LABORATORY TESTS

What these tests are and who signs them

Each document on this page is a tile test results report issued by Elabora, a laboratory listed in the Register of Testing Laboratories of the Junta de Andalucía (the Andalusian regional government) under number AND-L-155. Each report carries its number, the sampling date, the signature of the laboratory director and the standard method applied in each test.

We publish the full reports, not a summary. If you are writing a project specification or justifying a line item to the architect or site supervisor, you can download the PDF and cite it by its report number.

Slip resistance: class 3 for hydraulic terrazzo

This is the property that matters most in a floor, and the only one imposed by the Spanish Building Code (CTE) in its Basic Document DB-SUA 1. The Rd value is obtained with the friction pendulum test described in the Spanish standard UNE 41901:2017 EX, and it translates into four classes:

Our 20×20 cm hydraulic terrazzo achieved a PTV of 59.5 in the wet test carried out at 20 °C (individual values from 55 to 60). It is therefore in class 3: the highest level on the scale and the one the CTE requires for outdoor areas, swimming pools and showers. This is recorded in report no. 4718.

An important and honest caveat: the pendulum test needs a sliding area of 124×76 mm. On small pieces, such as the 15×5 cm terracotta tile, it cannot be carried out on a loose tile and has to be done on a sample that has already been laid.

Water absorption of each material

Absorption determines how a tile behaves with stains and, above all, with frost: water held in the pores expands as it freezes and breaks the tile from the inside. These are the coefficients measured:

To put the figures in context: porcelain stoneware stays below 0.5 %. Terracotta and zellige are porous by nature, which is why they need a water-repellent treatment; terrazzo, at 6 %, behaves differently.

Which standard applies to each product

Not all our products are governed by the same standard, and it is best not to mix them up (UNE-EN standards are the Spanish editions of the European EN standards):

• Cement tiles and hydraulic terrazzo are concrete paving tiles: they are tested to UNE-EN 1339 (requirements and test methods) and, in the case of terrazzo, also to UNE-EN 13748-1/2. They are not ceramics: they are not fired, they set.
• Zellige and terracotta are ceramic tiles: they are tested to the UNE-EN ISO 10545 series—dimensions (-2), absorption (-3), bending strength (-4), abrasion (-7), chemical resistance (-13) and staining (-14)—and classified under UNE-EN 14411.

It is a distinction that is often overlooked. Asking for ceramic marking on a cement tile, or for the concrete classification on a zellige tile, leads to comparing figures that are not comparable.

Other results recorded in the reports

• Abrasion resistance of zellige: visible defects appear at 750 revolutions, which places the tile in class 3 under UNE-EN ISO 10545-7.
• Bending strength of terracotta: between 8.7 and 10.3 N/mm² over ten tiles, with a 130 mm span between supports (UNE-EN ISO 10545-4).
• Chemical resistance of terracotta: classes UA, ULA and UHA with no visible effect, i.e. class A against household cleaning products and against acids and alkalis at both low and high concentrations (UNE-EN ISO 10545-13).
• Stain resistance of terracotta: class 2 (UNE-EN ISO 10545-14). Removing the stain takes a solvent, which is precisely why terracotta is always treated with a water-repellent.

The reports, one by one

You can download any of them from the links at the top of this page. If you need a test on a specific format or model that is not listed here, write to us and we will arrange it.

The products tested are in our cement tile, terrazzo, zellige and terracotta catalogues.