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Previous research [1] showed high chloride concentrations (2% / cement) on the outside surface of reinforced concrete structures in the mist zone of marine environments. However, the chloride penetration reaches low depths for the concrete class used. Observed data have raised suspicions as to the effect of moisture content on the diffusion of chlorides. A test method was developed to assess the changes in the chloride diffusion coefficient with changes in moisture content in cement paste. It was concluded that the saturation degree (SD) (percentage of moisture content in the cement paste in relation to maximum water absorption of the cement paste) has a large influence in the chloride diffusion properties of the hardened cement paste, and this factor must be taken into consideration when predicting the service life of a reinforced concrete structure.

RESUMOEste projeto tem como propósito de estudo a possibilidade do uso de fibra para os blocos de contenção às ondas marinhas, de modo a influenciar na sua resistência e durabilidade. Levando em consideração o sucesso da utilização da fibra de aço em esgotos sanitários -um ambiente altamente corrosivo -seu uso tornou-se o mais indicado para o ambiente marítimo em questão. Tendo ciência que o concreto pode ser atacado até mesmo sem estar em contato com a água do mar -o ar deste ambiente, por si só, possui sais nocivos à pasta de cimento -foi feito um estudo baseado em um ensaio de durabilidade com blocos (contendo cloreto na massa e sem adição do mesmo) expostos às intempéries e, dentro da mesma análise, ensaio de "molhagem e secagem" utilizando solução de NaCl-para ativar na penetração dos íons cloretos, de modo a verificar a condição da fibra de aço e suas resistências por dois anos de idade.Palavras-chave: ambiente marítimo, fibras de aço, resistência e durabilidade. ABSTRACTThe present article's main objective is to study the possibility of using steel fibers in concrete to be applied under the format of blocks for the containment of marine waves, searching to influence their mechanical resistance and lifetime. Based on the success of utilizing steel fibers in concrete applied in sewage, a very corrosive environment, these fibers were also considered to be applied in the marine environment. Concrete might be attacked even without direct contact with sea water because of the high amount of chlorine contained in salts diluted in air. A study was made based on lifetime tests for two years with concrete blocks either containing or not chlorine in its constitution. The concrete blocks were exposed to atmospheric condition and also to a wet-dry testing procedure in the presence of NaCl to enhance the penetration of chlorine ions in the samples.

Mercury intrusion porosimetry (MIP) has been widely used to evaluate the quality of concrete through the pore size distribution parameters. Two of these parameters are the critical pore diameter (D crit ) and the percentage of the most interconnected net of pores compared to the total volume of pores. Some researchers consider D crit as the diameter obtained from the inflexion point of the cumulative mercury intrusion curve while others consider D crit as the diameter obtained from the point of abrupt variation in the same curve. This study aims to analyze two groups of concretes of varying w/c ratios, one cast with pozzolanic cement and another with high initial strength cement, in order to determine which of these diameters feature a better correlation with the quality parameters of the concretes. The concrete quality parameters used for the evaluations were (1) the w/c ratios and (2) chloride diffusion coefficients measured at approximately 90 days. MIP cumulative distributions of the same concretes were also measured at about 90 days, and D crit values were determined (1) from the point of abrupt variation and alternatively, (2) from the inflexion point of each of these plots. It was found that D crit values measured from the point of abrupt variation were useful indicators of the quality of the concrete, but the D crit values based on the inflexion points were not. Hence, it is recommended that D crit and the percentage of the most interconnected volume of pores should be obtained considering the point of abrupt variation of the cumulative curve of pore size distribution.

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