Asbestos detection in buildings to prevent contamination of the recycling material stream

The BMBF-funded research project “RECBest” aims at developing reliable methods for the detection and removal of hazardous building materials before demolition and at enhancing the resulting recycling material (RCM) through specialised processes.This presentation discusses select findings of the first year of research focusing on the detection of asbestos in buildings.

In September of 2021 the VDI 6202-3 was published, giving a statistical approach to the exploration and assessment of asbestos in buildings. Therefore, five condemned buildings that had previously been inspected for asbestos not using the VDI 6202-3 were again examined according to the VDI 6202-3. Comparing the results of both approaches showed that the standardised VDI method led to more reliable and detailed results. However, the common limitation remains the surveyors conducting the inspection as they have to correctly identify possible asbestos-containing materials beforehand.

A common problem during the inspection of condemned buildings for asbestos are concealed materials such as rebar spacers made of asbestos concrete. Thus, a non-invasive method of detecting rebar spacers using radiography was tested on a block of reinforced concrete. The resulting two-dimensional pictures clearly showed the locations of the rebar within the concrete block. Although the rebar spacers themselves could not be observed, the wires used to hold the spacers in place were visible and can therefore indicate where core drilling samples should be obtained.