Publication Date


Date of Final Oral Examination (Defense)


Type of Culminating Activity


Degree Title

Master of Science in Civil Engineering


Civil Engineering

Major Advisor

Yang Lu, Ph.D.


Debakanta Mishra, Ph.D.


Lan Li, Ph.D.


Concrete structures experience damage due to Sulfate Attack (SA) and Freeze-Thaw (F-T) in cold regions containing ample amount of sulfate species. The combined effect of SA and F-T is a multiscale multiphysics damaging process for cementitious materials involving complicated chemical reactions and phase transition inside concrete pores. This thesis is a compilation of two theoretical models describing the SA induced damage in an unsaturated cementitious medium and damage due to the combined effect of SA and F-T. The classical theory of phase change and a diffusion-reaction process is utilized in the development of the models. The validity of the proposed models is tested by comparing the numerical results against existing experimental data for concrete mortars. It is found that the numerical results agree very well with the experimental results. These coupled mathematical models can be applied to assess the effect of ambient sulfate concentration on the degradation of concrete, the pore-size distribution (PSD), hysteresis of solidification and melting of water in concrete pores and change of porosity due to SA and F-T. Most importantly the proposed mathematical model is capable of explaining the damage extent of concrete under coupled conditions that are somewhat difficult and time consuming to be evaluated by contemporary experimental methods.