Review of the 8th symposium "Der Bausachverständige"
At the 8th symposium "Der Bausachverständige" the topics asbestos and radon were in the focus. Asbestos continues to be one of the most important building pollutants to be found in existing buildings. Radon is a naturally occurring, radioactive noble gas that is produced in the soil by the decay of uranium. When circulating in the soil, the gas can penetrate buildings and thus lead to an increased radiation exposure of the inhabitants. That is why it is particularly important that building experts are always up to date on this topic.
As a laboratory for asbestos analysis, we naturally provided information and held discussions on the subject of asbestos in particular at our stand at the symposium.
In addition, we listened to the lectures of the symposium in order to keep up to date with the current discourse on the subject of asbestos. Below are some impressions from and thoughts on conference contributions:
Asbestos in building stock
Andrea Bonner from BG BAU, who is currently based at the Federal Ministry of Labour and Social Affairs, explained in her lecture the dangers that asbestos can pose during work on existing buildings. Asbestos-containing materials lurk in buildings in many places: This starts with heat protection and insulation, for which asbestos board was used, and continues with asbestos-containing floor coverings and their adhesives through to concealed asbestos products such as tile adhesives and fillers.
The problem is that work on products containing asbestos is prohibited. The so-called ASI work is an exception.
ASI work: Demolition, repair and refurbishment
The abbreviation ASI stands for demolition, repair and refurbishment:
- Demolition: complete removal of asbestos-containing materials in all areas. If several materials are present in the composite, such as Floor-Flex panels and the black bitumen adhesive, all materials must be completely removed.
- Repair: functional maintenance of a building. Activities on materials containing asbestos are also possible. If surface removal of asbestos-containing materials is necessary, recognised low-emission processes must be used.
- Refurbishment: The long permissible spatial separation or coating of weakly bound asbestos products is no longer permissible. According to current case law, the ban on overlapping also applies here.
Asbestos regulations and standards
With regard to standards and regulations, reference was again made to the ongoing National Asbestos Dialogue. A draft bill for the new version of the Ordinance on Hazardous Substances is to be submitted here by the beginning of 2020. TRGS 519 will also be revised. An exposure-risk matrix is to be introduced in future. The deadline for this was set for September 2019. The VDI Guideline 6202 Part 3, Polluted structural and technical installations - asbestos (greenprint: October 2019) will also be reprinted.
Asbestos and analytical detection
Jürgen Göske from the Zentrum für Werkstoffanalytik Lauf demonstrated the possibilities and limits of the analysis of asbestos minerals at the symposium "Der Bausachverständige". Asbestos and also artificial mineral fibres are fibrous. Fibres are linear structures that are thin and usually flexible in relation to their length. In analytics, the ratio of length to diameter is usually between 10:1 and 3:1.
Distinguishing artificial mineral fibres from asbestos
Artificial mineral fibres, also known as glass wool or glass fibres, do not only show a roundish shape and parallel edges as well as a lack of cleavage. One of their characteristic features are melting beads that originate from the production process. This and their variable chemistry make them easily distinguishable from asbestos.
What is asbestos?
Asbestos is not a mineral name, but a technical term for a group of six different minerals. The name derives from the Greek "asbestos" for "imperishable". These six minerals were often used because of their technically useful properties. Above all white asbestos, the serpentine mineral Chrysotil. This is also the only truly webable asbestos. The other 5 asbestos belong to the mineral group Amphibole. Of these, amosite (brown asbestos) and crocidolite (blue asbestos) are the technically used asbestos. Tremolite, anthophyllite and actinolite are rarely found in technical products.
Asbestos and laboratory analysis
As modern laboratory methods, the scanning electron microscopy with energy dispersive analytics (SEM / EDX) and the X-ray diffractometry (XRD), which is often propagated by the lecturer, were mentioned at the symposium "Der Bausachverständige". Yes, the XRD can reliably identify individual mineral phases. Unfortunately, we did not learn anything about the detection limits in the lecture. We assume that especially in the areas where REM/EDX is really uncertain about the true nature of an observed fiber, because there are simply too few fibers on the specimen, the XRD will also find nothing.
There are good preparative techniques that can separate asbestos fibres from the matrix and enrich them if the contents are too small or the matrix is too disturbed. Even if there are certainly cases where the much more expensive XRD analysis could help, nobody would probably want to bear the costs. In addition, the asbestos fibres sought must neither be too small nor present in too small a quantity in the sample.
The symposium "The building expert" was for us an exciting event with informative technical contributions - also on the topic radon. Beside the lectures also the numerous interesting contacts and discussions pleased us, which resulted in our conditions. Thanks to all who visited us.