BS 812-121-1989 Testing aggregates Method for determination of soundness《集料试验 坚固性的测定方法》.pdf

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1、BRITISH STANDARD BS 812-121: 1989 Testing aggregates Part 121: Method for determination of soundness UDC 625.07+691.22:620.168.2BS812-121:1989 This British Standard, having been prepared under the direction of the Cement, Gypsum,Aggregates and QuarryProducts Standards PolicyCommittee, was published

2、under the authority of the Board of BSIandcomes into effect on 31 October 1989 BSI 12-1998 The following BSI references relate to the work on this standard: Committee reference CAB/2 Draft for comment 88/10129 DC ISBN 0 580 17765 3 Committees responsible for this British Standard The preparation of

3、this British Standard was entrusted by the Cement, Gypsum, Aggregates and Quarry Products Standards Policy Committee (CAB/-) to Technical Committee CAB/2, upon which the following bodies were represented: Aggregate Concrete Block Association Association of Consulting Engineers Association of Consult

4、ing Scientists Association of Lightweight Aggregate Manufacturers Brick Development Association British Aggregate Construction Materials Industries British Cement Association British Ceramic Research Ltd British Civil Engineering Test Equipment Manufacturers Association British Geological Sciences B

5、ritish Precast Concrete Federation Ltd British Ready Mixed Concrete Association British Steel Industry Building Employers Confederation Calcium Silicate Brick Association Limited Chartered Institute of Building Concrete Society County Surveyors Society Department of the Environment (Building Researc

6、h Establishment) Department of Environment (Property Services Agency) Department of Transport Department of Transport (Transport and Road Research Laboratory) Electricity Supply Industry in England and Wales Federation of Civil Engineering Contractors Institute of Concrete Technology Institution of

7、Civil Engineers Institution of Highways and Transportation Institution of Structural Engineers Institution of Water and Environmental Management (IWEM) Mortar Producers Association Limited Sand and Gravel Association Limited Society of Chemical Industry Amendments issued since publication Amd. No. D

8、ate of issue CommentsBS 812-121:1989 BSI 12-1998 i Contents Page Committees responsible Inside front cover Foreword ii 1 Scope 1 2 Definitions 1 3 Principle 1 4 Sampling 1 5 Apparatus 1 6 Reagents 1 7 Preparation of test portions and specimens 3 8 Procedure 3 9 Calculation and expression of test res

9、ults 3 10 Precision 4 11 Test report 4 Appendix A Recommended procedure for determining themagnesium sulphatesoundness value for other size fractions of aggregate 5 Appendix B Details of the evaluation of precision data 5 Figure 1 Baskets for magnesium sulphate soundness testing 2 Table 1 Recommende

10、d test sieves, mesh baskets and mass of specimens for testing aggregates outside the size range 10.0mm to 14.0mm 5 Table 2 Precision data for the magnesium sulphate soundness value = average MSSV at given statistical levels 6 Publications referred to Inside back cover xBS812-121:1989 ii BSI 12-1998

11、Foreword This Part of BS 812 has been prepared under the direction of the Cement, Gypsum, Aggregates and Quarry Products Standards Policy Committee. It forms part of a general revision of the 1975 edition of BS812. As each test, or collection of tests, is prepared it is intended to issue it as a sep

12、arate Part or Section of this standard. This Part of BS 812 contains the test procedures for the determination of the “soundness” of aggregates. Soundness tests were not included in previous editions of BS812 but have now been included because there is a need, in some circumstances, for a test to id

13、entify certain aggregates which are apparently suitable for use, when tested by the test procedures described in other Parts of this standard (e.g. the mechanical strength tests described in BS812-110 1) , BS812-111 1) , BS812-112 1)and BS812-113 1) , but which fail in service. The definitive method

14、 is based on finding the degree of degradation that occurs when test portions of an aggregate in the size range 10.0mm to 14.0mm are subjected to cycles of immersion in saturated magnesium sulphate solution followed by oven-drying. The degree of degradation is expressed as the magnesium sulphate sou

15、ndness value. Appendix A recommends procedures for carrying out the test on test portions of aggregate in size ranges other than the one used in the definitive method. The sulphate soundness test has a long history. It is reported that it first appeared in France around 1818 as a test for classifyin

16、g the resistance of building stone to deterioration under freeze-thaw conditions. In North America it has been incorporated in the ASTM book of standards, designation C88, since1931. It did not come into widespread use in the United Kingdom until the late 1970s. Current experience of the use of the

