SANS 5748-2010 Specific surface of cement《水泥的比表面积》.pdf

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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 978-0-626-24074-5 SANS 5748:2010Edition 2.1SOUTH AFRICAN NATIONAL STANDARD Specific surface of cement Published by SABS Standards Division 1 Dr Late

4、gan Road Groenkloof Private Bag X191 Pretoria 0001 Tel: +27 12 428 7911 Fax: +27 12 344 1568 www.sabs.co.za SABS SANS 5748:2010 Edition 2.1 Table of changes Change No. Date Scope Amdt 1 2010 Amended to delete a withdrawn standard. Foreword This South African standard was approved by National Committ

5、ee SABS SC 59A, Construction standards Cement, lime and concrete, in accordance with procedures of the SABS Standards Division, in compliance with annex 3 of the WTO/TBT agreement. This document was published in March 2010. This document supersedes SANS 5748:2006 (edition 2). A vertical line in the

6、margin shows where the text has been technically modified by amendment No. 1. SANS 5748:2010 Edition 2.1 1 Specific surface of cement 1 Scope The standard describes a method to determine the specific surface of cement. 2 Normative reference The following referenced document is indispensable for the

7、application of this document. All normative documents are subject to revision and, since any reference to a normative document is deemed to be a reference to the latest edition of that document, parties to agreements based on this document are encouraged to take steps to ensure the use of the most r

8、ecent edition of the normative document indicated below. Information on currently valid national and international standards can be obtained from the SABS Standards Division. SANS 5747 (SABS SM 747), Density of cement. Amdt 1 3 Apparatus 3.1 Description 3.1.1 Glass U-tube, of uniform cross-section.

9、The U-tube has two permanent timing marks, A and E, and two permanent equilibrium marks, B and C, as shown in figure 1. The mark, D, is for the calibration of the portion CD of the tube. The apparatus is so mounted on a board that both limbs of the U-tube are vertical, and that any difference betwee

10、n the levels of the equilibrium marks B and C does not exceed 0,2 mm. After calibration (see 3.2) the tube is filled with a liquid (either paraffin or water) until the bottoms of the menisci coincide with the equilibrium marks. The level of the liquid is checked frequently. 3.1.2 Stainless steel per

11、meability cell. A medium-textured filter paper, X, of diameter about 25 mm, is inserted in the permeability cell on top of the perforated plate. The cell is connected to the U-tube by means of stoppers and a T-piece with a stopcock, F. The connections are air-tight when the stopcock is closed. 3.1.3

12、 Plunger. 3.2 Calibration 3.2.1 Determine the mean diameter of the portions AB and CD (see figure 1) of the U-tube by filling each of these two portions (in turn) with a liquid and measuring, to an accuracy of 0,1 mL, the volume of liquid required to fill each portion. SANS 5748:2010 Edition 2.1 2 3

13、.2.2 Measure, to the nearest 0,1 mm, the distances AE, AB, and CD. 3.2.3 Calculate the mean diameter (to the nearest 0,1 mm) as follows: +aaD12=10 where D is the mean diameter, in millimetres; a1is 10 volume of ABlength of AB; a2 is 10 volume of CDlength of CD. 3.2.4 Determine the density of the liq

14、uid in the U-tube to the nearest 0,01 g/mL. 3.2.5 Calculate the instrument constant from the formula: d g Ch D Lh312e40 =(1 )logwhere C is the instrument constant; d is the diameter of the bed of cement, in millimetres (i.e. inside diameter of the permeability cell); is the porosity of the bed of ce

15、ment (i.e. 0,475) (see clause 4); D is the diameter of the U-tube, in millimetres (see 3.2.1); g is the gravitational acceleration, in metres per second squared; is the density of the liquid in the U-tube, in grams per cubic centimetres (see 3.2.4); is the viscosity of the air, in Newton seconds per

16、 square metre; L is the depth of the bed of cement, in millimetres (i.e. 10 mm) (see clause 4); h1and h2is the height of the higher and lower timing marks, respectively, above the equilibrium level, in millimetres (i.e. see distances AB and EB in 3.2.1). NOTE The international value for g is 9,806 6

