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 thisway, six 40L tanks were made, covered with cement and sand mortar in 1:3, 1:4 and 1:5proportions. These tanks were supplied with bovine and swine wastes, diluted with water. Dataregarding waste degradation process were obtained by measuring variations of pH andoxidation-reduction potential in samples collected on the tanks before supplying, two monthsand four months after supplying. Data regarding mortars corrosion process were obtained on0.10 X 0.10 X 0.05 m test bodies, which were made with the same mortar proportions adoptedin the covering of the tanks. These test bodies stayed immersed in the referred wastes duringthe experimental period and, right after the exposure, they were analyzed. The results showedthat swine wastes provided larger difference of reduction-oxidation potential, what reinforces theneed of rigorous control of the corrosive process in structures exposed to those wastes. The pHvalue, in swine and bovine substrates varied between 6.9 and 7.6, what favored thedevelopment 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 thetanks used to storage swine and bovine wastes.