A new approach for the mix design of (patch) repair mortars

Abstract

The failure of most repairs in concrete structures is mainly manifested in the form of cracking and/or debonding of the repair layer. These two repair mechanisms could lead to the continuous corrosion of reinforcing steel in concrete. Cracking and debonding have been attributed to the high differential shrinkage that exists between the concrete substrate and repair layer as well as the lack of adherence, which commonly results from poor workmanship. It is crucial that restrained shrinkage mechanisms of patch repairs be understood so that the abovementioned effects can be prevented. The performance of patch repairs can be improved through the optimization of their mix design. Thus, it is common to use admixtures, non-cementitious compounds and polymers. However, promising technologies such as expansive admixtures that counteract shrinkage have found little application to date.