【国外标准】 Standard Specification for Graded Aggregate Material for Bases or Subbases for Highways or Airports

This specification covers quality-controlled graded aggregates that, when hauled to and properly spread and compacted on a prepared grade to appropriate density standards, may be expected to provide adequate stability and load support for use as highway or airport bases or subbases. Coarse aggregate retained on the sieve shall consist of durable particles of crushed stone, gravel, or slag capable of withstanding the effects of handling, spreading, and compacting without degradation productive of deleterious fines. Fine aggregate passing through the sieve shall normally consist of fines from the operation of crushing the coarse aggregate. Where available and suitable, addition of natural sand or finer mineral matter, or both, is not prohibited. The following tests shall be performed: grain-size test (dry and wet sieving), liquid limit test, plastic limit test, plasticity index test, sand equivalent value test, and expansion test.1.1 This specification covers quality-controlled graded aggregates that, when hauled to and properly spread and compacted on a prepared grade to appropriate density standards, may be expected to provide adequate stability and load support for use as highway or airport bases or subbases.NOTE 1: The engineer is cautioned to provide appropriate construction specifications to ensure compaction to an extent that further densification from traffic loadings on the completed pavement will be insignificant. The method suggested is to require compaction on a firm foundation of a short control strip of the material at a suitable moisture content, by means of vibratory or other proven effective rollers or tampers, until no further increase in density results. Compaction requirements should ensure that an average density of certain appropriate percentages of the control strip maximum density be achieved on the balance of the job; for base courses, 98 % is suggested as the minimum average requirement.1.2 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in nonconformance with the standard.1.3 The text of this standard references notes and footnotes which provide explanatory material. These notes and footnotes (excluding those in tables and figures) shall not be considered as requirements of the standard.1.4 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.1.5 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.