Corrosion of mortar coverings used in structures of management exposed to swine and bovine wastes

The objective of this research was to analyze the corrosion process of mortars, usually used in the covering of storage tanks for residues produced in livestock housing. In this way, six 40L tanks were made, covered with cement and sand mortar in 1:3, 1:4 and 1:5 proportions. These tanks were supplied with bovine and swine wastes, diluted with water. Data regarding waste degradation process were obtained by measuring variations of pH and oxidation-reduction potential in samples collected on the tanks before supplying, two months and four months after supplying. Data regarding mortars corrosion process were obtained on 0.10 X 0.10 X 0.05 m test bodies, which were made with the same mortar proportions adopted in the covering of the tanks. These test bodies stayed immersed in the referred wastes during the experimental period and, right after the exposure, they were analyzed. The results showed that swine wastes provided larger difference of reduction-oxidation potential, what reinforces the need of rigorous control of the corrosive process in structures exposed to those wastes. The pH value, in swine and bovine substrates varied between 6.9 and 7.6, what favored the development of microorganisms that attacked the mortars. The 1:3 proportion mortar resulted smaller corrosion and roughness, being the most suitable for covering internal surfaces of the tanks used to storage swine and bovine wastes.