EN 993-1-1995 pdf download.Methods of test for dense shaped refractory products — Part 1: Determination of bulk density, apparent porosity and true porosity.
3.9
true porosity (7r)
the ratio of the total volume of the open and closed pores to the bulk volume of the material, expressed as a percentage
NOTE (onscquentIv, the true porosity is the sum of the apparent porosity and the closed porosity.
3.10
dense shaped refractory product
a product having a true porosity of less than 45 % (V/V
4 Principle
4.1 The following are determined by weighing: the mass of a dry test piece, then its apparent mass when immersed iii a liquid with which it has been impregnated under vacuum, and then its mass in air while still soaked with the liquid.
From these values and from the true density of the material, determined by the method specified in EN 993-2, its bulk density, apparent porosity and true porosity are determined by calculation.
4.2 The precision of the results does not require any correction to be made for the fact that weighings are carried out in air, not in a vacuum.
5 Apparatus and materials
5.1 Drying men, capable of being controlled
at (1 10 ± 5) °C.
5.2 Balance, with an accuracy of± 0,01 g.
5.3 Bridge, to be placed over the load-bearing scale pan of the balance (see 7.3), if a two-pan balance is used.
5.4 Evacuating equipment, capable of reducing the pressure to a value no greater than 2 500 Pa and a means of measuring the pressure used.
5.5 Thermometer, accurate to ± 1 °C.
5.6 Immersion liquid, for materials that do not react with water, the immersion liquid may be cold distilled water. For materials that are sensitive to contact with water, a suitable organic liquid shall be used.
NOTE For example. distilled paraffin may 1w used for hydratable materials.
5.7 Desiccator.
6 Number and shape of test pieces
6.1 The number of items (for example, bricks, shapes, nozzles) to be tested shall be determined by agreement between the interested parties.
6.2 The number of test pieces to be tested per item shall be agreed between the parties; it shall be stated in the test report. If the test pieces are cut out of bricks or blocks, the same number shall be cut from each one, in order to facilitate statistical analysis.
6.3 Test pieces shall be cut in the form of prisms or cylinders. The bulk volume of a test piece shall be not less than 50 cm3, and shall be not more than 200 cm3. The ratio of the longest to the shortest dimension of a test piece shall not exceed 2: 1.
NOTE Where it is not possible to obtain the given size and volume from the item, test pieces of other dimensions and volume may he used by agreements between parties. and are to be reported.
6.4 Any test piece showing cracks shall be eliminated, since these might falsify the determination of the bulk volume.
7 Procedure
7.1 Determination of mass of dry test piece (m1)
Dry the test piece at (110 ± 5) °C to constant mass, i.e. until two successive weighings made before and after at least 2 h in the oven do not differ by more than 0,1 %.
Before each weighing. place the test piece in a desiccator until it has cooled to room temperature. Weigh each test piece to the nearest 0,01 g. The mass determined is the mass of the dry test piece (mi).7.2 Soaking of test piece
Carry out a check test to ensure that the apparatus will hold a vacuum. Place the cooled and dried test piece in an airtight vessel. After sealing the vessel. evacuate it until a pressure of not more than 2 500 Pa is attained; maintain this vacuum for at least 15 mm. In order to ensure that all the air has been removed from the open pores, isolate or disconnect the vessel from the vacuum pump and check that pressure does not rise through any degassing of the test piece. Reconnect the vessel to the vacuum pump and progressively introduce the immersion liquid so that, after 3 mm, the test piece is covered by about 20 mm of liquid. Maintain this reduced pressure for 30 mm, then switch off the pump and open the vessel. Wait a further 30 mm to ensure that the liquid penetrates into all the open pores.
NOTE Certain fine porositY materials such as refractories containing carbon and some clay products may require longer periods of evaporation.
7.3 Determination of apparent mass of immersed test piece (m2)
Suspend the test piece by a thin thread from the load-pan suspension point of a hydrostatic balance and weigh it while completely immersed in a quantity of the immersion liquid, contained in a beaker standing on the bridge, if used. In this way, the apparent mass of the immersed test piece is obtained (m2). The weighing shall be made to the nearest 0,01 g. Determine the temperature of the immersion liquid to an accuracy of± I °C.
7.4 Determination of mass of soaked test.EN 993-1-1995 pdf download.