Deterioration of Bond Integrity between Repair Material and Concrete due to Thermal and Mechanical Incompatibilities

The slant shear test highlighted by British Standard 6319 No. 4 was used to evaluate the bond strength between selected repair materials and parent concrete. Seven resinous and six cementitious repair materials were used to repair fractured specimens. Repaired test specimens were aged by subjecting them to heat-cool cycles that simulated repeated extreme summer day in the southern part of the United States (e.g., Mississippi). The results of thermal cycling showed a strong correlation between the difference in the coefficient of thermal expansions, as well as the difference in elastic moduli, between repair materials and concrete, and the reduction in bond strength. Although resinous materials possessed a higher bond strength to concrete, they showed higher reduction of bond strength than cementitious materials.