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Assessment of the Presence of Chlorides in Mortar through the Silver Nitrate Colorimetric Spraying Method



Author(s)

Victor Correia de Oliveira Pereira and Eliana Cristina Barreto Monteiro

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DOI:10.17265/1934-7359/2015.06.005

This study aims to evaluate the presence of free chlorides by the silver nitrate colorimetric spraying method in mortars made with Portland cement CP II Z-32. In order to make an assessment beyond the qualitative analysis, a calculation of the contaminated areas by free chlorides was performed by measuring the regions using a computer image analysis software (IMAGEJ). The experimental part of the research involved samples of 5 cm × 10 cm of mortar and 0.1 M solution of silver nitrate in distilled water. The mortar samples were made with cement CP II Z-32 with the following concentrations of chloride incorporated into the mixing water: 0%, 0.4%, 0.6%, 0.8%, 1.0% and 2.0%, in relation to the mass of cement, totaling 108 samples. The average of percentage results from the contaminated area of the series of samples was respectively 0%, 14.9694%, 19.7444%, 46.0239%, 62.3311% and 96.0083% in relation to the total area, concluding that the method of silver nitrate spraying is applicable and that the white color indicates the presence of chloride ions and other possible aggressive salts to the structure or the concrete.

Silver nitrate, chloride ions, corrosion, colorimetric method.