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Chloride ingress profiles measured by electron probe micro analysis
Traditional techniques for measuring chloride ingress profiles do not apply well to high performance cement paste systems; the geometric resolution of the traditional measuring techniques is too low. In this paper measurements by EPMA (Electron Probe Micro Analysis) are presented. EPMA is demonstated to determine chloride ingress in cement paste on a micrometer scale. Potential chloride ingress routes such as cracks or the paste-aggregate interface may also be characterized by EPMA. Chloride profiles are given for three cement pastes which have hardened for 1 month followed by exposure to a 3 % NaCl solution for a further month. Two exposure temperatures have been used: 5 deg C and 40 deg C. For the cement paste at w/c = 0.7 the chloride penetration has reached the center of the sample, 25 mm from the surface. The capillary pore structure in such a cement paste is continuous and the chloride ingress may solely be controlled by the transport process. The chloride has only penetrated the first one mm of a high performance cement paste with w/c=0.3 and 20 % silica fume addition. The chloride profiles seem to be solely controlled by the connectivity of the pore structure. For the cement paste at a w/c=0.3 without silica fume it is suggested that the chloride penetration is controlled partly by the transport process and partly by the connectivity of the pore structure.
Chloride ingress profiles measured by electron probe micro analysis
Traditional techniques for measuring chloride ingress profiles do not apply well to high performance cement paste systems; the geometric resolution of the traditional measuring techniques is too low. In this paper measurements by EPMA (Electron Probe Micro Analysis) are presented. EPMA is demonstated to determine chloride ingress in cement paste on a micrometer scale. Potential chloride ingress routes such as cracks or the paste-aggregate interface may also be characterized by EPMA. Chloride profiles are given for three cement pastes which have hardened for 1 month followed by exposure to a 3 % NaCl solution for a further month. Two exposure temperatures have been used: 5 deg C and 40 deg C. For the cement paste at w/c = 0.7 the chloride penetration has reached the center of the sample, 25 mm from the surface. The capillary pore structure in such a cement paste is continuous and the chloride ingress may solely be controlled by the transport process. The chloride has only penetrated the first one mm of a high performance cement paste with w/c=0.3 and 20 % silica fume addition. The chloride profiles seem to be solely controlled by the connectivity of the pore structure. For the cement paste at a w/c=0.3 without silica fume it is suggested that the chloride penetration is controlled partly by the transport process and partly by the connectivity of the pore structure.
Chloride ingress profiles measured by electron probe micro analysis
Bestimmung der Konzentrationsprofile von in Zementpasten eingedrungenem Chlorid mittels Elektronenstrahl-Mikrosonde
Jensen, O.M. (author) / Coats, A.M. (author) / Glasser, F.P. (author)
Cement and Concrete Research ; 26 ; 1695-1705
1996
11 Seiten, 7 Bilder, 4 Quellen
Article (Journal)
English
Chloride Ingress Profiles Measured by Electron Probe Micro Analysis
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