17、test in the UK relates mainly to aggregates in materials forming the surfacing of airfields/airports and of highway pavements. It is intended that advice on the applicability of this test for given situations and on the selection of limits will be included in future Parts of this standard. Similarly

18、 it is intended that advice on calibration will be included in Part 100 1) . It is intended that other British Standards should call up BS812 test methods as the basis for compliance. Nevertheless it is not intended that all aggregates should be subjected regularly to all the listed tests. Specifica

19、tions in other standards should call up only relevant test methods. Reference should be made to BS812-101 for general guidance on testing aggregates, precision of test methods and variance arising from sampling errors. A British Standard does not purport to include all the necessary provisions of a

20、contract. Users of British Standards are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pages i and ii, pages 1 to 6, an inside bac

21、k cover and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on theinside front cover. 1) In preparation.BS 812-121:1989 BSI 12-1998 1 1 Scope This Part of BS 812 describes the method for determi

22、ning the soundness of aggregates by subjecting the aggregate to cycles of immersion in a saturated solution of magnesium sulphate followed by oven-drying. The method is applicable to aggregate passing a 14.0mm test sieve but is retained on a 10.0mm test sieve. NOTE 1The majority of aggregates can be

23、 tested for soundness using this method. Precision has been established for the rock types listed inTable 1. The test may not be suitable for all rock types and reservations have been expressed elsewhere in respect of some carbonate aggregates and some aggregates having a high proportion of magnesiu

24、m bearing minerals or of cryptocrystalline quartz. For other size fractions, a recommended method is described in appendix A. NOTE 2The titles of the publications referred to in this standard are listed on the inside back cover. 2 Definitions For the purposes of this Part of BS812 the definitions gi

25、ven in BS 812-101 and BS 812-102 apply. 3 Principle A sample of aggregate in the size range 10.0mm to14.0mm is subjected to five cycles of: immersion in a saturated solution of magnesium sulphate; followed by oven-drying at 105C to 110C. This subjects the sample of aggregate to the disruptive effect

26、s of the repeated crystallization and rehydration of magnesium sulphate within the pores of the aggregate. The extent of the disruption is dependent upon the soundness of the aggregate. The degree of degradation arising from the disruptive effects is measured by the extent to which material finer th

27、an 10.0 mm in particle size is produced. 4 Sampling The sample to be used for the test (the laboratory sample) shall be taken in accordance with the procedure described in clause5 of BS 812-102:1984. 5 Apparatus 5.1 Test sieves, with square hole perforated plate of sizes 14.0mm, 10.0mm and 6.3mm, an

28、d a woven wire 3.35mm test sieve. The test sieves shall comply with BS410. 5.2 A balance, of at least 10kg capacity, accurate to5g. 5.3 A balance, of at least 500g capacity, accurate to0.05g. 5.4 At least two brass or stainless steel mesh baskets for immersing aggregate specimens in the solution (se

29、e6.3), which permit free access to the solution and drainage the solution from the aggregate under test. A suitable design is shown inFigure 1. 5.5 Containers, of diameter such that the baskets listed in5.5 can be readily placed in and out, and with a volume at least five times the volume of the imm

30、ersed aggregate (see note). NOTEPolypropylene beakers of 2L capacity make suitable containers. 5.6 A means of maintaining the temperature of the solution, inside the containers, at 20 2 C (seenote). NOTEA tank of the type used for curing concrete cubes has been found to be suitable. 5.7 An oven, cap

31、able of maintaining a temperature within the range 105C to 110C, with fan-assisted air circulation, and ventilation by convection. The oven shall be capable of being heated continuously at 105C to 110C, and the rate of evaporation at this range of temperature shall be at least 100g over 4h, during w

32、hich time the doors of the oven shall be kept closed. This rate shall be determined by the loss of water from 1L squat beakers (Griffin low-form type), each initially containing 500g of distilled water, at a temperature of 20 2 C, placed at each corner and at the centre of each shelf of the oven. Th

33、e evaporation requirement is to apply to each test location with the oven empty except for beakers of water (see note). NOTEThe oven should not be used for any other purposes while in use for the test unless it has been shown previously that the above performance requirement has also been achieved w

34、ith the oven loaded in a similar manner to that proposed. 5.8 A density hydrometer, complying with BS718:1979 type M50, graduated at 20C for medium surface tension 55mN/m, to measure densities in the range1.284g/mL to 1.300g/mL to an accuracy of 0.001g/mL (see note). NOTEA satisfactory method of usi

35、ng the hydrometer is to decant the solution under test into a gas jar, measure the density, and then to return the solution to its original container. 5.9 A desiccator, large enough to contain at least two of the baskets listed in5.4. 6 Reagents 6.1 A supply of distilled water or deionized water. 6.

