METHODS OF PHYSICAL TESTS FOR HYDRAULIC CEMENT

1 SCOPE
This standard ( Part 15 ) covers the procedure for determining the fineness of cement by wet sieving as represented by the mass of the residue left on a standard 45micron IS Sieve.

2 REFERENCES
The Indian Standards listed below are necessary adjuncts to this standard.
3 SAMPLING AND SELECTION OF TEST

SAMPLES
The samples of the cement shall be taken in accordance with the requirements of IS 3535 : 1986 and the relevant standard specification for the type of cement being tested. The representative sample of the cement selected as above shall be thoroughly
mixed before testing.
4 TEMPERATURE
The temperature of the room and the materials shall preferably be maintained at 27 f2”C.

5 APPARATUS
5.1 Sieve
The sieve frame shall be of non-corrodible material and shall be circular 50 f 5 mm in diameter. The depth of the sieve from the top of the frame to the cloth shall be 75 f 5 mm. The frame shall have either side walls 90 f 5 mm in total height or legs of suihcicnt length, 12’0 mm minimum, to allow air circulation beneath the sieve cloth. The sieve frame shall be fitted with 45 micron stainless steel woven wire cloth sieve conforming to IS 460 ( Part 1 ) : 1985. The cloth shall be mounted in the
frame without distortion, looseness or wrinkling. For a sieve fabricated by soldering the cloth to the frame, the joint shall be made smooth to prevent the cement from catching in the joints between the sieve cloth and frame. Two piece sieves shall clamp tightly on the cloth to prevent the cement from catching in the joints between the sieve cloth and the frame. 5.2 Spray Nozzle The spray nozzle ( see Pig. 1 ) shall be constructed with non-corrodible material and shall be of 17’5 mm inside diameter with a central hole drilled in line with the longitudinal axis, and intermediate row of eight holes drilled 6 mm centre to ccntre at an angle of 5” from the longitudinal axis, and an outer row of eight holes drilled 11 mm centre to centre at an angle of IO” from the longitudinal axis. All holes shall be of 0’5 mm diameter. 5.3 Pressure Gauge The pressure gauge shall be of 75 mm minimum diameter and shall be graduated in 0’01 N/mm3 increments and shall have a maximum capacity of 0’2 N/mm’ with a marking at 0’07 N/mm¶. The accuracy at 0’07 N/mm2 shall be 0’005 N/mm2. 5.4 Balance Analytical balance capable of reproducing results within 0’000 2 g with an accuracy of f 0’000 2 g. NOTE — Self indicating balance with equivalent accuracy may also be used. 5.5 Standard Weights 5.6 Oven 6 CALIBRATION OF 45 MICRON IS SIEVE The calibration of the 45 micron sieve shall be made using standard reference material (SRM) from National Council of Cement and Building Materials. Place 1’000 g of the SRM on the clean dry 45 micron sieve and 1 proceed as in 7. The sieve correction factor is the difference between the test residue obtained and the assigned residue value indicated by the electro-formed sheet sieve fineness specified for the standard sample, expressed as a percentage of the test residue. The sieve shall be re-calibrated after every 100 determinations. E.lrample : Residue on 45 micron IS Sieve of 14’0 percent SRM sample Residue for a 1 g sample Residue on Sieve being calibrated 0’140 g Difference 0’105

7 PROCEDURE

Place 1’000 g of sample of the cement on a clean, dry 45 micron IS Sieve. Wet the sample thoroughly with a gentle stream of water. Remove the sieve from under the nozzle and adjust the pressure on the spray nozzle to 0’07 f 0’005 N/mm”. Return the sieve to its position under the nozzle and wash for 1 mitt, moving the sieve with a circular motion in a horizontal plane at the rate of one motion per second in the spray. The bottom of the spray nozzle shall extend below the top of the sieve frame by about 12 mm. Immediately upon removing the sieve from the spray, rinse once with 50 ml of distilled water, taking care not to lose any of the residue, and then blot the lower surface gently upon a damp cloth. Dry the sieve and residue in an oven or over a hot plate ( see Note ), supporting the sieve in such a manner that air may pass freely beneath it. Cool the sieve, brush the residue from the sieve and weigh. NOTE – Care should be taken not to heat the sieve hot enough to soften the solder.

8 CALCULATION

Calculate the mass of the residue of the cement left on the standard 45 micron IS Sieve to the nearest 0.1 percent as follows: Rc= Rs x (lOO+C) where Rc = corrected residue in percent, Rs = residue of the sample retained on the 45 micron IS Sieve in g, and C = sieve correction factor which may be either plus or minus. Example : Sieve correction factor, C = + 33’3 percent Residue from sample being tested, Rs = 0’092 g Corrected residue = 0’092 x ( 100 + 33’3 ) = 12’3 percent

 

 

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