Ceramic Tiles - Methods of the test, Sampling and Basis of Acceptance, Part 10: Determination of frost resistance (see IS 13630: Parts 1 to 15)
2006 الطبعة

Prior to frost testing, tiles must be oven-dried at 110 ± 5°C until their mass variation is less than 0.1% over 24 hours, with the dry mass recorded as M₁. Impregnation is performed using progressive capillary water absorption as the standard method. Tiles are immersed in water maintained at 15 ± 3°C and drained before the temperature falls below 5°C. The temperature is then cycled from +15 ± 3°C down to -15 ± 3°C within 2 hours ± 20 minutes. To ensure consistency, water evaporation during cooling is controlled. If tiles are drained above 5°C, they are held at 15 ± 3°C for 2 hours ± 20 minutes, re-immersed at the same temperature for another 2 hours ± 20 minutes before starting the freeze-thaw cycles. Finally, water content after testing is calculated using the formula Wc₂ = ((M₃ - M_A)/M_A) × 100, where M₃ is the wet mass after testing and M_A is the dry mass after testing.

The standard mandates performing 50 complete freeze-thaw cycles on the tiles. Each cycle involves subjecting the tiles to temperatures fluctuating between +15°C and -15°C, with all tile surfaces exposed to the freezing environment. Each full cycle lasts 6 hours following the temperature-time profile specified in the standard. After completion of the 50 cycles, tiles are inspected for any damage on their glazed or designated surfaces as well as edges to assess frost durability.

During testing, the freezer must cycle tile temperatures between +15 ± 3°C during immersion and -15 ± 3°C during freezing. The cooling phase requires the temperature to reach -15 ± 3°C within 2 hours ± 20 minutes. After freezing, tiles are held at +15 ± 3°C for a thawing period of 2 hours ± 20 minutes. Each complete freeze-thaw cycle must be completed within 6 hours. The air velocity inside the freezer should not exceed 4 m/s to maintain uniform temperature distribution throughout the test specimens.

Post-test evaluation involves a thorough visual examination of tiles covering a minimum area of 0.25 m² with at least 10 whole tiles tested. Tiles must be cleaned of dust before testing, and any existing defects such as cracks, crazing, holes, or chipped corners should be permanently marked prior to testing for reference. After the 50 freeze-thaw cycles, tiles are inspected for new or worsened damage including cracks, surface crazing, spalling, or edge chipping. The assessment compares pre- and post-test conditions to determine the extent of frost-induced deterioration.

The frost resistance test requires a freezer capable of maintaining controlled temperature cycles with uniform air circulation. Thermocouples must be embedded centrally within the test tiles to accurately monitor tile temperature within ±0.5°C. A temperature recording system is needed to track both tile and air temperatures during tests. The setup should allow spacing of tiles to ensure air flows around all surfaces. An automated or manual freeze-thaw cycling system should maintain the specified temperature-time curve with cycles lasting 6 hours each, enabling consistent and repeatable freeze-thaw exposures.