36、2 Barium chloride, 5% solution. Dissolve 5g of barium chloride in 100mL of distilled or deionized water. 6.3 A saturated solution of magnesium sulphate. NOTEA minimum quantity of 3 L is required for each test.BS812-121:1989 2 BSI 12-1998 6.3.1 For the preparation of this solution use crystalline mag

37、nesium sulphate heptahydrate (MgSO 4 .7H 2 O) general purpose reagent (GPR) grade (see note). NOTEMagnesium sulphate B.P. (Epsom salts), obtainable from pharmaceutical chemists, is suitable. 6.3.2 Prepare the solution by slowly adding 1500g of the crystalline salt to each litre of water. During prep

38、aration maintain the temperature at between25C and 30C and stir thoroughly during the addition of crystals. After preparation lower the temperature to 20 2 C maintain at this temperature for at least 48h before use (see note). NOTEAccording to published data on the solubility of magnesium sulphate a

39、 saturated solution at 20C contains a25.2% concentration of MgSO 4 (m/m)which has a relative density (20/4) of 1.290. The theoretical minimum mass of crystalline MgSO 4 .7H 2 O required to produce this degree of saturation, in 1L of ion-free water at 20C, is 1092 g. The mass of 1500g is intended to

40、ensure that excess crystals are present in the solution during preparation and all subsequent stages of the tests, but further quantities should be added if necessary. 6.3.3 Prior to use check that the solution has achieved a density of 1.292 0.008g/mL, using the density hydrometer, (see note to5.8)

41、. If not, reject the solution and repeat stages 6.3.2 and 6.3.3 using fresh crystals. Figure 1 Basket for magnesium sulphate soundness testingBS 812-121:1989 BSI 12-1998 3 7 Preparation of test portions and specimens 7.1 Reduce the laboratory sample by the procedures described in clause 6 of BS 812-

42、102:1984 to produce two test portions of sufficient mass such that each will produce a minimum mass of 500g of the10.0mm to 14.0mm size range when processed as described in7.3. 7.2 Dry each test portion in the oven at 105C to110C to constant mass and allow to cool in the desiccator to laboratory tem

43、perature. 7.3 Sieve each dried test portion using the 14.0mm and 10.0mm test sieves to obtain two test specimens of material, of 500g approximate mass, in the size range 10.0mm to 14.0mm. 7.4 Wash the test specimens with distilled water until they are seen to be free from dust, allow to drain and dr

44、y in the oven at 105C to 110C for at least 24h. Remove from the oven and allow to cool in the desiccator. 7.5 Repeat the sieving of each specimen using the14.0mm and 10.0mm sieves to ensure that only material in this size range is used. 7.6 Weigh out between 420g and 430g of each test Specimen and r

45、ecord the masses (M 1 ) to the nearest0.1g. Transfer the specimens to two labelled mesh baskets. NOTEIn order to reduce to a minimum any loss by abrasion, take care to avoid shaking the specimens in their baskets at all subsequent stages. 7.7 Follow the procedure described in clause8 for each specim

46、en. 8 Procedure 8.1 Immerse the basket, containing the specimen under test, in a container holding the saturated solution of magnesium sulphate, so that the aggregate is completely immersed, for a period of17h 30min. Suspend each basket so that there is a minimum of 20mm of solution above the specim

47、en and 20mm separation from any salt cake accumulation or from any other basket. Take particular care during the process of immersion to ensure that no whole piece of aggregate is lost from the basket. Cover the container holding the solution and the test specimen to reduce evaporation and to preven

48、t ingress of foreign matter. NOTEClock glasses are suitable covers. 8.2 At the end of the immersion period remove the basket from the solution, cover the container and leave the basket to drain for a period of2h 15min. Place the basket in the oven maintained at a temperature of 105C to 110C for at l

49、east 24h. Remove the basket from the oven andleave to cool to laboratory temperature for5h 15min. 8.3 Prior to the next immersion break up any salt cake which may have accumulated at the bottom of the container, stir the solution thoroughly with a glass rod and allow to settle for 30min. Check that the density of the solution in the container is still in the required range and if it is not replace it with unused saturated solution of magnesium sulphate. NOTEIn cases where severe disintegration of the aggregate occurs during the course of