Ceramic Tactile Paving Tile Testing

Ceramic tactile paving tile inspection mainly conducts scientific testing and analysis on the dimensions and appearance quality, physical properties, anti-slip performance, colour and colour difference, stain resistance and chemical corrosion resistance, and water absorption, objectively assessing the product quality grade and issuing a detailed test report, providing a basis for manufacturers' quality control and downstream users' product acceptance.

Testing Items

Dimensions and appearance quality: Including the precise measurement of the length, width and thickness of the tactile paving tile and their allowable deviations. At the same time, it is necessary to check whether the surface is flat, and whether there are the appearance defects that affect the use safety and beauty, such as the cracks, chipped edges and corners, and glaze defects (such as the bubbles and pinholes).

Physical properties: This is the core of the testing, mainly evaluating the mechanical properties of the tactile paving tile. The key indicators include the breaking strength, modulus of rupture (measuring its resistance to the bending), impact resistance and abrasion resistance, to ensure that it can bear the long-term trampling and possible impact loads in the complex pedestrian environments.

Anti-slip performance: Specifically referring to the friction coefficient testing of the raised surface of the tactile paving. By measuring its dynamic friction coefficient under the standard conditions (such as the wet state), it is evaluated whether it can provide sufficient anti-slip force for the visually impaired persons in the wet and slippery conditions such as the rainy and snowy weather, preventing the slipping when walking. This is the key indicator for ensuring the safety.

Colour and colour difference: Detects whether the colour of the tactile paving tile surface meets the design requirements or the relevant standard requirements. By measuring the colour difference value (such as ΔE) with the standard colour plates through a colorimeter, it is ensured that the tactile paving tiles have the obvious colour contrast with the surrounding paving materials, providing the effective visual guidance for the people with the low vision.

Stain resistance and chemical corrosion resistance: Simulates the actual use environment, and detects the resistance of the tactile paving tile surface to the common pollutants (such as the ink, fruit juice and oil stains) and the ease of cleaning. At the same time, it is necessary to evaluate the surface changes after contacting the chemical substances such as the acids, alkalis and salts, ensuring its weatherability and long-term beauty.

Water absorption: The water absorption of the ceramic tactile paving tile is measured by the boiling method or vacuum method. The low water absorption is an important sign of the high-quality ceramic tile, and directly affects the frost resistance, durability and stain resistance of the tile body, especially important in the cold and rainy northern regions.

Radionuclide limits: In accordance with the mandatory national standard (such as GB 6566), the specific activities of the natural radionuclides radium-226, thorium-232 and potassium-40 in the ceramic tactile paving tile are detected, ensuring that its internal exposure index (IRa) and external exposure index (Iγ) meet the requirements of the Class A decorative materials, safeguarding the public health.

Testing Scope

Various directional tactile paving tiles: Mainly detecting the tile bodies with the long strip raised lines (directional tactile paving). The testing scope covers the accuracy of the guiding direction, the standardization of the raised strip dimensions (height, width and spacing), and the straightness of the guiding linearity after the continuous laying, ensuring that it can provide the clear and unambiguous path guidance for the visually impaired persons.

Various warning tactile paving tiles: Mainly detecting the tile bodies with the dot raised points (warning tactile paving). The evaluation focuses on the layout of the raised dot matrix, the height and diameter of the dots, and the combined laying effect with the directional tactile paving, ensuring that the warning signals of "stop, turn and pay attention" can be effectively issued at the positions such as the intersections, slope starts and in front of the obstacles.

Products of the different materials and processes: The testing scope covers the tactile paving tiles made of the ceramic raw materials through the different processes (such as the dry pressing and extrusion), including the unglazed tiles, glazed tiles, porcelain tiles and stoneware tiles. The different materials and firing processes will directly affect their physical and chemical properties, and need to be tested in a targeted manner.

Indoor and outdoor application scenarios: According to the intended application environments of the tactile paving tiles (indoor lobbies, metro station halls or outdoor squares and sidewalks), the testing scope will have the different emphases. The outdoor tiles need to additionally pay attention to the frost resistance, resistance to the sudden changes of the temperature, weatherability and the stronger anti-slip and abrasion resistance requirements.

New product type approval and ex-factory batch inspection: Before the completion of the new product research and development or the batch production of the production lines, the comprehensive type approval testing needs to be carried out. For each production batch, the sampling needs to be carried out according to the standard requirements, and the key ex-factory inspection items such as the dimensions, appearance, breaking strength and water absorption need to be implemented, ensuring the stable product quality.

Engineering quality acceptance and in-service inspection: At the completion acceptance of the projects such as the municipal works and transportation hubs, the on-site sampling inspection of the laid tactile paving tiles is carried out. For the tactile paving systems in use, the situations such as the wear, damage and anti-slip performance decline need to be regularly checked, which belongs to the testing scope of the in-service safety performance.

Testing Methods

Dimension and surface quality inspection method: In accordance with GB/T 3810.2, the measuring tools such as the vernier callipers and steel rulers are used to measure the dimensional deviations at multiple points at the centre and edges of the tile body. The appearance quality is visually inspected by the experienced inspectors at a distance of 1 metre from the tile surface under the specified lighting conditions, and the feeler gauges with the precision of 0.5 mm are used to measure the crack widths when necessary.

