Accelerated testing of materials under the influence of biogenic sulphuric acid corrosion (BSA)

The number of damages caused by biogenic sulphuric acid corrosion (BSA) is increasing. BSA is a damage situation that often occurs in sewer systems, building drainage, wastewater treatment plants and biogas plants. Sulphuric acid, which is generated through microbiological conversion of sulphur, leads to a combined chemical-biological attack on the surfaces. The development of materials resistant to BSA requires testing methods that allow for a testing of materials that is both oriented towards practice and accelerated. More than 10 years ago at Fraunhofer UMSICHT a weathering test was set up. The weathering test provides an accelerated weathering of materials. Based on the results the optimization and further development of materials can be carried out. The test rig consists of different chambers that allow the testing of materials which consist of mortar, concrete, and polymers as well as coated systems. Focused on mortar and concrete details of the test are presented. Results regarding mass loss and pH of test samples as a function of weathering time are shown for three types of cementitious mortars. An approach to obtain corrosion rates based on the BSA carried out is presented.