SANS 5850-2-2008 Sulfates content of fines in aggregates Part 2 Acid-soluble sulfates in fines in aggregates《骨料中粉状硫酸盐含量 第2部分 骨料中粉状酸溶性硫酸盐含量》.pdf

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1、 Collection of SANS standards in electronic format (PDF) 1. Copyright This standard is available to staff members of companies that have subscribed to the complete collection of SANS standards in accordance with a formal copyright agreement. This document may reside on a CENTRAL FILE SERVER or INTRA

2、NET SYSTEM only. Unless specific permission has been granted, this document MAY NOT be sent or given to staff members from other companies or organizations. Doing so would constitute a VIOLATION of SABS copyright rules. 2. Indemnity The South African Bureau of Standards accepts no liability for any

3、damage whatsoever than may result from the use of this material or the information contain therein, irrespective of the cause and quantum thereof. ISBN 978-0-626-21583-5 SANS 5850-2:2008Edition 1.3Any reference to SABS SM 850-2 is deemedto be a reference to this standard(Government Notice No. 1373 o

4、f 8 November 2002)SOUTH AFRICAN NATIONAL STANDARD Sulfates content of fines in aggregates Amdt 1 Part 2: Acid-soluble sulfates in fines in aggregates Published by SABS Standards Division 1 Dr Lategan Road Groenkloof Private Bag X191 Pretoria 0001 Tel: +27 12 428 7911 fax: +27 12 344 1568 www.sabs.co

5、.za SABS SANS 5850-2:2008 Edition 1.3 Table of changes Change No. Date Scope Amdt 1 1998 Amended to change the number, the title of this standard and to change the reference of first revision to the first edition. Amdt 2 2002 Amended to update normative references. Amdt 3 2008 Amended to change the

6、designation of SABS standards to SANS standards, and to update referenced standards. Foreword This South African standard was approved by National Committee SABS SC 59A, Construction standards Cement, lime and concrete, in accordance with procedures of the SABS Standards Division, in compliance with

7、 annex 3 of the WTO/TBT agreement. This document was published in August 2008. This document supersedes SABS SM 850-2:2002 (edition 1.2). A vertical line in margin shows where the text has been technically modified by amendment No. 3. SANS 5850-2:2008 Edition 1.3 1 Sulfates content of fines in aggre

8、gates Amdt 1 Part 2: Acid-soluble sulfates in fines in aggregates 1 Scope and field of application This part of SANS 5850 specifies a method for determining the acid-soluble sulfates content of fines in aggregates. NOTE Acid-soluble sulfates can be detrimental to roads, to stabilized foundations for

9、 paved areas and to concrete. 2 Normative references The following standards contain provisions which, through reference in this text, constitute provisions of this part of SANS 5850. All standards are subject to revision and, since any reference to a standard is deemed to be a reference to the late

10、st edition of that standard, parties to agreements based on this part of SANS 5850 are encouraged to take steps to ensure the use of the most recent editions of the standards indicated below. Information on currently valid national and international standards can be obtained from the SABS Standards

11、Division. BS 3978, Specification for water for laboratory use. Amdt 3 ISO 3696, Water for analytical laboratory use Specification and test methods. Amdt 3 SANS 3310-1/ISO 3310-1, Test sieves Technical requirements and testing Part 1: Test sieves of metal wire cloth. Amdt 2 SANS 3310-2/ISO 3310-2, Te

12、st sieves Technical requirements and testing Part 2: Test sieves of perforated metal plate. Amdt 2 SANS 197, Preparation of test samples of aggregates. 3 Reagents Use only water that complies with the requirements of ISO 3696 and reagents of analytical reagent grade or (when analytical reagent grade

13、 is unobtainable) of the purest grade available. Use only glassware made of borosilicate glass. Store all calibration solutions in polyethylene containers that have been rinsed with 50 % nitric acid solution prior to use. Amdt 3 SANS 5850-2:2008 Edition 1.3 2 3.1 Hydrochloric acid Hydrochloric acid,

14、 concentrated, analytical reagent of relative density 1,16. 3.2 Dilute hydrochloric acid Concentrated hydrochloric acid (see 3.1) diluted with water in the volumetric proportions 1:1, 1:9 and 1:99. 3.3 Cation exchange resin A suitable cation exchange resin in strong acidic form and of particle size

