Technical Characteristics of Grespania Ceramic Tiles
The following details tests carried out and the results across the stocked range of Grespania Tiles.
Water Absorption Test
In this test the boiling method is used in which the tile is submerged. The coefficient of water absorption is calculated as the quotient of the difference between the wet and dry mass, and the dry mass.
The water absorption result for all non-porcelain Grespania tiles were <3%. For porcelain tiles the results varied from <0.5% to <0.05% depending on the range.
Resistance to Flexion
In this test a force is applied at a predetermined velocity in the centre of the tile, the point of application being in contact with the outer face of the tile.
In all non-porcelain Grespania tiles the result was >40 N/mm2 (newtons per square millimetre). For porcelain tiles the result was always >50 N/mm2.
Resistance to Thermal Shock
In this test a whole tile is subjected to 10 cycles of temperature variation between +15° C and +145° C. The result is either a pass or fail.
This test resulted in a pass for all Grespania tiles.
Resistance to Cracking
The resistance to cracking is determined by subjecting whole tiles to steam at high pressure in an autoclave and examining them with the application of a dye. The result is either pass or fail.
This test resulted in a pass for all Grespania tiles.
Resistance to Staining
In this test the outer face of the tile is kept in contact with several assay solutions. It is then cleaned using specified cleaning methods and examined to detect irreversible changes of appearance. The results are classified between 1 (persistent stain) and 5 (stain eliminated).
The result for all Grespania tiles was 5.
Resistance to Freezing
In this test the tiles are saturated in water then subject to cycles ranging from -5° C to +5° C. All sides of the tile are exposed to freezing for a minimum of 100 freezing / thawing cycles. The result is either a pass or fail.
All Grespania tiles passed this test.
Resistance to Acids, Bases, Cleaning Agents, and Swimming Pool additives.
The tiles are subjected to the action of assay solutions with visual assessment of the attack after a specified period of time. For domestic cleaning and swimming pool products the classes are GA, GB, and GC (glazed tiles) or UA, UB, and UC (unglazed). For weak acids and bases: GLA, GLB, and GLC (glazed) or ULA, ULB, and ULC (unglazed). For concentrated acids and bases: GHA, GHB, and GHC or UHA, UHB, and UHC. The effect is classified from A (no visible effect) to C (with visible effects).
All Grespania tiles had a result of A.
Resistance to Abrasion ( PEI )
In this test the glazed tile is subjected to the rotation of an abrasive material on the surface. The wear is then determined through visual comparison of the tiles with unworn controls. The classification ranges from V (visible defect after more than 12,000 revolutions) to 0 (visible defect by 100 revolutions).
All Grespania tiles received a III, IV, or V rating according to the table below.
Slip Resistance
Since there is no standardised test, a number of methods exist. Of these the following three have been used on Grespania tiles:
a) DIN 51130 (Ramp or R method). The critical angle of slip (which gives the value R) is determined by paving a variable angle ramp on which a person stands wearing boots with a standard sole soaked in oil. The angle at which they start to slip is the critical angle. The value of R (from R9 to R13) is determined by the size of the angle. The greater the angle the larger the R.
b) ASTM C-1028 (static coefficient of friction. Consists of determining the minimum necessary force, tangential to the test surface, to move a standardised slider supporting a load of 22 kilograms. It is carried out on a dry surface and then after saturation with water we thus obtain the dry and wet coefficients fd and fw.
c) ENV-12633 (pendulum method). This test uses a pendulum fitted with a rubber slider, which gives the slip class of the tile according to the angle attained after contact with the tile surface. The classification ranges from 0 (least slip resistant) to 3 (greatest slip resistance).
These tests have been carried out on most porcelain tiles and one white body tile as shown in the table below. Blank spaces in the table indicate no test has been done.
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