Accelerated biogenic sulfuric-acid corrosion test for evaluating the performance of calcium aluminate-based concrete in sewage applications.
The corrosion of concrete structures in sewage environments is a major problem in some areas. The phenomena leading to formation and stripping of H2S are now reasonably well understood. By a biol.-influenced process, the metab. of thiobacilli, hydrogen sulfide is converted into sulfuric acid. This acid reacts with concrete and causes deterioration. For the purpose of testing materials, this environment is often simulated by lab. tests with concd. acid solns. Such tests, however, do not consider the bacterial aspect of the reality, and therefore, can lead to irrelevant conclusions. For a reliable result, the interactions between living organisms and their substratum are essential and need to be taken into account. This task is achieved by the use of our simulation chamber for biogenic sulfuric-acid corrosion. The biol.-influenced corrosion is remodeled under conditions favoring the relevant microorganisms. Thus, an acceleration of the natural process is achieved. Recent investigations conducted on calcium aluminate-based mortars in the bacterial-corrosion chamber of Hamburg University demonstrated for these materials a good resistance against biogenic sulfuric-acid attack. These results are confirmed by on-site observations of sewer pipelines made of calcium aluminate-based concrete inspected after up to 35 yr of service in harsh environments.
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