17、5 m/s2and values for the viscosity of air, , at different temperatures are given in table 1. SANS 5748:2010 Edition 2.1 3 Table 1 Viscosity of air 1 2 Air temperature Viscosity of air C 105Ns/m216 1,788 18 1,798 20 1,808 22 1,818 24 1,828 26 1,837 28 1,847 30 1,857 32 1,867 34 1,876 4 Procedure 4.1

18、Perform the test at an air temperature of 24 C or record the ambient air temperature and correct the result as prescribed in clause 5. 4.2 From the density of the cement as given in table 2, determine the mass of cement required to give a porosity of 0,475 when compacted. Insert the correct mass of

19、cement into the permeability cell (that contains the filter paper on top of the perforated plate (see 3.1) and level off the surface of the cement by gently shaking the cell from side to side. Amdt 1 NOTE The porosity is taken as the ratio of the volume of the pore space to the total volume of the b

20、ed of cement. Table 2 Mass of cement required to form a bed 1 2 3 4 5 6 7 8 9 10 11 Density Mass of cement required g/cm3g 2,8 7,45 7,48 7,50 7,53 7,56 7,58 7,61 7,63 7,66 7,69 2,9 7,71 7,74 7,77 7,79 7,82 7,85 7,87 7,90 7,93 7,95 3,0 7,98 8,01 8,03 8,06 8,09 8,11 8,14 8,17 8,19 8,22 3,1 8,25 8,27 8

21、,30 8,33 8,35 8,38 8,41 8,43 8,46 8,49 3,2 8,51 8,54 8,57 8,59 8,62 8,65 8,67 8,70 8,73 8,75 NOTE The values given are to obtain a bed 10 mm deep with a diameter of 25,4 mm and a porosity of 0,475. 4.3 Compact the cement by dropping the cell four times from a height of about 10 mm on to a wooden ben

22、ch, and then insert the plunger and push it home very slowly until its collar is in contact with the top of the cell. Withdraw the plunger slowly with a twisting motion, but ensure that it is not twisted while it is in contact with the cement bed. lf inspection shows that the cement bed has been dis

23、turbed, discard the cement and refill the cell. SANS 5748:2010 Edition 2.1 4 4.4 Open the stopcock, F, and connect the cell to the U-tube, taking care that the bed is not disturbed and that an air-tight seal is obtained. Carefully raise the level of liquid in the righthand arm (see figure 1) of the

24、U-tube by drawing out air through the stopcock. Close the stopcock when the level of the liquid is about 30 mm above the upper timing mark A. Using a stopwatch measure, to an accuracy of 1,0 s, the time of travel of the bottom of the meniscus between the two timing marks, A and E. 4.5 Repeat the tim

25、ing procedure on the same test sample, then test a second test sample in the same way, and use the mean of the four values thus obtained in the calculation. Change the filter paper after every six determinations. 5 Calculation 5.1 Calculate the specific surface of the cement as follows: =SCtPwhere S

26、 is the specific surface of the cement, in square centimetres per gram; C is the instrument constant (see 3.2.5); P is the density of cement, in grams per cubic centimetre (see 4.2); t is the average time, in seconds, for the meniscus of the liquid in the U-tube to travel between the two timing mark

27、s. 5.2 If the test was performed at a temperature other than 24 C, apply the relevant correction given in table 3. 5.3 Report the specific surface to the nearest 50 cm2/g. Table 3 Temperature correction per 1 000 cm2/g 1 2 3 4 5 6 7 8 Temperature Temperature Temperature Temperature C Correction C Co

28、rrectionC CorrectionC Correction16 +10 20 +5 24 0 28 5 17 +9 21 +4 25 1 29 7 18 +8 22 +2 26 3 30 8 19 +6 23 +1 27 4 31 9 SANS 5748:2010 Edition 2.1 5 Figure 1(a) Perforated plate SANS 5748:2010 Edition 2.1 6 Figure 1(b) U-tube Figure 1 Specific surface apparatus SABS SABS Standards Division The obje

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