Review of the DCONex 2019: Building pollutants & construction in existing buildings
On 30 and 31 January the CRB team took part in the DCONex 2019 in Essen. At the congress for pollutant management and remediation with accompanying trade exhibition, building pollutants were once again high on the agenda. The importance of this topic was reflected in the renewed growth in the size of the event: the Pollutants Fair attracted considerably more participants than in previous years and offered an even more varied programme with contributions, some of which took place in three halls at the same time.
This year CRB was represented for the first time with its own stand at DCONex. Here the visitors could not only marvel at different exhibits (such as different asbestos minerals), but also personally talk to our team.
Of course, we also used the congress to inform ourselves about current topics in the field of pollutant management and in particular about the handling of asbestos. Below are some impressions and thoughts on congress contributions:
Pollutants during construction in existing buildings
We usually associate the topic "building" with a new building. In the process, construction is carried out much more frequently in existing buildings. This includes conversion, refurbishment, modernisation and upgrading of existing buildings. It is also this area of construction in which one frequently has to deal with (obstructed) building pollutants.
At DCONex 2019, Peter Schurkraft explained the challenges that building pollutants pose for state building owners. There are around 8,000 state-owned buildings in Baden-Württemberg. Of these, around 4,500 were built between 1950 and 1990 - in other words, during the period considered critical with regard to building pollutants. In addition, there are older buildings that were renovated or refurbished during this period.
Depending on the motivation, whether the building is to be demolished, renovated or technically upgraded, or whether there is acute danger to the users, appropriate strategies must be developed. This probably reveals a problem in architectural studies: most people want to design. Building in existing buildings is probably far less popular and the subject of building pollutants is treated somewhat too neglected.
Hans-Dieter Bossemeyer of Wessling GmbH gave an overview of the dangers which can lurk in the building stock in his congress contribution. This was followed by a quick flight over the various building pollutants and their significance. Asbestos not only plays a role as a pollutant in existing buildings and in demolition, but should also be kept in mind when recycling building materials.
Hans-Dieter Bossemeyer from Wessling GmbH
Measures from the National Asbestos Dialogue
Reporting on the National Asbestos Dialogue has already established itself as an integral part of DCONex in recent years. Andrea Bonner from BG BAU gave an overview of the results so far and an outlook. For example, a specialist database on building pollutants and an information platform on asbestos are to be created. In addition one wants to seize the exposition particularly with crafts work in the range plasters, tile adhesives and fillers.
The National Asbestos Dialogue will also be continued this year. Current topics include the revision of the Hazardous Substances Ordinance (GefahrstoffV) and TRGS 519. Dr. Birgitta Höwing from Wessling GmbH informed us about the current state of affairs. In addition, the LASI guidelines on the Ordinance on Hazardous Substances LV 45 are to be published in an updated form - taking into account current judgements, e.g. with regard to the ban on masking (Magdeburger Morinolfugen judgement).
Further information: www.asbestdialog.de
Recycle building materials despite harmful substances?
Increased recycling of building materials is an important step towards conserving resources and establishing a sensible recycling economy. But how should we deal with the many building pollutants? How do we ensure, for example, that asbestos disappears from the cycle once and for all?
First, of course, the pollutants in the building must be identified. Martin Kessel from Arcadis Germany GmbH reported at DCONex 2019 on the work on VDI Guideline 6202 Part 3: Polluted structural and technical installations - Investigation and evaluation - Asbestos. This planned VDI guideline is derived from the 2015 discussion paper of GVSS and VDI on concealed asbestos products such as plasters, tile adhesives and fillers. A first draft of this new guideline was announced for the first half of 2019.
Hans Albrich from GIU GmbH also dealt with the recycling of material from dismantling in his presentation. He dealt with the new VDI guideline 3876 and its application in practice with the question of whether LAGA M23 is still up-to-date with regard to the definition of asbestos-free material.
Since VDI Guideline 3876 was only published in November 2018, no practical experience has yet been gained in this respect. This guideline is located in a conflict zone between two legitimate interests:
- On the one hand, old building materials are to be recycled within the framework of a good environmental service branch, thus conserving natural resources.
- On the other hand, protection against asbestos and other pollutants that may be present in the recycled building materials must be guaranteed.
What is considered to contain asbestos?
The value of 0.1% by mass is mentioned in the Hazardous Substances Ordinance. However, since the hazard potential of asbestos does not depend on the mass but on the number of respirable fibres, the significance of this value is unclear: Does it represent the boundary between hazardous and non-hazardous waste? Or was this value rather due to the detection limits of the analytical methods used?
Here the boundary between recyclable and non-recyclable construction waste is missing. The problem with asbestos is that it occurs almost everywhere in building materials. The fibre was not always deliberately added, but in some cases crept in through the back door in the wake of an unsuspicious material. The more precise the analytical methods become, the more often these asbestos is encountered.
Instead of making a distinction between asbestos-containing and asbestos-free, a statement could also be made on the usability of asbestos. For example, whether a material is low in asbestos and is approved for certain uses under certain conditions. Since the pollutant is inhaled but does not diffuse through other materials, a risk-based approach could help.
We now have a small arsenal of analytical methods at our disposal. From ISO 22262-2 :2014-02 and VDI 3866 Part 5 Annex B :2017-06 with their 0.001 mass%, the BIA/IFA method 7487 with 0.008 mass% and VDI 3876 with 0.005 and 0.001 mass% respectively as detection limit. However, these detection limits are only estimated. The detection limits are not determined. In addition to the device parameters, the detectability also depends subjectively on the tester. The determination limits can hardly be determined.