Breaking strength and modulus of rupture determination method: In accordance with GB/T 3810.4, the specimen is freely placed on the two supports of the flexural testing machine, and a load is applied to the centre of the tile surface at a uniform speed through the pressure rod until the specimen breaks. The maximum load is recorded, and the breaking strength (N) and modulus of rupture (MPa) are calculated through the formula, evaluating its load-bearing capacity.

Anti-slip performance (friction coefficient) testing method: The pendulum friction coefficient tester or dynamic friction coefficient tester is usually adopted. During the testing, the standard slider of the instrument contacts the wet raised surface of the tactile paving tile, and the dynamic friction coefficient (BPN or COF value) is measured through the pendulum swing attenuation degree or the horizontal pulling force. The specific methods can refer to ASTM E303 or the relevant industry standards.

Abrasion resistance testing method: For the unglazed tiles, the abrasion testing machine is often adopted in accordance with GB/T 3810.6, and after the rotary grinding for a certain number of revolutions under the specified pressure and abrasives, the volume wear amount is measured. For the glazed tiles, in accordance with GB/T 3810.7, the glazed surface abrasion tester is used, and the abrasion resistance grade is rated by observing the number of revolutions required for the glaze to be worn through.

Water absorption determination method: Mainly in accordance with GB/T 3810.3. The specimen is dried to the constant mass and weighed, then immersed in the boiling water and boiled for 2 hours, or placed in a vacuum container for the vacuuming and then immersion, and then soaked and saturated for a period of time. After taking it out and wiping off the surface moisture, it is weighed, and the water absorption is calculated through the mass difference before and after, expressed as a percentage.

Impact resistance testing method: The falling ball impact testing is adopted. A steel ball of the specified mass is dropped freely from the specified height to impact the specific position on the surface of the tactile paving tile (usually near the raised strips), and it is checked whether the tile body produces the cracks, fragmentation or glaze peeling. The impact resistance grade is evaluated by gradually increasing the height or mass.

Testing Standards

Domestic Standards:

1. GB 6566, Limits of radionuclides in building materials

2. GB/T 4100, Ceramic tiles

3. GB/T 3810.1-GB/T 3810.16, Test methods of ceramic tiles (series)

International Standards:

1. ISO 10545, Ceramic tiles — Test methods (series)

2. ISO 13006, Ceramic tiles — Definitions, classification, characteristics and marking

3. ASTM E303, Standard test method for measuring surface frictional properties using the British Pendulum Tester

Note: The applicable standard can be selected according to the product use and customer trade requirements; standards agreed in the contract take precedence over general standards.

Testing Instruments and Equipment

Universal material testing machine: The core equipment for carrying out the mechanical property tests such as the breaking strength and modulus of rupture. Its precision grade needs to meet the standard requirements, and it is equipped with the dedicated ceramic tile flexural test fixtures, which can precisely control the loading rate, automatically record the load-displacement curves and output the maximum breaking force values.

Friction coefficient tester: Including the pendulum friction coefficient tester and the horizontal pulling force dynamic friction coefficient tester. The pendulum tester simulates the "sole slipping" principle to quickly measure the wet-state BPN values; the dynamic tester can more realistically simulate the walking state, measuring the friction coefficient during the continuous sliding process, with the more objective data.

Abrasion testing machines: Divided into the unglazed tile abrasion testing machine and glazed tile abrasion testing machine. The unglazed tile abrasion testing machine uses the steel balls and abrasives to grind the specimen under the pressure; the glazed tile abrasion testing machine (such as the Taber abrasion tester) uses the standard grinding wheels to rotate and rub the glaze surface under the specific loads until the body is exposed, rating the abrasion resistance with the number of revolutions.

Precision measuring tools: Including the digital vernier callipers (precision 0.01 mm), steel rulers, try squares, feeler gauges and flatness measuring instruments. They are used to precisely measure the geometric parameters such as the dimensions, raised strip heights/spacings, edge straightness, squareness and flatness of the tactile paving tile, ensuring that their dimensional and geometric tolerances meet the design and laying requirements.

Colorimeter/spectrophotometer: An instrument for objectively evaluating the colour consistency of the tactile paving tile. By measuring the reflection spectra of the tile surface under the standard light source, the colour difference values (L*, a*, b* and ΔE) with the standard samples are calculated, replacing the subjective judgement of the human eyes, ensuring the colour consistency of the batch products and the contrast with the surrounding environment.

Low-background multi-channel γ-ray spectrometer: A dedicated precision instrument for detecting the radionuclide limits of the ceramic tactile paving tile. It needs to work in a low-background shielding room, can precisely analyse the characteristic γ-ray spectra of the natural radionuclides such as the radium, thorium and potassium in the sample, and calculate the internal and external exposure indices, ensuring the environmental safety of the product.

Environmental test chambers: Including the constant temperature and humidity chambers, freezing chambers and thermal shock testing machines. They are used to simulate the harsh outdoor environments, examining the frost resistance (freeze-thaw cycles), resistance to the high temperature and humidity, and resistance to the sudden temperature changes of the tactile paving tile, evaluating its long-term durability and climate adaptability.