title: Microstructural Origins of Cement Paste Degradation by External Sulfate Attack.
abstract: A microstructure model has been applied to simulate near-surface degradation of portland cement paste in contact with a sodium sulfate solution. This new model uses thermodynamic equilibrium calculations to guide both compositional and microstructure changes. It predicts localized deformation and the onset of damage by coupling the confined growth of new solids with linear thermoelastic finite element calculations of stress and strain fields. Constrained ettringite growth happens primarily at the expense of calcium monosulfoaluminate, carboaluminate and aluminum-rich hydrotalcite, if any, respectively. Expansion and damage can be mitigated chemically by increasing carbonate and magnesium concentrations or microstructurally by inducing a finer dispersion of monosulfate.
authors.affiliation: Southeast University, Nanjing, Jiangsu 210096, China ; National Institute of Standards and Technology, Gaithersburg, MD 20899, United States.
authors.forename: Pan
authors.initials: P
authors.lastname: Feng
authors.affiliation: National Institute of Standards and Technology, Gaithersburg, MD 20899, United States.
authors.forename: Edward J
authors.initials: EJ
authors.lastname: Garboczi
authors.affiliation: Southeast University, Nanjing, Jiangsu 210096, China ; Jiangsu Research Institute of Building Science Co., Ltd, Nanjing, Jiangsu 210008, China.
authors.forename: Changwen
authors.initials: C
authors.lastname: Miao
authors.affiliation: National Institute of Standards and Technology, Gaithersburg, MD 20899, United States.
authors.forename: Jeffrey W
authors.initials: JW
authors.lastname: Bullard
keywords: cement paste; computer modeling; degradation; expansion; microstructure; sulfate attack