Graduate and Postdoctoral Research Symposium 2020 has ended
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Nima Hosseinzadeh Nanehkaran

Synergistic Effects of Air Content and Supplementary Cementitious Materials in Reducing Damage in Concrete Exposed to High Concentrations of CaCl2 and Freeze-Thaw Cycles
Poster Presenter #43
Ph.D. in Civil Engineering
Premature deterioration in concrete pavement joints often occurs within the first ten years of service and is both expensive and laborious to repair. The damage is attributed to a combination of conventional freeze-thaw damage and the formation of calcium oxychloride from a reaction between concentrated calcium chloride (CaCl2) solutions and calcium hydroxide in the concrete. Little research has been performed on the damage to concrete exposed to both freeze-thaw and concentrated CaCl2 solutions. In addition, it is known that air and supplementary cementitious materials (SCMs) reduce damage, though their interactions are not clearly understood. In this study, the synergistic roles of air and SCMs in reducing concrete damage under such conditions is studied. Cement pastes and their corresponding concrete samples were made with different SCM replacement levels; concretes were made with air contents ranging from 1.8 to 8.0%. Thermogravimetric Analysis (TGA) was performed on the cement pastes and concretes were tested using non-destructive tests such as mass (density), bulk resistivity, surface resistivity, ultrasonic pulse velocity and compressive strength as a destructive test. At 28 days, the cylinders were immersed in 25% CaCl2 solutions and subject to freeze-thaw cycles (-8 °C to 25 °C); non-destructive testing was carried out on the concretes after every ten cycles. Results suggest that bulk resistivity and surface resistivity are able to predict the performance of concretes exposed to these severe conditions. The roles of air and different SCMs in reducing damage can be separated and compared.

Additional author(s): Prannoy Suraneni