Title: Durability of Repairs under Freezing and Thawing and Alkali-Aggregate Reaction
Author(s): Keikhosrow Tahmureszadeh, Medhat H. Shehata, and Bill Gong
Publication: Materials Journal
Appears on pages(s): 197-208
Keywords: alkali-aggregate reaction; bond strength; concrete repairs; deicing salt; dimensional compatibility; durability; effect of surface roughness; freezing and thawing; shrinkage
The durability of three repair materials was investigated under two exposures: freezing-and-thawing cycles in the presence of deicing salts, and substrate undergoing expansion due to alkali-aggregate reaction (AAR). The bond strength of the repairs under freezing-and-thawing exposure was evaluated using slant shear, splitting tensile, and pulloff tests. Additionally, the pulloff test was implemented to investigate the bond strength of repairs undergoing
expansion due to AAR. Under freezing and thawing, the substrate surface roughness was evaluated and resulted in a higher bond strength under combined shear and compression forces (slant shear test). The results for both exposures showed that the efficacy of a repair could not only be explained based on the net unrestrained length change between the repair and the substrate. While significant autogenous shrinkage of ultra-high-performance concrete (UHPC) can increase the net unrestrained length change, the strength, fibers, and high paste content of such material enhance
the bond strength.