Delamination and spalling of concrete cover are common phenomena observed in structural concrete with severe
reinforcement corrosion. Repair of this damaged concrete may be carried out by patching method using appropriate
repair material. The material for patching application should be compatible with the concrete being
repaired. One of the compatibility issues being concerned is the fact that differential shrinkage exists between
repair material and parent concrete. This paper presents a method to evaluate shrinkage compatibility between
repair material and parent concrete. The development of the method was based on quantification of error coefficient
(M) of restrained shrinkage history occurred in repair material-concrete composite which induced tensile
stress. Restrained shrinkage history is a fraction of differential free-shrinkage between repair material and parent
concrete. Using value of M and estimated ultimate shrinkage, the magnitude of induced tensile stress can be
estimated. The magnitude of induced tensile stress may be compared with the tensile capacity of repair material
to determine if the material is compatible or not for patching damaged parent concrete. In the application of this
method, data of shrinkage observed on non-composite specimens and data of total deformation observed on
composite specimens are required. The method has been applied to evaluate the compatibility between repair
materials investigated in this research and concrete, with the conclusion is that all repair materials are
compatible.
Keywords: Coefficient of error, compatibility, repair material, shrinkage, tensile stress
