Effect of uneven porosity distribution in cement paste and mortar on reinforcing steel corrosion

Journal Article · Sat Jan 01 04:00:00 EST 1994 · Cement and Concrete Research; (United States)

DOI:https://doi.org/10.1016/0008-8846(94)90029-9· OSTI ID:6989043

Gu, P; Fu, Y; Xie, P ^[1]; Beaudoin, J J ^[2]

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1. Univ. of Ottawa, Ontario (Canada). Dept. of Civil Engineering
2. National Research Council, Ottawa, Ontario (Canada). Materials Lab.

The influence of heterogeneity of cementitious matrices, e.g. uneven porosity distribution in repair cement paste or mortar, on surface corrosion of the reinforcing steel was investigated using a low frequency impedance technique. Rebar embedded in lower porosity matrices had lower surface impedance and phase angle values in the frequency range 1Hz to 10mHz. The corrosion reactions appeared to preferentially occur on the surface of rebar embedded in denser matrices. This observation was valid in cases with and without admixed chloride ions. A possible explanation of the surface corrosion mechanism of reinforcing steel is given. The phenomenon is explained by the depletion of oxygen concentration at the steel-cement paste interface resulting in the formation of an anodic area.'' The chloride ions accelerate the corrosion reaction by destroying the iron oxide film and reducing the pH values at the steel-cement paste surface.

• OSTI ID: 6989043
• Journal Information: Cement and Concrete Research; (United States), Journal Name: Cement and Concrete Research; (United States) Vol. 24:6; ISSN 0008-8846; ISSN CCNRAI
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360105* -- Metals & Alloys-- Corrosion & Erosion
360606 -- Other Materials-- Physical Properties-- (1992-)
ALLOYS
BUILDING MATERIALS
CEMENTS
CHEMICAL REACTIONS
CHLORIDES
CHLORINE COMPOUNDS
COMPOSITE MATERIALS
CONCRETES
CORROSION
HALIDES
HALOGEN COMPOUNDS
IRON ALLOYS
IRON BASE ALLOYS
MATERIALS
MEASURING METHODS
MORTARS
POROSITY
REINFORCED CONCRETE
REINFORCED MATERIALS
STEELS