TY - JOUR
T1 - Mechanism for salt scaling of a cementitious surface
AU - Valenza, John J.
AU - Scherer, George W.
N1 - Funding Information:
The authors are indebted to Dr Robert Flatt (Sika Technology, A.G.) for helpful discussions of this subject, particularly regarding the role of air entrainment. This work was supported by National Science Foundation Grant CMS-0200440.
PY - 2007/4
Y1 - 2007/4
N2 - Freezing and thawing of concrete in the presence of deicer salts results in superficial damage known as salt scaling. Scaling damage consists of the removal of small flakes from the surface, leaving the body susceptible to water and ion ingress, thus posing a significant threat to the durability of the body. None of the proposed mechanisms for salt scaling account for all of the phenomenology observed during previous studies. We report a novel experimental method designed to measure the stress that arises when a solution is frozen on a cementitious plate. These experiments reveal a thermal expansion mismatch (or, bimaterial) mechanism that accounts for all of the observed salt scaling phenomenology. According to the bimaterial mechanism, scaling occurs when the stress in the freezing layer rises above the tensile strength of the brine-containing ice, resulting in cracking. A viscoelastic analysis of the stresses in the brine/ice layer shows that pure ice would not crack, but a layer containing >1% NaCl would. The damage from cracking of the ice is exacerbated by weakening of the cement paste by exposure to concentrated brine.
AB - Freezing and thawing of concrete in the presence of deicer salts results in superficial damage known as salt scaling. Scaling damage consists of the removal of small flakes from the surface, leaving the body susceptible to water and ion ingress, thus posing a significant threat to the durability of the body. None of the proposed mechanisms for salt scaling account for all of the phenomenology observed during previous studies. We report a novel experimental method designed to measure the stress that arises when a solution is frozen on a cementitious plate. These experiments reveal a thermal expansion mismatch (or, bimaterial) mechanism that accounts for all of the observed salt scaling phenomenology. According to the bimaterial mechanism, scaling occurs when the stress in the freezing layer rises above the tensile strength of the brine-containing ice, resulting in cracking. A viscoelastic analysis of the stresses in the brine/ice layer shows that pure ice would not crack, but a layer containing >1% NaCl would. The damage from cracking of the ice is exacerbated by weakening of the cement paste by exposure to concentrated brine.
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U2 - 10.1617/s11527-006-9104-1
DO - 10.1617/s11527-006-9104-1
M3 - Article
AN - SCOPUS:34548292969
SN - 1359-5997
VL - 40
SP - 259
EP - 268
JO - Materials and Structures/Materiaux et Constructions
JF - Materials and Structures/Materiaux et Constructions
IS - 3
ER -