15、150 m to 300 m. 3.4 Barium chloride solution 10 g of barium chloride dihydrate (BaCl2.2H2O) dissolved in water and diluted to 100 mL. 4 Apparatus 4.1 Test sieves, of nominal aperture sizes 4 750 m, 1 700 m, 425 m, and 125 m and that comply with the requirements of SANS 3310-1 or SANS 3310-2. Amdt 2

16、4.2 Mortar and rubber-covered pestle. 4.3 Stirring device, that consists of combined magnetic stirrer and hot-plate with polytetrafluoroethylene-covered magnetic stirring bars of suitable size. 4.4 Witt filter apparatus, fitted with a Buchner funnel of diameter approximately 90 mm. 4.5 Evaporation d

17、ish, of capacity approximately 100 mL. 4.6 Platinum crucible, ignited and tared. 4.7 Cation exchange column, that consists of a glass column, of length 400 mm and of internal diameter 15 mm, one end of which is provided with a stopcock and the other end with a reservoir of capacity 200 mL. The catio

18、n exchange column is prepared as follows: a) Place 25 mL of the cation exchange resin in a 100 mL beaker, cover the resin with water, and allow to soak for 16 h. b) Insert a glass-wool plug in the glass column, approximately 10 mm above the stopcock. Decant the water in which the resin was soaked, a

19、nd wash the resin into the column by means of a jet of water from a wash bottle. Ensure that the height of the column of resin, measured from the top of the glass-wool plug, is approximately 200 mm. Drain excess water from the column until the water level is approximately 10 mm above the top of the

20、resin. c) Put 100 mL of the 1:1 dilute hydrochloric acid into the reservoir and allow it to run through the column at a rate of approximately 15 mL/min. If the acid emerging from the stopcock is not colourless, wash with further consecutive 50 mL aliquots of the 1:1 dilute hydrochloric acid until th

21、e eluate is colourless. SANS 5850-2:2008 Edition 1.3 3 d) Allow the acid to drain from the column until it just covers the resin. Put 200 mL of water into the reservoir and allow it to drain through the resin until the water level is approximately 10 mm above the top of the resin. e) After every two

22、 tests, re-activate the resin in the column by following the procedures in (c) and (d) above. 5 Preparation of test specimen 5.1 From the test sample (see SANS 197), take a mass estimated to contain approximately 400 g of material that passed the 425 m sieve, dry it to constant mass at a temperature

23、 not exceeding 80 C, allow it to cool, and sieve it on the 4 750 m and 1 700 m sieves. Break up any aggregation of smaller particles (taking care not to reduce the size of individual grains) by placing the portion that passed the 4 750 m sieve and was retained on the 1 700 m sieve in the mortar, and

24、 rubbing it with the rubber-covered pestle. 5.2 Once more sieve this portion on the 1 700 m sieve, add the material that passed the sieve to the quantity that passed the same sieve in 5.1, and sieve the mixture on the 425 m sieve. Place the portion retained on the 425 m sieve in the mortar, rub as i

25、n 5.1, and again sieve thoroughly on the 425 m sieve. Combine the fines (i.e. all the material that has passed the 425 m sieve) and mix well. 5.3 Obtain a portion of mass approximately 100 g of the fines prepared as in 5.2, by means of a sample splitter, or by coning and quartering. So grind this po

26、rtion that the entire mass passes a 125 m sieve. Dry the material to constant mass at a temperature not exceeding 80 C, and cool to room temperature in a desiccator. 6 Procedure 6.1 Weigh out, to the nearest 0,001 g, approximately 10 g of the test specimen (mass a) into a 400 mL beaker and add 200 m

27、L of the 1:9 dilute hydrochloric acid. Place a magnetic stirring bar in the beaker, cover with a cover glass and place the beaker, with contents, on the stirring device. So adjust the speed of the stirrer that all the material remains in suspension, and so adjust the heat that the contents of the be

28、aker are just maintained at boiling point. 6.2 After boiling (with stirring) for 15 min, place the beaker on a warm water bath and, by allowing the beaker to stand undisturbed for 30 min, allow the undissolved material to settle to the bottom of the beaker. 6.3 Place a dry 600 mL beaker in the Witt

