BS 812-124-2009 Testing aggregates nPart 124 Method for determination nof frost heave《集料试验 第124部分 冻胀的测定方法》.pdf

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1、Testing aggregatesPart 124: Method for determination of frost heaveBS 812-124:2009raising standards worldwideNO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWBSI British StandardsBS 812-124:2009 BRITISH STANDARDPublishing and copyright informationThe BSI copyright notice display

2、ed in this document indicates when the document was last issued. BSI 2009 ISBN 978 0 580 62926 6ICS 91.100.15The following BSI references relate to the work on this standard: Committee reference B/502 Draft for comment 08/30181505 DCPublication historyFirst published August 1989Second (present) edit

3、ion, April 2009Amendments issued since publicationDate Text affected BRITISH STANDARD BSI 2009 iBS 812-124:2009ContentsForeword ii1 Scope 12 Normative references 13 Terms and definitions 14 Principle 25 Sampling and sample reduction 26 Apparatus 37 Preliminary testing procedure 98 Preparation of tes

4、t specimens 109 Procedure for the determination of frost heave 1310 Calculation and expression of results 1811 Test report 1912 Precision 20AnnexesAnnex A (normative) Self-refrigeration unit 21Annex B (normative) Use of comparator specimens 29List of figuresFigure 1 Mould and end plugs for the prepa

5、ration of frost-heave test specimens 4Figure 2 Hand-held tamper 5Figure 3 100 mm tamping foot for vibrating hammer 6Figure 4 Specimen extruder 7Figure 5 Extrusion cylinder 8Figure 6 Extrusion process 9Figure 7 Specimen cradle showing specimen position numbers 14Figure 8 Principle of a constant level

6、 device to control water supply to frost resistance specimens 16Figure A.1 Main features and dimensions of test chamber 22Figure A.2 Specimen carriers 24Figure B.1 SRU tuning, temperature recording chart 31Figure B.2 SRU tuning, temperature parameter summary chart 32List of tablesTable 1 Minimum mas

7、s of test portion 2Table 2 Precision estimates, frost resistance 20Summary of pagesThis document comprises a front cover, an inside front cover, pages i to ii, pages 1 to 32, an inside back cover and a back cover.BS 812-124:2009ii BSI 2009BRITISH STANDARDForewordPublishing informationThis part of BS

8、 812 is published by BSI and came into effect on 30 April 2009. It was prepared by Subcommittee B/502/6, Test methods, under the authority of Technical Committee B/502, Aggregates. A list of organizations represented on this committee can be obtained on request to its secretary.SupersessionThis part

9、 of BS 812 supersedes BS 812-124:1989, which is withdrawn.Presentational conventionsThe provisions of this standard are presented in roman (i.e. upright) type. Its methods are expressed as a set of instructions, a description, or in sentences in which the principal auxiliary verb is “shall”.Commenta

10、ry, explanation and general informative material is presented in smaller italic type, and does not constitute a normative element.Contractual and legal considerationsThis publication does not purport to include all the necessary provisions of a contract. Users are responsible for its correct applica

11、tion.Compliance with a British Standard cannot confer immunity from legal obligations.BRITISH STANDARD BSI 2009 1BS 812-124:20091 ScopeThis British Standard describes a test procedure for the determination of the frost resistance of unbound aggregate mixtures that have been compacted to form a cylin

12、drical specimen with a predetermined water content and density. It is applicable to unbound aggregate mixtures used in the construction of roads and other paved areas at a depth that might experience frost penetration.NOTE This method can be used to assess hydraulically bound aggregate mixtures. How

13、ever, acceptable values of frost heave might differ from those used to assess unbound mixtures.This British Standard includes an option for the use of comparator specimens to confirm that the test chamber is working correctly. The method for the use of comparator specimens is given in Annex B.2 Norm

14、ative referencesThe following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.BS EN 932-1, Tests for general pro

15、perties of aggregates Part 1: Methods for samplingBS EN 932-2, Tests for general properties of aggregates Part 2: Methods for reducing laboratory samplesBS EN 932-5, Tests for general properties of aggregates Part 5: Measurement and calibration systemsBS EN 933-1, Tests for geometrical properties of

16、 aggregates Part 1: Determination of particle size distribution Sieving methodBS EN 933-2, Tests for geometrical properties of aggregates Part 2: Determination of particle size distribution Test sieves, nominal size of aperturesBS EN 1097-5, Tests for mechanical and physical properties of aggregates

17、 Part 5: Determination of the water content by drying in a ventilated ovenBS EN 13286-4, Unbound and hydraulically bound mixtures Test methods for laboratory dry density and water content Part 4: Vibrating hammerBS EN 60584-2, Thermocouples Part 2: Tolerances3 Terms and definitionsFor the purposes o

