ply sheets are manufactured from 3 ft (91 cm) wide organic felts, saturated with soft asphalt, that cover 400 ft (37 m ). Laying lines are apphed to the top side of the ply sheets, and the felts are perforated about 2 to 4 in. (5 to 10 cm) on center to permit the gases to escape during the roof constmction process. 

CEN EN 13108-3 2006/AC. 2008. Bituminous mixtures - Material specifications - Part 3 Soft asphalt. Brussels CEN. 

PE/asphalt blends, particularly those prepared from soft asphalts. However, it is known that asphalt-polyethylene mixtures have a tendency toward gross phase separation, i.e., gross incompatibility, when standing at elevated temperature for long periods 19]. Therefore modification of PE is needed to enhance its compatibility with asphalt. 

Modification of PE by chlorination is a simple technique to change the polarity, to reduce the crystallinity, and to increase the elasticity of the polymer. Partially chlorinated polyolefin waxes were reported to improve stability of asphalt-polymer blends [20, 21], so we elected to prepare and characterize polyethylenes with various degrees of chlorination to improve the polymer Interaction with polar components of asphalt. The extent of chlorination can be used to vary the crystallinity of the polymer additive. The crystalline domains of polyolefins contribute to high temperature reinforcement while their amorphous domains, which exhibit very low glass transition temperatures, contribute additional toughness and ductility at low temperatures to PO/asphalt blends, particularly those prepared from soft asphalts. 

Float Test (ASTMD139). The consistency properties of an asphalt at a very low apphed force are indicated by this test. The test is normally used for those asphalts that are too soft for the penetration test. 

Type 11 asphalt is the second most common type of asphalt used because it offers the best compromise between softness and weatherabiHty and lack of fl °C with penetration at 25°C between 18 and 40 mm /10. It is for roof slopes less than 1 per 12 and is also called flat asphalt. If Type 11 asphalt is used on the roof, it cannot be used on flashings. 

Goal Tar. In roofing, coal tar is used as mopping bitumen in between 15 and 20% of the BUR roofs installed. Coal-tar pitch and asphalt are considered incompatible and should not be mixed. If mixed, an oily exudate is formed that plasticizes the bitumen, and the mixture remains soft and does not weather well. For this reason, if coal tar is used in BUR systems the felts must be coal-tar saturated. There has been some success using asphalt-coated fiber-glass mat felts with coal-tar pitch. However, this has only been done for a limited number of years so the actual compatibiHty is not fully known. 

Ballast mats, raw material of degrading regenerated rubber The raw material of regenerated rubber Products of molding and extrusion, rubber mats, soft pipes for irrigating, vases, modihed asphalt for paving Used in renewal of tire (under 20 p.m, 30 phr)... 

Amorphous solids resemble liquids in that their molecules are not organized in regular arrays. In fact, there is no clear distinction between amorphous solids and very viscous liquids. When asphalt gets hot, it becomes sticky and eventually melts, but whether sticky asphalt is a soft solid or a highly viscous liquid is a matter of perspective. 

Asphalt (referred to as bitumen in some parts of the world) is produced from the distillation residuum. In addition to road asphalt, a variety of asphalt grades for roofing and waterproofing are also produced. Asphalt has complex chemical and physical compositions, which usually vary with the source of the crude oil, and it is produced to certain standards of hardness or softness in controlled vacuum distillation processes (Barth, 1962 Bland and Davidson, 1967 Speight, 1999, and references cited therein Speight and Ozum, 2002). 

The float test is used to determine the consistency of asphalt at a specified temperature. One test method (ASTM D139) is normally used for asphalt that is too soft for the penetration test (ASTM D5, D217, D937, D1403 IP 50, 179, 310). 

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