BS/EN 993-5-2018 pdf download.Methods of test for dense shaped refractory products Part 5: Determination of cold crushing strength.
5 Apparatus
5.1 A mechanical or hydraulic comprcssion testing machine, fitted with a measuring device capable of measuring the load exerted on the test piece to within ± 2 %.
The machine shall be capable of increasing the stress at the rate of 1.0 MPa.s- ± 0,1 MPa•s-’, until the test piece is unable to support the load.
The platens of the machine shall:
a) have a Rockwell hardness value between 58 HCR and 62 NCR;
b) be ground plane to a flatness tolerance of 0,03 mm over the area to be in contact with the test piece;
c) have a surface texture (mean roughness value R) between 0,8 mm and 3,2 mm. This can be checked visually or by feeling with a ‘mean-roughness reference standard such as is used for flat grinding.
The area of the upper platen shall not be greater than 100 cm2, but shall have an area greater than the cross section of the test piece. The upper platen shall work on a seating that will compensate for small deviations from parallelism between the platens and the test piece.
A testing machine whose platens does not comply with the above requirements for size can be used in conjunction with an ancillary adaptor, such as shown in Figure 1, placed centrally between the platens of the machine. The platens of the adaptor shall comply with the machine platens requirements for hardness and flatness given in this clause. They shall have a thickness of at least 10 mm.
The platens should be replaceable to allow re-machining and should not be matted.
5.2 Vernier callipers in accordance with Iso 13385.1, for measurement of test pieces (see 6.3 and
Clause 7)
5.3 Set square
5.4 Drying oven, capable of being controlled at (110 ± 5) °C
5.5 Feeler gauges
5.6 Levelling plate
5.7 AncIllary adaptor (see Figure 1) if needed (see 5.1)
6 Test pieces
6.3.2 Test pieces shall be cut from the item(s) so that the load applied during testing Is in the same direction as the forming pressure during manufacture of the item, when this is known. The original position of the test pieces in the item(s) shall be reported. Test pieces containing cracks or visible defects shall be discarded and this shall also be reported. Both ends of the test piece shall be made plane and parallel, grinding the surfaces where required. Water sensitive material where hydration is expected during the time of test piece preparation and handing shall be machined dry or by using a non- reacting liquid.
To ensure that the top and bottom ends of the test pieces are plane over their entire surface, each end shall in turn be pressured with a load of 3 kN ± 1 kN on to a levelling plate which is lined with carbon or blue paper and hard (liter paper (0.15 mm in thickness). Test pieces that do not show two complete, clearly visible coloured impressions shall be reground (see Figures 2 to 5 for examples of cylindrical test pieces).
A steel straight edge can be used to assist in checking the surfaces. Mortar should not be used to plane the surfaces.
6.3.3 The parallelism of the test pieces shall be checked by four measurements of the height, at the extremities of two perpendicular diameters for a cylinder, or for a cube, along the four edges between the load-bearing faces. The difference between any two of these measurements of height shall not exceed 0,2 mm.
6.3.4 The perpendicularity shall be checked by placing the test piece on a plane surface and using a set square, placed against the side of the test piece, at four positions corresponding to the height measurements. No gap between the side of the test piece and the set square shall exceed 0,5 mm, measured with feeler gauges.
6.3.5 Drying of test piece. The prepared test pieces shall be carefully dried by placing them in a drying oven at (110 ± 5) °C to constant mass. They are then cooled to room temperature and stored in a dry place until the test is performed.
7 Procedure
Measure two perpendicular diameters or medians of each test piece surface to within 0,1 mm. From the arithmetic mean of these four measurements, calculate the initial cross-sectional area A0.
Place the test piece or the ancillary adaptor with the test piece in it centrally between the platens of the machine, without using any packing between the test piece and the platens.
Select the load range so that the expected load at failure is greater than 10% of the load range.
Apply the load smoothly and continuously, increasing the stress at the rate of (1,0 ± 0,1) MPa•s’ until the test piece fails, when it is unable to support the load.BS/EN 993-5-2018 pdf download.