Asbestos and recycled material
The new VDI guideline 3876 is intended to define the procedure for the preparation of samples from construction and demolition wastes as well as recycling materials obtained from them, which were taken in accordance with DIN 19698 or LAGA PN 98, if these are to be qualitatively tested for asbestos. It also specifies a quantitative method for determining the asbestos content of the samples.
However, here the questions arise: Is a positive result to be equated with an assessment as hazardous waste? And why is a quantitative method introduced if no limit value exists?
In addition, there is an enormous amount of samples. According to DIN 19698, at least 9 laboratory samples should be taken for 500 m³: Each of these 9 samples is divided into 5 fractions according to grain size (F1 > 10 mm, F2 > 3 to 10 mm, F3 > 0.25 to 3 mm, F4 > 0.1 to 0.25 mm and F1 < 0.25 mm) and weighed. The coarser fractions F1 and F2 are then washed so that any particles containing asbestos are easier to detect. These are separated and their mass determined. The total mass of the asbestos-containing particles is the basis for the content determination.
Fibre structures are still extracted from the fractions F3 and F4, while F5 is prepared directly on the sample plate. If the "normal" VDI 3966 is sufficient for fractions F1 to F4, Appendix B is used for fraction F5. This makes it a bit bulky and quite expensive. From our original 9 samples for 500 m³ 45 samples become - under it 5 with extended preparation, whose costs lie over the normal analyses.
This method is therefore less suitable for routine monitoring of a limit value. Here, probably much more can be gained with good pollutant cadastres and pre-exploration.
The "end" for recycled building materials?
Furthermore, the question arises as to how many of the samples and their fractions may show a positive result until the entire material has to be declared as containing asbestos and thus as hazardous waste. Absolutely asbestos-free construction waste will probably not (yet) exist, at least not very frequently. The vast majority of the masses resulting from such measures are likely to contain one or the other asbestos occurrence. Just think of the many concealed asbestos products, which usually cannot be easily located or separated. In addition, some components containing asbestos often cannot be detected before demolition, e.g. spacers containing asbestos from concrete construction.
In the interests of conserving resources and the existing landfill space, a practicable solution urgently needs to be found that both serves the precautionary principle and enables the use of recycled building materials. This also includes the fact that asbestos should best not get into the dumps in question at all. Even if this probably does not always work. The question remains as to where the overall strategy lies, also in view of the future Ordinance on the Asbestos Stockpile. The discussion should have been going on for quite some time.
Urban mining – scenarios for future building material flows
Construction waste as concrete aggregate
After talking about recycling from the perspective of pollutants, Hermann Keßler from the Federal Environment Agency turned his attention to buildings and infrastructure as an important source of raw materials. The significance may become clearer if you look at the dimensions: The residential and commercial building stock alone contains 10.1 billion tons of building materials. The figure for all buildings and infrastructure is approx. 51.7 billion tonnes.
Around 235 to 253 million tonnes of sand and gravel are mined in Germany every year for construction purposes. The extraction area is equivalent to a good 2240 football fields or 14 square kilometres. On the other hand, construction waste and road construction in 2014 is still small at 68.2 million tonnes. But at least 55.3 million tons of it were used as recycling material. Including stone and soil processing, RC materials accounted for a good 12.3% of demand in 2014.
Unfortunately, only a small part of this is returned to building construction as high-quality concrete aggregate, replacing natural gravel. This is set to change in the future. This would not only conserve our natural resources, but would also minimize the consumption of landscape by gravel pits, etc. By 2020, a quarter of the gravel requirement could be covered by RC material. Due to the expected demographic change, this proportion could even rise to 36 % by 2050.
Gypsum recycling
Every year, around 650,000 tons of gypsum are produced in the building rubble. The recycling rate to date is in the single-digit percentage range. Landfilling is probably comparatively inexpensive, as the few gypsum conditioners complain about too low an acceptance rate.
Consumption of gypsum plasterboard in Germany is around 2.1 million tonnes. Of the 650,000 tonnes of gypsum waste mentioned above, a good 510,000 tonnes would be recyclable. This would certainly be an important way of protecting the valuable natural resources in this area. At present, 40 % of the gypsum requirement is covered by natural gypsum mining and 60 % by flue gas desulphurisation. However, the latter gypsum source will be eliminated in the course of a more or less rapid phase-out of coal-fired power generation.
However, the potential pollutants and impurities in construction waste must not be neglected. In addition to the asbestos already mentioned, PCBs and vanadium are also used in brick recycling. There will certainly be a lot to do for the recyclers and analysis laboratories concerned in the future. The raw material potential of our buildings will presumably gain in importance in the coming years.
Work on polluted buildings and facilities
Peter Götzelmann and Klaus-Thomas Maxeiner from Götzelmann Consulting GmbH reported on their experiences with public tenders for buildings contaminated with harmful substances. The knowledge level of the tendering agencies can fluctuate considerably. However, this level of knowledge also has a considerable influence on the quality of the tenders.
Overall, this year's DCONex was once again an interesting event, even though we were far from being able to attend all the lectures. Anyone who deals with the subject of building pollutants, their exploration, analysis or renovation should include DCONex in their calendar. The next edition will take place on 22 and 23 January 2020.
