CERAMIC TILE TESTING

Water Absorption method determines the key physical properties of ceramic tiles, focusing on how porous the material is and how it interacts with water, by measuring:

• Water Absorption (% by weight) - how much water the material can absorb when fully saturated
• Apparent Porosity (%) – the percentage of open pores in the material -> the tiny holes that can fill with water
• Apparent Relative Density (g.cm^-3) – how dense the solid portion of the material is -> excludes the open pores
• Bulk Density (g.cm^-3) – how dense the overall material is -> including the open pores

Why is the Water Absorption of ceramic tiles important?

Water Absorption ceramic test method is the key test for ceramic tiles as it determines which Group Classification the tile falls under (see section below for more information on Group Classifications). We can then determine if the tile complies with the specification of the Group Classification for dimensional and surface quality requirements, physical properties and staining or chemical properties. The Group Classification, along with the unique requirements of a particular project and the needs of the client, together influence which tests need to be performed.

The water absorption of ceramic tiles is tested to AS ISO 10545.3:2020 “Ceramic Tiles – Method 3: Determination of water absorption, apparent porosity, apparent relative density and bulk density.” A standard number of specimens (which is determined by the size of the full tile) are dried to constant mass at 110 degrees C for a minimum of 24 hours and then cooled to room temperature. The specimens are weighed dry before being placed within a vacuum chamber, evacuating the air and slowly admitting water to fully immerse the specimens. The specimens remain submerged in the water under vacuum for 15 minutes before they are weighed soaked after patting excess water from the surface with a damp microfibre cloth. They are also weighed suspended in water. The water absorption, expressed as a percentage of the dry mass, is calculated using the dry weight and the soaked weight of the specimens. The suspended weight is used to determine the density.

Modulus of rupture and breaking strength ceramic test method determines bending (flexural) strength by applying a force to the centre of the tiles at a specified rate until failure, measuring both:

• Breaking Load (N) – the force necessary to cause the individual test specimens to break.
• Mean Breaking Strength (N) – The amount of force a material can handle per unit area before it breaks. The breaking strength is obtained by multiplying the breaking load by the ratio of the span to the width, it is NOT the ultimate failure load of the full-size tile.
• Mean Modulus of Rupture (MPa) – the materials bending (flexural) strength (how much the material can bend before it breaks)

Impact resistance (by measurement of coefficient of restitution) – AS 4459.5

Impact resistance ceramic test method determines how well the surface is resistant to impact by dropping of a steel ball, measuring the:

• Coefficient of Restitution (CoR) – ratio of rebound to the height of the dropped steel ball (how much energy is retained after impact to the surface)
• Cahir level (0-5) – a rating system of how resistant the material is to damage (additional included information - not part of standard test method)
• Description of Damage – the type of damage visible on the surface after testing.

Resistance to thermal shock determines the materials ability to withstand rapid temperature changes, by repeatedly exposing the tiles to hot and cold temperatures, then evaluated for visible defects such as:

• cracking
• delamination
• material detachment
• other surface defects

Frost resistance determines the durability of the material after constant freeze-thaw cycling, by water-saturated samples being frozen and then thawed repeatedly, followed by a visual examination to determine if any damage occurs to the surface or edges of the tiles. This test method is often used to access suitability for cold climates where absorbed water can expand and cause cracking.  

Chemical Resistance is tested to evaluate how the material will respond to prolonged exposure to a range of house chemicals, acids & alkalis, then assessed for discolouration, etching, loss of finish or other surface damage. This test method is critical in determining how the material will perform in locations where it is regularly exposed to aggressive substances such as:

• Kitchens/bathrooms -> food acids and/or cleaning products
• Commercial spaces -> frequent cleaning with strong chemicals
• Swimming pools -> chlorinated or saltwater exposure
• Industrial -> potential contact with harsh stronger chemicals

The chemical resistance result is reported as:

• Determination of Class – classification assigned following the relevant evaluation procedure.

Note: The evaluation procedure depends on the tile type (glazed or unglazed), which determines how the assessment is carried out.

Resistance to staining of ceramic tiles evaluates how easily substances can penetrate the materials surface and how easily they can be removed. The results provide an indication of ease of cleaning (cleanability), potential need for sealing and overall fitness for purpose.

This test method determines the resistance to staining by maintaining test solutions and the material in contact, then subjecting them to defined cleaning procedures in attempt to remove the stains. The surface is then visually examined for any residual markings or change in appearance, results are reported as:

• Classification (1-5) – a scale of how easily the staining agent was removed after the defined cleaning procedures (e.g. oil was completely removed following cleaning procedure ‘A’, therefore would be given a ‘Class 5’ classification).

This test method is critical in determining how the material will perform in locations where it is regularly exposed to potential staining substances such as:

• Benchtops & joinery -> high risk of exposure to oils, acids or grimy substances
• Flooring -> particularly high-trafficked areas
• Commercial spaces -> where spills are more frequent

Small colour difference test method measures the colour consistency between tiles and/or batches, which are designed to be of uniform and consistent colour.

Slip Resistance testing measures the slip resistance of ceramic tile surfaces under dry and/or wet conditions to determine their suitability for pedestrian areas. AS 4586:2013 Slip resistance classification of new pedestrian surface materials is typically used to classify new tiles using methods such as wet pendulum or dry floor friction testing, while AS 4663:2013 Slip resistance measurement of existing pedestrian surfaces is used to measure slip resistance on installed surfaces.

Slip resistance is a key safety parameter for floor tiles, especially in wet or high-traffic areas such as bathrooms, kitchens, commercial spaces, and outdoor walkways determined by measuring the:

• British Pendulum Number (BPN) – the individual result of each test site during the pendulum test method.
• Slip Resistance Value (SRV) – the mean measurement of the 5 required BPN results to determine how slip resistant a tile surface is.
• P-Rating – classification system derived from SRV results (for new pedestrian surface only)
• Suitable locations – a guide to the location suitability of the tile according to HB198.

Find out more about slip resistance (link to slip page)

Slip Resistance after accelerated wear evaluates how the slip resistance of ceramic tiles changes after simulated long-term wear. The tile surface is subjected to controlled wear processes that mimic the effects of traffic, routine cleaning and general wear over time, after which slip resistance is then re-measured.

For ceramic tiles, this test is useful for textured or coated surfaces that may lose their slip-resistant properties. By assessing slip resistance after accelerated wear, the test provides an indication of how well the tile is likely to maintain safe traction throughout its service life, helping designers and specifiers select tiles that may remain compliant.

Find out more about slip resistance after accelerated wear HERE.