Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
259483 | Construction and Building Materials | 2011 | 10 Pages |
Deterioration of concrete in cooling tower basins by microbiologically influenced corrosion (MIC) is a concern in geothermal power plants. The effect of supplementary cementitious materials, epoxy coatings, latex-modified mortars and calcium aluminate cement mortar for protecting concrete from MIC was investigated. Laboratory exposure tests to a particular type of sulphur and iron oxidising bacteria, Thiobacillus ferrooxidans, were performed to rank candidate materials and these were followed by field exposure tests of the best materials in a cooling tower basin. It was determined that partial replacement of cement with 40% blast furnace slag or 5% to 10% silica fume improved resistance to MIC. A replacement level of 60% slag resulted in similar performance to concrete made with ordinary Portland or sulphate resistant cement. Epoxy- and styrene butadiene latex-modified mortars offered protection to concrete but still underwent a degree of attack. Epoxy coatings were found to be effective in protecting concrete. Calcium aluminate cement mortar showed excellent durability in laboratory and field tests.
► Investigated means of protecting concrete against acid produced by sulphur oxidising bacteria in geothermal power plants. ► Studied influence of partial replacement of cement with silica fume or blast furnace slag in resistance to bacteria. ► Studied suitability of epoxy coatings, latex-modified mortars and calcium aluminate cement mortar for protecting concrete. ► Found that silica fume, epoxy coatings and calcium aluminate cement mortar offered best protection.