18、f this British Standard, the following terms and definitions apply.3.1 constant massmass achieved by successive weighings after drying at least 1 hour apart not differing by more than 0.1%NOTE In many cases constant mass can be achieved after a test portion has been dried for a predetermined period

19、in a specified oven (see 6.3.13) at (110 null 5) C. Test laboratories may determine the time required to achieve constant mass for specific types and sizes of sample, dependent upon the drying capacity of the oven used.BS 812-124:20092 BSI 2009BRITISH STANDARD3.2 frost heavemaximum increase in the h

20、eight of a test specimen during the freezing period3.3 laboratory samplereduced sample derived from a bulk sample for laboratory testing3.4 test specimensample used in a single determination when a test method requires more than one determination of a property4 PrincipleCylindrical specimens of unbo

21、und aggregate mixtures, compacted at a predetermined water content and density, are placed in a self-refrigerated unit (SRU). The SRU subjects the upper surface of each test specimen to freezing air at 17 C whilst their lower ends have access to water maintained at +4 C. Comparator specimens can be

22、used to confirm that the SRU is operating correctly.The temperature gradient in the SRU causes water to be drawn into the freezing zone and might lead to the formation of ice lenses that increase the height of the specimens. The change in height is measured at intervals over a period of 96 h. The ma

23、ximum increase is recorded and is used to calculate the frost heave of the mixture.5 Sampling and sample reductionTake the laboratory sample of unbound aggregate mixture to be sent to the laboratory in accordance with BS EN 932-1.The mass of the laboratory sample shall be at least twice the quantity

24、 estimated as being necessary for the tests to be carried out. The minimum amount required for each test shall conform to Table 1. When required, divide and reduce the size of the laboratory sample in accordance with BS EN 932-2.NOTE The values in Table 1 are calculated using a loose bulk density of

25、 2.0 Mg/m3.Table 1 Minimum mass of test portionTest method Minimum mass of test portion kg BS EN 933-1 Particle size distribution (0/32 mm size mixture)10BS EN 13286-4 Dry density and water content by vibrating hammer40BS 812-124 Determination of frost heave 36BRITISH STANDARD BSI 2009 3BS 812-124:2

26、0096 Apparatus6.1 Particle size apparatusThe apparatus for the determination of the particle size distribution shall be as specified in BS EN 933-1.6.2 Dry density and water content relation apparatusThe apparatus for determining the relationship between the dry density and water content of the unbo

27、und aggregate mixture shall be as specified in BS EN 13286-4.6.3 Frost test apparatus6.3.1 The apparatus for determining the frost resistance of the material shall be as specified in 6.3.2 to 6.3.15. Unless otherwise stated, all apparatus shall conform to BS EN 932-5.6.3.2 Selfrefrigerated unit (SRU

28、), as described in Annex A.6.3.3 Balance(s), of suitable capacity, readable to 0.1% of the mass of the test portion.6.3.4 Container, of suitable capacity, for the controlled addition of water to the test specimens.6.3.5 Mixing bowl and suitable spatula or trowel. NOTE Alternative methods of mixing m

29、ay be used providing they are effective in distributing the added water evenly through the specimen.6.3.6 Containers, at least nine, that can each hold 15 kg of mixture and are closeable.6.3.7 Low carbon steel mould and end plugs, for specimen preparation, as shown in Figure 1.6.3.8 Handheld steel t

30、amper, weighing 1 100 g to 1 200 g.NOTE A suitable design is shown in Figure 2.6.3.9 Electrically powered vibrating hammer, as described in BS EN 13286-4.6.3.10 Steel tamper, with a circular foot of 100 mm diameter, to fit the vibrating hammer. NOTE A suitable design is shown in Figure 3. The shank

31、is a forcefit into the disc.6.3.11 Depth gauge, capable of reading depths up to 250 mm and readable to 1 mm.6.3.12 Jacking device, for ejecting the compacted specimen from the mould.NOTE 1 A compression testing machine with suitable extension extruders has been found suitable.NOTE 2 The apparatus us

32、ed at the extrusion stage is illustrated in Figure 4, Figure 5 and Figure 6.6.3.13 Ventilated oven, thermostatically controlled to maintain a temperature of (110 null 5) C.6.3.14 Test sieve, 40 mm size, as specified in BS EN 933-2.6.3.15 A supply of distilled or demineralized water. BS 812-124:20094

33、 BSI 2009BRITISH STANDARDFigure 1 Mould and end plugs for the preparation of frost-heave test specimensMaterial: Low carbon steel. Dimensions in millimetres.12711896102.08102.16124563100.8100.9121413X XX-X7102.24102.32101.00101.05119.5120.58910112589330Key1 Medium diamond knurl2 Undercut 95 (typical

