【国外标准】 Standard Practice for Selection and Use of Emulsified Asphalts

4.1 As indicated by Specifications D977 and D2397/D2397M, emulsified asphalts are classified by type (rapid, medium, or slow setting) and by grade within type (viscosity in the case of the rapid-setting type or characteristic of the residual asphalt in the case of the medium and slow-setting types). Selection for use of a particular type and grade is controlled by type of construction (whether an application or a mix type), properties of the mineral aggregate (both grading and mineral composition), and environmental conditions during construction. For surface treatments and seals, emulsified asphalts are formulated to set rapidly upon contact with the mineral aggregate or pavement surface. When used in mix types, slower breaking is required to allow time for mixing and laydown. If the mix aggregate is open graded without appreciable fines, a medium-setting emulsified asphalt may be used that deposits a relatively hard asphalt. If the aggregate is dense-graded but does not contain a large amount of very fine material (dust), a medium-setting emulsified asphalt with a soft residue may be a good choice. However, if the dense-graded aggregate contains a large amount of very fine mineral matter, a slow-setting emulsified asphalt may be required.4.2 The recommendations in Table 1 should be considered only as a general guide for the selection of an emulsion for use. If the user is uncertain as to which to select for an intended use, the emulsified asphalt supplier should be contacted.(A) For definitions of terms used in this table, refer to Section 3 or Terminology D8.(B) RS-1 and CRS-1 may be used as a tack coat in special cases where night construction or high humidity exists.(C) Grades of emulsified asphalt other than MS-2h may be used where experience has shown that they give satisfactory performance.(D) May dilute with water by manufacturer or contractor per state regulation. Refer to specifying agency.1.1 This practice covers the selection of emulsified asphalts for various paving and allied uses.1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.1.4 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.