Realkalisation of the Carbonated Concrete using Alkaline Solutions


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Title: Realkalisation of the Carbonated Concrete using Alkaline Solutions

Author(s): F.W.C. Araujo and E.J. Pazini Figueiredo

Publication: Special Publication

Volume: 229


Appears on pages(s): 19-32

Keywords: carbonation; concrete; corrosion; realkalisation

Date: 9/1/2005

Some protective techniques, such as anti-carbonation coating, provide the concrete a protection due to the creation of a surface barrier that prevents the penetration of CO2 and moisture. However, these procedures are not always so effective when the carbonation process moves as a front through the concrete pores, reaching the reinforcement. In this case, the procedure often adopted is the repair technique, which can include the anchorage of the structure, the entire removal of the carbonated layer and localized or general repair. The purpose of this research was to study the non-destructive repair technique referred as realkalisation by the absorption and diffusion of alkaline solutions. In order to provide evidence for further analyses of the technical viability, besides the main realkalisation testing, some additional tests such as compressive strength, capillary absorption, electrochemical techniques and mortar adherence on realkalised substrates, were performed. The results obtained show that realkalisation through direct contact of the alkaline solution on the concrete surface is effective in re-establishing the high pH of the concrete, although it presented a slight decrease in the compressive strength. The realkalisation process does not interfere in the mortar adherence to realkalised substrates.