Biological Corrosion of Polymer-modified Cement Bound Materials Exposed to Activated Sludge in Sewage Treatment Plants

This paper presents a study of 7 and 18 months exposure to activated sludge in a sewage treatment plant on its durability of Portland cement materials (CEM I) containing polymer modifications. The samples were tested for tightness and flexural strength after exposure to a sludge environment containing 108-109 microorganisms per ml, including filamentous heterotrophic bacteria, protozoa, rhizopoda, ciliates and fungi. The corrosion processes were identified by COD analysis, by aid of a scanning microscope with an X-ray microanalyzer and by mercury porosimetry.Studies have shown, that selecting the polymer admixture to of cement materials should be considered: the parameters rallying improvement (tightness, adhesion, chemical resistance), but also the conditions of use mainly susceptibility to biological corrosion of polymers.