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1、BRITISH STANDARD BS 812-121: 1989 Testing aggregates Part 121: Method for determination of soundness UDC 625.07+691.22:620.168.2 BS 812-121:1989 This British Standard, having been prepared under the direction of the Cement, Gypsum, Aggregates and Quarry Products Standards Policy Committee, was publi
2、shed under the authority of the Board of BSI and comes 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 preparat
3、ion of 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
4、Consulting 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 Sci
5、ences British 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
6、Research 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 Institut
7、ion of 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
8、. No.Date of issueComments BS 812-121:1989 BSI 12-1998i Contents Page Committees responsibleInside front cover Forewordii 1Scope1 2Definitions1 3Principle1 4Sampling1 5Apparatus1 6Reagents1 7Preparation of test portions and specimens3 8Procedure3 9Calculation and expression of test results3 10Precis
9、ion4 11Test report4 Appendix A Recommended procedure for determining the magnesium sulphate soundness value for other size fractions of aggregate5 Appendix B Details of the evaluation of precision data5 Figure 1 Baskets for magnesium sulphate soundness testing2 Table 1 Recommended test sieves, mesh
10、baskets and mass of specimens for testing aggregates outside the size range 10.0 mm to 14.0 mm5 Table 2 Precision data for the magnesium sulphate soundness value = average MSSV at given statistical levels6 Publications referred toInside back cover x BS 812-121:1989 ii BSI 12-1998 Foreword This Part
11、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 BS 812. As each test, or collection of tests, is prepared it is intended to issue it as a separate Part or Sect
12、ion 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 BS 812 but have now been included because there is a need, in some circumstances, for a test to identify certain ag
13、gregates 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 BS 812-1101), BS 812-1111), BS 812-1121) and BS 812-1131), but which fail in service. The definitive method is based on findin
14、g the degree of degradation that occurs when test portions of an aggregate in the size range 10.0 mm to 14.0 mm 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 soundness value. App
15、endix 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 classifying the resistance
16、of building stone to deterioration under freeze-thaw conditions. In North America it has been incorporated in the ASTM book of standards, designation C88, since 1931. It did not come into widespread use in the United Kingdom until the late 1970s. Current experience of the use of the test in the UK r
17、elates 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 it is intended
18、that advice on calibration will be included in Part 1001). It is intended that other British Standards should call up BS 812 test methods as the basis for compliance. Nevertheless it is not intended that all aggregates should be subjected regularly to all the listed tests. Specifications in other st
19、andards should call up only relevant test methods. Reference should be made to BS 812-101 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 contract. Users
20、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 back cover and a ba
21、ck cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover. 1) In preparation. BS 812-121:1989 BSI 12-19981 1 Scope This Part of BS 812 describes the method for determining the soundn
22、ess 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 14.0 mm test sieve but is retained on a 10.0 mm test sieve. NOTE 1The majority of aggregates can be tested for s
23、oundness using this method. Precision has been established for the rock types listed in Table 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 magnesium bearing mi
24、nerals 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 BS 812 the definitions given in BS 8
25、12-101 and BS 812-102 apply. 3 Principle A sample of aggregate in the size range 10.0 mm to 14.0 mm is subjected to five cycles of: immersion in a saturated solution of magnesium sulphate; followed by oven-drying at 105 C to 110 C. This subjects the sample of aggregate to the disruptive effects of t
26、he 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 than 10.
