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1、AS 1141.11.220081 AS 1141.11.22008Australian StandardMethods for sampling and testing aggregatesMethod 11.2: Particle size distribution for vision sizing systems1 SCOPEThis Standard sets out the method for the determination of particle size distribution in coarse and fine aggregates by vision system
2、s. The VSS is limited by the discrimination of the optical system and, at present, is suitable for materials coarser than 1.18 mm. A calibration procedure is required to relate results from this procedure to particle distribution by sieving (AS 1141.11).NOTE: A summary of VSS technology is given in
3、Appendix A.2 APPLICATIONAS 1141.11 measures particle size distribution of a sample on the basis of mass of sample passing or retained on the square or round hole sizes of the AS 1152 screens used. VSS measures the length dimensions of images of particles in two dimensions, and derives a third dimens
4、ion. VSS does not measure mass and, hence, variations in particle density in particles within a sample or between samples, will cause a difference in calculating the particle size distribution between the two methods. Some of this difference can be reduced by source calibration especially where the
5、VSS is used in an in-plant application on a consistent source. The VSS has application in the production of rapid, automated particle size distribution data in production plants.3 REFERENCED DOCUMENTSThe following documents are referred to in this Standard: AS1141Methods for sampling and testing agg
6、regates1141.1Method 1:Definitions1141.2Method 2:Basic testing equipment1141.3.1Method 3.1: SamplingAggregates1141.11Method 11: Particle size distribution by sieving1152Specification for test sieves4433Guide to the sampling of particulate materials4433.1Part 1:Sampling procedures Standards AustraliaA
7、S 1141.11.220084 DEFINITIONSFor the purposes of this Standard the definitions in AS 1141.1 and those below apply.4.1 Arithmetic mean size (AMS)The AMS is defined by VSS as follows: Standards Australiawww.standards.org.auwhereAMS =pd100p = individual percentage retained on each screend = mean size on
8、 each screen (screen above + this screen)/24.2 CalibrationThe procedure that converts VSS measurements to equivalent AS 1152 sieve sizes.4.3 Graded aggregateAn aggregate of which more than 15% of the total material is retained on at least three consecutive equivalent sieves in the set 75.0 mm, 37.5
9、mm, 26.5 mm, 19.0 mm, 13.2 mm,9.50 mm, 6.70 mm, 4.75 mm, and 2.36 mm. Crushed rock, which consists of a mixture offine and coarse aggregates, the coarse fraction being graded, is considered a graded aggregate for the purpose of this definition.4.4 Nominal sizeDesignation of an aggregate, which gives
10、 an indication of the largest size particle present.NOTE: The concept of nominal size aggregate is for convenience of reference and ordering. The nominal size is expressed as a whole number above the equivalent sieve size through which nearly all of the aggregate passes.4.5 One-sized aggregateAn agg
11、regate of which at least 60% of the total material passes an equivalent sieve, selected from the set 75.0 mm, 37.5 mm, 26.5 mm, 19.0 mm, 13.2 mm, 9.50 mm, 6.70 mm, 4.75 mm and 3.35 mm, which is immediately less than the nominal size of the aggregate and is retained on the equivalent sieve immediatel
12、y following the selected equivalent sieve in this series.4.6 Particle size distributionProportions by mass of the various particle size classes present.NOTE: VSS measures the size of particles as they are imaged in a measurement window. The measurements are corrected to equivalent AS 1141.11 sieve s
13、izes by a calibration routine using source reference samples.4.7 Primary reference sampleAn instrument integrity sample supplied by the manufacturer, which allows the instrument to be checked in the factory and at the users site. The primary reference sample is used to create a primary calibration.4
14、.8 Source Reference SampleA stable representative aggregate sample that has been accurately hand-sized for a defined size range using AS 1141.11, and used to create a source calibration, which is established on-site.4.9 Vision sizing system (VSS)A non-contact instrument that determines particle size
15、 in aggregates using an imaging process.5 APPARATUSThe following shall be required:(a) Sampling devicecomplying with AS 4433.1.NOTE: For a laboratory VSS, a sampling device is not required.(b)Hopperof sufficient volume to store the sample increment.(c) Vibrating-feederwhich operates at aconstant (pre-set)amplitude,andis independent of the load on the tray. The tray shall hav