34、)3 Undercut: 3.0 4 All welds 5 mm continuous fillet5 End plug (large)6 Undercut: 6.0 7 Webs: 138 Mould9 Straight polished taper10 Length of taper: 152.4 11 Identification groove 12 wide 0.3 deep to denote smaller bore and paint12 End plug (small)13 Other dimensions as end plug (large)14 Paint surfac

35、e for identificationBRITISH STANDARD BSI 2009 5BS 812-124:2009Figure 2 Hand-held tamperMaterial: Low carbon steel. Dimensions in millimetres.161233510A-AA A99.5100.5Key1 Chamfer 1.5 452 Thread M10 and machine flush with end face on assembly; finally, secure with an industrial adhesive BS 812-124:200

36、96 BSI 2009BRITISH STANDARDFigure 3 100 mm tamping foot for vibrating hammerMaterial: Low carbon steel. Dimensions in millimetres.199.5100.54012Key1 Shank design to suit vibrating hammerMass of tamper not to exceed 3 kg.NOTE This design has been found satisfactory, but alternative design may be empl

37、oyed provided that the essential requirements are fulfilled.BRITISH STANDARD BSI 2009 7BS 812-124:2009Figure 4 Specimen extruderMaterial: Low carbon steel. Dimensions in millimetres.100.8100.993X X2AA 213341546Key1 Undercut: 32 Undercut 95 (typical)3 Dimension A:Long extruder: 330Short extruder: 174

38、4 Webs: 135 All welds 5 mm continuous fillet6 Medium diamond knurl 127BS 812-124:20098 BSI 2009BRITISH STANDARDFigure 5 Extrusion cylinderDimensions in millimetres.1123105.0106.0121.25121.5012775505060240Key1 Medium diamond knurlBRITISH STANDARD BSI 2009 9BS 812-124:2009Figure 6 Extrusion process Di

39、mensions in millimetres.12345774533Key1 Extrusion cylinder2 Specimen3 Mould (see Figure 1) 4 Extruded specimen5 Long extruder (see Figure 4)7 Preliminary testing procedure7.1 Particle-size distributionDetermine the particle-size distribution of a test portion taken from the laboratory sample in acco

40、rdance with BS EN 933-1.NOTE 1 Before proceeding with further testing, the determined particle size distribution should be checked to confirm that it is typical of the routine production from the source. For some unbound mixtures, this might involve comparison with the supplier declared value for gr

41、ading. If there is a discrepancy, a more representative sample should be obtained before continuing.NOTE 2 Typical particle size distribution results are normally available from the supplier of the unbound mixture.BS 812-124:200910 BSI 2009BRITISH STANDARD7.2 Water content and dry density7.2.1 Stage

42、 1If values are not nominated from previous tests (see Note 1), determine the optimum water content and maximum dry density of test specimens taken from the laboratory sample in accordance with BS EN 13286-4 (see Note 2). Use these values for the initial preparation of a frost heave test specimen, a

43、s described in 7.2.2.NOTE 1 The water content and density at which test specimens are to be prepared may be nominated before testing, on the basis of earlier tests.NOTE 2 The primary requirement when choosing suitable values of water content and dry density is that the test specimens should be stabl

44、e. 7.2.2 Stage 2Prepare a test specimen from the laboratory sample with a mass of not less than 5 kg. Dry the test specimen by heating at a temperature of (110 null 5) C to constant mass. Allow it to cool, pass through the 40 mm size test sieve (6.3.14) and remove any particles retained on the sieve

45、.Use the dried and sieved test specimen to prepare a frost heave test specimen using the water content (w, expressed as a percentage by weight) and dry density (dMg/m3) chosen in Stage 1 (see 7.2.1). Use a mass of dry aggregate equal to 1 360 d(in grams) and a mass of water equal to 13.6 wd(in grams

46、).Place the dried aggregate in the mixing bowl (6.3.5), add the water and thoroughly mix.Use this mixture to prepare and extrude a trial frost heave test specimen, using the procedures in 8.4.If, immediately after extrusion, the specimen cannot stand on the extruder without collapsing, adjust the dr

47、y density and/or water content values to achieve a specimen that is sufficiently stable but has not been subjected to such a degree of compaction that undue crushing of the individual particles has occurred. NOTE 1 Adjustment should be achieved systematically by trial and error, until a stable speci

48、men has been made.NOTE 2 The values of water content and dry density used to prepare the stable specimen are used to prepare the test specimens in Clause 8.When a stable specimen has been prepared, transfer the test specimen to a suitable tray and break it up. Determine the moisture content of the t

49、est specimen in accordance with BS EN 1097-5 and the particle size distribution of the test specimen in accordance with BS EN 933-1.8 Preparation of test specimens8.1 GeneralThe test procedure described in Clause 9 uses three frost heave test specimens for each test on an unbound aggregate mixture.NOTE The SRU can accommodate nine specimens. This means that three different unbound mixtures can be tested at one time. If three comparator specimens (Annex B) are used, two u