29、filter apparatus and place a double layer of glass fibre filter paper of fine texture1)on the Buchner funnel, and wet the paper with a few drops of the aqueous extract (see 6.1). 6.4 Using low vacuum and ensuring that none of the sediment in the beaker is disturbed, filter approximately 150 mL of th

30、e supernatant extract, stir the contents of the beaker until all the sediment is in suspension and rapidly transfer it onto the filter paper. Rinse the beaker three times with successive small quantities of the 1: 9 warm dilute hydrochloric acid, adding the washings to the Buchner funnel after each

31、rinse and ensuring that the filter paper is at no stage allowed to become dry. 6.5 Add approximately 0,5 g of dry filter paper pulp to the filtrate, stir until all the filter paper has disintegrated and again filter through the same glass fibre filter paper. Wash the beaker and filter paper thorough

32、ly with the 1: 99 dilute hydrochloric acid. Boil the filtrate until its volume has been reduced to approximately 50 mL and transfer it quantitatively to the evaporation dish, using the 1: 99 dilute 1) Whatman GF/C or equivalent. SANS 5850-2:2008 Edition 1.3 4 hydrochloric acid to wash out the beaker

33、. Evaporate the contents of the evaporation dish on a water bath until dry, then transfer the dish to an oven maintained at a temperature of 105 C to 110 C and allow to dry for 30 min. 6.6 Add 1 mL of concentrated hydrochloric acid to the contents of the evaporation dish, allow the dish to stand for

34、 5 min, and then add 50 mL of warm water. Place the dish on a water bath, add approximately 0,2 g of dry filter paper pulp, stir until a homogeneous suspension is obtained, and heat for 15 min. Filter the contents of the dish through a fine-textured filter paper2)into a 250 mL beaker. Wash the dish

35、and filter paper with small volumes of warm water until the filtrate has a volume of 100 mL and then allow it to cool to room temperature. 6.7 Transfer the filtrate quantitatively (with water) to the reservoir of the cation exchange column and allow it to drain through the column of resin at a rate

36、of about 15 mL/min into a 500 mL beaker. Finally wash the column with four consecutive 50 mL aliquots of water, adding the washings to the beaker that contains the acid eluate. 6.8 Add 1 mL of concentrated hydrochloric acid to the contents of the beaker, heat to boiling point, and then add (one drop

37、 at a time and stirring the contents of the beaker continuously) 10 mL of barium chloride solution. Boil for 2 min, place in a water bath for 2 h and then allow to cool for 16 h. 6.9 Filter the contents of the beaker through a fine-textured filter paper3), transferring the precipitate quantitatively

38、 to the filter paper by means of a jet of warm water from a wash bottle. Then wash the filter paper and the precipitate with consecutive small volumes of warm water until the filtrate is free from chlorides. NOTE The presence of chlorides can be detected by putting a drop of silver nitrate solution

39、(50 g/L) in approximately 10 mL of the filtrate. If chlorides are present, a milky suspension will be formed. 6.10 Place the filter paper and the precipitate in the ignited and tared platinum crucible, char the paper slowly (without flaming), then increase the temperature and maintain it at just und

40、er 600 C until all carbon has burnt off. 6.11 Ignite the crucible at a temperature of 800 C to 900 C for 30 min, cool to room temperature in a desiccator, and determine, to the nearest 0,001 g, the mass of the residue (barium sulfate, mass b). 6.12 Carry out a blank determination by following the pr

41、ocedures described in 6.1 to 6.11, using the same quantities of reagents but omitting the 10 g of test specimen (mass c). 7 Expression and reporting of results 7.1 Calculate, to the nearest 0,1 %, the acid-soluble sulfates content (expressed as SO3), S, percentage by mass, of the fines (material tha

42、t passed the 425 m sieve) as follows: ( ) 34,3=b-cSa2) Whatman No. 42 or equivalent. 3) See footnote (2). SANS 5850-2:2008 Edition 1.3 5 where a is the mass of the test specimen taken, in grams; b is the mass of barium sulfate found, in grams; and c is the mass of the residue found in the blank determination, in grams. 7.2 Report the mass percentage acid-soluble sulfates (expressed as SO3) to the nearest 0,1 %. SABS