Is there asbestos in concrete?

Concrete is not one of the most common asbestos materials: it is made of cement, aggregate and water. Asbestos may nevertheless have been added to cast-in-place concrete for fire protection reasons, so old concrete cannot be assumed to be asbestos-free. Asbestos can also be found on the concrete surface and in materials connected to it: fillers, floor adhesives, paints, mortars, sealants and asbestos cement parts cast into the concrete. In a building built or renovated before 1994, these materials are tested before the concrete surface is sanded, milled, drilled or demolished.

This article separates the concrete itself from the materials spread on its surface, attached to it or cast inside it, and explains which layer the sample should be taken from.

Why do people suspect asbestos in concrete?

The confusion usually comes from two things. The first is the name: asbestos cement sounds like concrete, but it is a different material. Asbestos cement is a thin sheet or pipe in which asbestos fibre reinforces the cement. Concrete is a solid casting in which cement binds sand and stone. Asbestos cement is covered in more detail in the article asbestos cement.

The second is that a concrete surface is rarely bare. A concrete floor often has filler, adhesive and a floor covering on top, and a wall has filler and paint. When a concrete floor is sanded or milled, the dust comes from all of these layers, not just from the concrete.

What in a concrete structure can contain asbestos?

Cast-in-place concrete

According to Finland's environmental administration building materials guidance, asbestos may have been added to cast-in-place concrete for fire protection reasons. It cannot be seen on the surface, so if an old cast structure is going to be demolished, broken out or sawn, it is worth sampling the concrete as well.

Fillers on the concrete surface

Concrete floors and walls were often levelled with filler before being finished. Old floor and wall fillers are among the most common materials that used to contain asbestos. Read more on the page asbestos in filler and in the article asbestos in wall filler.

Floor adhesives

The adhesives under vinyl sheet, vinyl tiles and parquet are often left on the concrete when the covering is removed. Black or dark brown adhesive on a concrete floor is a typical asbestos suspect. More on this in the articles asbestos in flooring adhesive and asbestos in parquet adhesive.

Paints, mortars and repair compounds

Old paints and coatings on concrete, and the mortars and compounds used for patching, are different products from the original casting, and some of them may have contained asbestos. They are tested separately. See the articles asbestos in paint and asbestos in mortar.

Joints

The joints between precast concrete elements were filled with elastic sealants that could contain asbestos, particularly in the 1960s and 1970s. See the article asbestos in sealants.

Asbestos cement parts cast into concrete

Asbestos cement pipes may have been installed inside or through the concrete, for example drains cast into the slab, and pipe penetrations were sealed with putties that may have contained asbestos. A grey, thin-walled pipe inside the concrete is therefore a different material from the surrounding concrete. Drains are covered in the article asbestos in drain pipes.

What about the aggregate?

The aggregate in concrete is natural stone and gravel. In some places, the bedrock can contain asbestos minerals naturally, as explained in the article asbestos in nature. That is not, however, the reason concrete is normally tested. For a renovation, what matters are the materials on the surface, in the joints and in any cast-in parts.

Is it dangerous to drill or break concrete?

Asbestos in old cast-in-place concrete cannot be ruled out without a sample, even if the surface is bare. Concrete dust is also always harmful to health because it contains quartz, so dust extraction and a respirator always belong with concrete work. When the drill, grinder or breaker goes through filler, adhesive or paint, the dust contains those too. That is why the surface layers of coated concrete are tested before the work starts.

Before demolition work, the materials being removed must be checked for asbestos, even if the structure is mostly concrete. The legislation is covered in the article asbestos legislation in Finland.

Which layer should the sample be taken from?

• Floor: take a sample of every layer from the covering or adhesive down to the filler. A thin piece of the concrete surface is enough to show that all layers are included.
• Wall or ceiling: take a sample of the paint and filler down to the concrete.
• Repaired areas: if the surface has patches or levelling done at different times, take a separate sample from them.
• Joints: take a separate sample of the sealant.
• Cast-in pipe or penetration putty: take separate samples of them.
• Bare concrete: if an old cast-in-place structure is going to be demolished, broken out or sawn, sample the concrete as well. If you can see fibrous or sheet-like material in the concrete, take a separate sample of that.

How to take a sample of the surface layers on concrete

1. Wear disposable gloves and a respirator of at least class FFP3.
2. Lightly mist the sampling spot with a spray bottle to keep dust to a minimum.
3. With a chisel and hammer or a floor scraper, remove a piece of about 2–5 centimetres so that every surface layer comes off down to the concrete. Do not sand and do not use an angle grinder.
4. Drop the piece straight into a zip-lock bag, seal it and put it inside a second bag.
5. Mark the bag with the sample location, for example "living room, floor, adhesive and filler on top of the concrete".
6. Cover the sampling spot with tape and wipe the area with a damp cloth.

More detailed instructions are in the article how to take an asbestos sample.

What does the result mean?

Onelab analyses the sample with a JEOL SEM-EDS electron microscope in accordance with ISO 22262-1, and the result is sent by email, typically on the day the sample arrives. The result tells you whether asbestos was detected in the sample you sent.

• No asbestos detected: no asbestos was detected in the layers of the sample. The result applies to the sampling spot and to the same layer build-up. Other surfaces, repairs and joints are tested separately.
• Asbestos detected: sanding, milling and removing the concrete surface are planned as asbestos work, even if the asbestos is only in a thin adhesive or filler layer. The removal is carried out by a company authorised for asbestos removal work.

If the concrete structure is part of a larger renovation or demolition that requires an on-site asbestos survey, the survey is carried out on site by a qualified surveyor. Onelab is a laboratory, and on-site surveys are handled by our sister brand AsbestiPro.

How much does the analysis cost?

The analysis costs €39.90 + VAT per sample, and the price is the same for 1–100 samples. Orders of more than 100 samples can be priced separately. Postage is not included. You can order the analysis online and send the sample to the laboratory by post.