Chemical indicator of carbonation of concrete
@ Import url (http://admin.archipassport.com/Load.ashx?type=style&file=SyntaxHighlighter.css) @ import url (http://www.archiproducts.com/styles/productssheetsections.css); @ import url (/ styles / editors / rteditor.css); A cement mix properly proportioned presents a strongly alkaline (pH13) that inhibits oxidation reactions of the reinforcement. The conglomerate, however, is permeable to which carbon dioxide can diffuse through it by reacting with substances that meets giving rise to the phenomenon of carbonation (environment pH9) and dimensional variations that lead to the cracking. The cracking promotes the penetration of the carbon dioxide is both water vapor which in turn triggers the oxidation process of the rebars. The measure of the depth of carbonation can be determined by spraying on the surface of the cement mix a solution of 1% phenolphthalein in ethanol. The test may be carried out directly on the structural element (removing, for example, the concrete cover in an edge) or on a cylindrical specimen extracted by coring element itself.
Normative reference: UNI 9944:1992: Corrosion and protection of concrete reinforcement. Determination of carbonation depth and profile of penetration of chloride ions in the concrete.