Concrete, used in the production of highways and pavements, may deteriorate after many years of service, due to severe exposure conditions. Due to strategic and economic importance of such infrastructures, swift action for repair works is required. Repairs with conventional concrete may take long time for gaining adequate strength, where rapid strength gaining concrete often presents workability loss problems during application. In this study, a high performance concrete for repair of highways and pavements is developed. Laboratory and field tests are performed to assess workability, slump life and rheological stability. Early age properties are monitored by measuring the development of mechanical strength, fracture energy, hydration heat, thermal expansion coefficient and drying shrinkage. Durability properties, related to exposure conditions, are tested by permeability and salt scaling tests. During the development of the mix design of the high performance repair concrete, an admixture system, compatible with the cement and aggregates, is proposed. The 4-component admixture system consists of a superplasticizer to assure low water-to-cement ratio, synthetic crystals for achieving faster strength gain, microfibers to enhance early age cracking resistance and an air-entrainer to increase freeze-thaw resistance. The applicability of the proposed design was tested by full scale trial castings on site. Void system, internal stability and homogeneity of in-situ concrete was observed by microstructural examinations.
