Geocement-based Coatings for Repair and Protection of Concrete Subjected to Exposure to Ammonium Sulfate

摘要

The geocement-based coatings for repair and protection of concrete structures of which the installations for production of biogas, water supply and sewage water disposal pipelines are made have been developed and have been tried in practice. Resistance of the developed coatings in an aggressive environment (5% solution of ammonium sulfate) as well as basic physico- chemical processes taking place during interaction of the ammonium salts with the geocements have been studied and the results are discussed. A conclusion was made that among other geocement hydration products which can resist attacks of sulfate-ammonium ions, faujasite, chabazite and mordenite had the highest resistance, whereas heulandite and hydrosodalite have the lowest resistance. This assumption is in agreement with the outcomes of other researchers. The results of examination show that the ammonium-containing zeolites have been synthesized within the hydration products, these were: ammonium analcime, (NH_4, Na)-zeolite-E, zeolite a, zeolite ZK-21 and NH_4-zeolite-W. The coated concrete (a geocement (Na_2O×Al_2O_3×6SiO_2×30 H_2O)-based coating)) is found to be corrosion resistant in aggressive environment containing ammonium sulfates: its coefficient of resistance is 1.01, being at an age of 30 days by 1.2 times higher compared to that of the uncoated concrete of the same age.