EN 993-2-1995 pdf download.Methods of test for dense shaped refractory products —Part 2: Determination of true density.
3.2
true volume
the volume of the solid material in a porous body
4 Principle
The true density is determined by measuring the dry mass and the true volume of a sample of the material after it has been crushed and ground to such a particle size that as far as possible no closed pores remain. The volume of the ground material is determined using a pycnoineter and a liquid of known density, the temperature of the liquid being controlled or carefully measured.
Unfired refractory products and basic products may require pretreatment, the conditions of which are agreed between the parties concerned.
5 Apparatus
5.1 Pycnometer, of capacity 25, 50 or 100 ml, fitted with a ground stopper having a capillary bore.
5.2 Balance, with an accuracy of ±1 mg.
NOTE An accuracy of ±0.1 mg for the balance is no longer considered a requirement to achieve the reported values. A five-figure balance would be required for this level of accuracy, which is unnecessañly onerous.
5.3 Evacuating equipment, capable of reducing the pressure to a value not greater than 2 500 Pa. and a means of measuring the pressure used.
5.4 Thermostatically controlled bath, capable of being maintained at a temperature from 2 °C to 5 °C above the ambient temperature, ±0,2 °C.
NOTE This accuracy of temperature control is necessary because the method is very sensitive to variations in temperature. Because of the different coefficients of thermal expansion of the vessel and of the liquid, significant errors arise if there are variations in the temperature.
5.5 Test sieve, 63 lIm aperture, complying with the requirements of ISO 565.
5.6 Diying oven, capable of being controlled at (110 ± 5) °C.
5.7 Desiccator.
6 Test material
6.1 In the case of a shaped refractory product, the number of test pieces to be tested per item (brick, shape, nozzle) shall he agreed between the parties and shall be stated in the test report. The same number of test pieces shall be taken from each item, in order to facilitate statistical analysis.
6.2 The test material (test piece) shall be crushed and ground to pass completely through the test sieve (see 5.5).
NOTE In some materials grinding the sample to pass 63 1ni will still leave some closed pores.
6.3 Care shall be taken that the crushing and grinding operations do not introduce foreign matter or moisture into the material.
6.4 Before the test, the materials to be tested shall be dried at (110 ± 5) °C to constant mass, that is to say until two successive weighings made before and after at least 2 h in the drying oven (see 5.6) do not differ by more than 0,1 % of the mass of the test material. Before each weighing, the test material shall be placed in the desiccator (see 5.7) until it has cooled to room temperature.
6.5 Care shall be taken during the preparation of basic refractory materials to prevent any hydration. It is permissible that these materials should be dried at 500 °C; if this is done, the fact shall be stated in the test report.
7 Procedure
7.1 Determination of the initial mass of test material (ni1)
7.1.1 Clean the empty pycnometer (see 5.1) and ensure that it is perfectly dry. It is recommended that leather fingers be used to manipulate the pycnoxneter. Allow it to come to a temperature near to the ambient temperature.
7.1.2 Weigh the cleaned and empty pycnometer with its stopper in position to the nearest 1 mg.
7.1.3 Introduce into the pycnometer a quantity of the dry test material equal to approximately 1/3 of the volume of the pycnomcter, When the pycnometer and its contents have again come to the ambient temperature, weigh it to the nearest 0,000 2 g. The difference in the two weighings is the initial mass of the test material (mi).EN 993-2-1995 pdf download.