Computed tomography as measurement method for condition assessment of asbestos-cement - Executive Summary - Degradation of asbestos-cement pipes shown perfectly with CT scans

Computed tomography (CT) can provide a very precise picture of the degradation of asbestos-cement (AC) pipes. Comparisons with the established georadar and thymolphthalein techniques show that CT closely matches thymolphthalein, while georadar systematically underestimates the deterioration of AC pipes. CT will be valuable as a reference for the validation of other techniques, and can be used for condition assessment whenever additional assurance and detail are desired.
Interest: prioritising AC pipe replacement Roughly 25% of the drinking water transport and distribution network is still made of asbestos-cement (AC). Drinking water utilities aim to replace AC pipes over the next decades. In order to replace the worst pipes first, the utilities need good methods to determine the condition of AC. A new method, computed tomography (CT), offers possibilities.
Approach: CT images converted into numbers; comparison with thymolphthalein and georadar With simple image processing steps, the CT scans of removed AC pipes are converted into numbers that can be used for further analysis. A study is then done to determine whether the degradation of the scanned pipes can be statistically described. Lastly, the technique is compared with two established condition tests: thymolphthalein and georadar.
Report: This research is described in the report Röntgentomografie als meetmethode voor toestandsbepaling van asbestcementleidingen (BTO-2019.010).