Structural analysis of pathological and light towers from the beaches of Santos city

Abstract

The assault on the concrete for carbonatation andchloride ions in coastal areas can cause corrosion of the reinforcement, thisphenomenon requires special attention because in marine environments, the atmosphereis impregnated saline mainly by chloride ions. These ions are absorbed by thepores of the structure and subsequently diffuse toward the concretereinforcement. The corrosion rate of the reinforcement is accelerated in thecase of carbonated concrete and subjected to salt atmosphere. The carbonatedconcrete reduces the critical level of chloride required for corrosion tooccur, and when the armor is hit, the pole must be recovered or replaced. Thepredominant factor for carbonatation that there is the presence of carbon dioxide(CO2) in the air, since the mobility of the chloride ion structures in the sea,they are: distance from the structure in relation to the seafront, speed anddirection of winds, relative humidity, water / cement ratio used in thepreparation of concrete, household composition, percentage of tricalciumaluminate present in the cement paste and temperature. The objective was toevaluate the critical depth of carbonatation and chloride content in theconcrete pylons (towers) of waterfront in the city of Santos. Samples werecollected for determination of the depth of carbonatation and chloride contentin the laboratory. Finally, the results were compared with the levelsestablished by the deterioration of the CEB Bulletin 162 - Comite EuroInternational du Beton (1983), and the prescribed and acceptable in NBR 6118(2007), verifying that the posts need immediate interventions. It was observedthat carbonatation light varied inversely with the depth of the sample did notvary as a function of the position of the hole. The concentration of chlorinewas independent of the position and depth of the sample taking likely source ofthe towers in manufacturing, obtaining results below the maximum permitted byseveral authors (0.4% by weight of cement).Keywords: carbonatation, chloride, corrosion, condition of the concrete.