Protection of reinforced concrete and masonry distressed by carbamide from further destruction

Abstract

Corrosion of materials of masonry and reinforced concrete structures takes place in buildings in which production is associated with carbamide (material chemical formula CO(NH2)2). Carbamide dust accumulated on surface of structures with moisture makes carbamide solution of high concentration and penetrates easily into pores and capillaries of concrete or ceramics. Carbamide solution attacks concrete or ceramics and new combination in the form of strong and hard crystals is obtained. They increase in volume with time; their coefficient of temperature elongation is different from that of concrete. Increase in volume of the new combination, changes in ambient humidity and temperatures induce high internal stress due to strain restraint caused by carbamide crystals and destroy structure of concrete and ceramics. Results of special experimental investigations of specimens with various covers based on epoxy resins are presented. Analysis of these results showed, that the best cover is furfural cover, when concrete surface is mechanically cleaned and washed by water with special admixtures (water „X“).