On-Site controls on natural stone products

Like any construction product, natural stone requires some controls that ensure its qualities.

The controls carried out on granite products are, on the one hand, those relating to manufacturing, such as the CE Marking which we have already discussed in other entries and, on the other, on-site reception controls which are the responsibility of its Construction Management.

On-site reception controls

In order to use natural stone correctly, a control of the products received on-site is required.

The on-site product must be grouped into batches, and each item that comes from a material constitutes a batch. From each batch we will randomly extract a sample and, according to the level of inspection that we want to apply, we will establish acceptance and rejection criteria for the products.
For example, from a batch with X parts, if we extract a sample of Y parts, how many parts would we accept as non-conforming in order to validate the batch? For this, there are reference standards that indicate the criteria to apply in each case, such as the ISO 2859-1:2012.

With all of this, the recommended controls to take should be a set of tests that are carried out quickly so as to not interrupt the normal running of the works. As minimum, we recommend the following:

• Dimensional controls: At least the length, width and thickness of the parts must be controlled, verifying whether they comply with the dimensional tolerances indicated in the UNE-EN standard relating to each product.
• Aspect: This control is extremely important for the good end of the works. A sample consisting of a number of parts representing the extreme and average characteristics of the stone from the point of view of its colour, texture, discontinuities, etc. must be placed in an area that is clean and exposed to lateral natural light.
• Absorption test and bend-resistance test: These will be conducted in a laboratory and consist of two quick tests that will give an idea of whether the material supplied represents the one declared on the CE label.

It is worth mentioning that these controls benefit both the Construction Management of each work, who will have calculation parameters that are truly representative of the material, and the manufacturers, who will verify the quality of our products. And, of course, the end user, who will acquire a product that was built with controlled materials.

Eva Portas Fernández
Department of Consultancy and Design
TECHNOLOGICAL CENTRE OF GRANITE IN GALICIA