Verificação da tendência de penetração de cloretos em corpos de prova parcialmente imersos em água do mar Recife, PE

Abstract

Urban concrete or reinforced concrete structures built in saline environments, under either intermittent or continuous sea water exposure, usually present mechanical wear and structure pathology problems that require relentless maintenance care. Currently, Brazil has a large number of civil construction equipment and buildings under direct or near direct contact with the sea and the city of Recife, Pernambuco State capital, for one, figures among the top most exposed cities in terms of number of urban equipment in contact with sea water, including buildings, bridges, mooring sites, footbridges, piers, i.e., design projects that essentially imply concrete structures located under diverse marine exposure conditions such as underwater or partially submersed structures, or structures located in tidal zones or areas under mist or sea water splash environments. Sea water carries rather high chloride ion contents, hence making those exposed structures especially vulnerable. A chloride penetration study was carried out according to ISO TC 71/SC 1 (07/26/2010 release), ISO/WD 1920-11, ISO TC 71/SC 1/WG SII, and Brazilian ABNT NBR 12655 standards. Concrete core samples of several strength levels were kept partially submerged in sea water; chloride ion contents and penetration depths were recorded. Furthermore, a number of chemical analyses have been conducted in order to estimate chloride contents present at several depths in various concrete samples prepared with several W/C ratios, hence with different strength values. According to what one might expect, laboratory assays indicated that the deeper the axial sample taken from the exposed core for analysis and the more concentrated the concrete Water/Cement ratio, the lower the chloride penetration. Therefore, the chloride ion penetration rate indeed decreases as the W/C ratio gets richer, when compared to average and poor W/C ratios for all sampled penetration depths analyzed.