【国外标准】 Standard Test Method for Determining Field VMA Based on the Maximum Specific Gravity of an Asphalt Mixture (Gmm)

4.1 Various users desire indication of compliance with VMA specifications for hot mix asphalt (HMA) during production.4.2 The standard practice for determining VMA requires that the bulk specific gravity of the aggregate components be determined. This is a very time-consuming test, which is not suitable for routine QC procedures.4.3 When an aggregate source used in the mix has a highly variable bulk specific gravity and a reference average bulk specific gravity (Gsb) (for example, as established in the mix design) is used to calculate VMA during HMA production, erroneous values may occur.4.4 The test for maximum specific gravity of the mix (Gmm) is a routine QC test at HMA plants. The effective specific gravity of the aggregate components (Gse) can be easily calculated from this test. However the Gse does not take into account the amount of asphalt absorbed, which is required for accurate VMA determination. This method provides a means to correct the Gse to account for the average absorbed asphalt. This procedure should not be used if the percent water absorption of the total (combined) aggregates varies between four tests, randomly obtained over a 30 day period, by more than 0.4 %.1.1 This test method is intended to be used for a rapid field determination of voids in mineral aggregate (VMA) of asphalt mixture. It provides equations for calculating the VMA based on the asphalt content of the mix and its maximum specific gravity (Gmm). It is intended that this should be used for the rapid “field” determination of VMA during quality control (QC) operations at HMA plants, particularly where the specific gravity of the aggregate is highly variable.NOTE 1: VMA determined using the rapid field method is VMA that has been corrected for aggregate absorption.1.2 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.1.3 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.