27、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 clause 5 of BS 812-102:1984. 5 Apparatus 5.1 Test sieves, with square hole perforated plate of sizes 14.0 mm, 10.0 mm and 6.3 mm, and
28、a woven wire 3.35 mm test sieve. The test sieves shall comply with BS 410. 5.2 A balance, of at least 10 kg capacity, accurate to 5 g. 5.3 A balance, of at least 500 g capacity, accurate to 0.05 g. 5.4 At least two brass or stainless steel mesh baskets for immersing aggregate specimens in the soluti
29、on (see 6.3), which permit free access to the solution and drainage the solution from the aggregate under test. A suitable design is shown in Figure 1. 5.5 Containers, of diameter such that the baskets listed in 5.5 can be readily placed in and out, and with a volume at least five times the volume o
30、f the immersed aggregate (see note). NOTEPolypropylene beakers of 2 L capacity make suitable containers. 5.6 A means of maintaining the temperature of the solution, inside the containers, at 20 2 C (see note). NOTEA tank of the type used for curing concrete cubes has been found to be suitable. 5.7 A
31、n oven, capable of maintaining a temperature within the range 105 C to 110 C, with fan-assisted air circulation, and ventilation by convection. The oven shall be capable of being heated continuously at 105 C to 110 C, and the rate of evaporation at this range of temperature shall be at least 100 g o
32、ver 4 h, during which time the doors of the oven shall be kept closed. This rate shall be determined by the loss of water from 1 L squat beakers (Griffin low-form type), each initially containing 500 g of distilled water, at a temperature of 20 2 C, placed at each corner and at the centre of each sh
33、elf of the oven. The 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 a
34、lso been achieved with the oven loaded in a similar manner to that proposed. 5.8 A density hydrometer, complying with BS 718:1979 type M50, graduated at 20 C for medium surface tension 55 mN/m, to measure densities in the range 1.284 g/mL to 1.300 g/m L to an accuracy of 0.001 g/m L (see note). NOTE
35、A satisfactory method of using 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 in 5.4. 6 Reagents 6.1 A supply of distilled
36、 water or deionized water. 6.2 Barium chloride, 5 % solution. Dissolve 5 g of barium chloride in 100 mL of distilled or deionized water. 6.3 A saturated solution of magnesium sulphate. NOTEA minimum quantity of 3 L is required for each test. BS 812-121:1989 2 BSI 12-1998 6.3.1 For the preparation of
37、 this solution use crystalline magnesium sulphate heptahydrate (MgSO4.7H2O) 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 1 500 g of the crystalline salt to
38、each litre of water. During preparation maintain the temperature at between 25 C and 30 C and stir thoroughly during the addition of crystals. After preparation lower the temperature to 20 2 C maintain at this temperature for at least 48 h before use (see note). NOTEAccording to published data on th
39、e solubility of magnesium sulphate a saturated solution at 20 C contains a 25.2 % concentration of MgSO4(m/m)which has a relative density (20/4) of 1.290. The theoretical minimum mass of crystalline MgSO4.7H2O required to produce this degree of saturation, in 1 L of ion-free water at 20 C, is 1 092
40、g. The mass of 1 500 g is intended to 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 0.008 g/mL, using t
41、he density hydrometer, (see note to 5.8). 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 testing BS 812-121:1989 BSI 12-19983 7 Preparation of test portions and specimens 7.1 Reduce the laboratory sample by the pro
42、cedures described in clause 6 of BS 812-102:1984 to produce two test portions of sufficient mass such that each will produce a minimum mass of 500 g of the 10.0 mm to 14.0 mm size range when processed as described in 7.3. 7.2 Dry each test portion in the oven at 105 C to 110 C to constant mass and a
43、llow to cool in the desiccator to laboratory temperature. 7.3 Sieve each dried test portion using the 14.0 mm and 10.0 mm test sieves to obtain two test specimens of material, of 500 g approximate mass, in the size range 10.0 mm to 14.0 mm. 7.4 Wash the test specimens with distilled water until they
44、 are seen to be free from dust, allow to drain and dry in the oven at 105 C to 110 C for at least 24 h. Remove from the oven and allow to cool in the desiccator. 7.5 Repeat the sieving of each specimen using the 14.0 mm and 10.0 mm sieves to ensure that only material in this size range is used. 7.6
45、Weigh out between 420 g and 430 g of each test Specimen and record the masses (M1) to the nearest 0.1 g. 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.
46、7.7 Follow the procedure described in clause 8 for each specimen. 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 of 17 h 30 min. Suspend each baske
47、t so that there is a minimum of 20 mm of solution above the specimen and 20 mm 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
48、 solution and the test specimen to reduce evaporation and to prevent 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 of 2 h 15 min. Place the b
49、asket in the oven maintained at a temperature of 105 C to 110 C for at least 24 h. Remove the basket from the oven and leave to cool to laboratory temperature for 5 h 15 min. 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 30 min. 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. NO