Specification of materials for concrete repair is a complex task requiring broad knowledge of materials science, engineering and construction practice. In this paper, several issues important for proper design and implementation of concrete repair are discussed. It is stressed that the specification documentation is not a formality, but rather a critically important engineering step in view of fulfilling the durability and service life requirements. Keywords: concrete repair, repair design, materials specification, compatibility factors. Streszczenie. Specyfikacja materiałów do napraw konstrukcji betonowych jest złożonymzadaniemwymagającymrozległejwiedzy z zakresu podstaw naukowych, inżynierskich oraz doświadczeń praktycznych.Wartykule przedyskutowanowiele zagadnień istotnych przy przygotowaniu projektu naprawy konstrukcji betonowej i jegowdrożeniu. Podkreślono, że specyfikacjamateriałówjest nie tylko formalnością, ale stanowi szczególnie istotne wytyczne inżynierskie pozwalające na spełnienie wymagań trwałości. Słowa kluczowe: naprawa betonu, projekt naprawy, specyfikacja materiałów, rodzaje kompatybilności.Good concrete repair is not a bandage "fix" (Photo) for a structure in trouble - rather, it is a complex system that consists of numerous engineering tasks (Fig. 1). Designing and specifying concrete repair has unique needs differing from new construction. Therefore, the specifications must serve as action plans or roadmaps for the project’s engineer, contractor, and quality controller. Unfortunately, when it comes to the durability of repaired concrete structures, project documentation is not always adequate. For example, one shortcoming constantly repeated in specifications is the frefrequent reference to the "direction" of the engineer or architect. The authors came across a specification concerning a material for an industrial plant repair project that simply read: "The patch repair material’s durab[...]

  The aim of concrete repairs is to extend the useful service life of an existing structure, to restore its load-carrying capacity and stiffness, and/or to strengthen itsmembers [3]. The requirement for compatibility between the existing concrete and the repairmaterial has been addressed conceptually by various authors since the early nineties [1 ÷ 6]. Guidance on the approach can now be found in reference documents such as EN 1504, ACI 562, and report MERL-2014-87 issued by USBR [8]. The level of compatibility will generally determine whether a repair project is a success or a failure, and whether a repaired structure is durable. One of the main challenges to be faced now lies in evaluating quantitatively compatibility and determining what it requires under given circumstances (characteristics of the structure to be repaired and the environment). For the compatibility approach to be fully implemented in repair engineering design, adequatee characterization tests and design tools for concrete repair are needed. In the present paper, two approaches for quantitative evaluation of dimensional compatibility of repairs are presented. Compatibility index evaluation based on the restrained- -shrinkage ring test Restrained-shrinkage ring test. This paper presents the results of the large project on the quantitative relationship between the individual dimensional compatibility-related properties (notably elastic properties, creep, drying shrinkage) and the corresponding stress and strain values recorded in an annular restrained shrinkage test, commonly referred to as the ring test (Figure 1). While the actual deformation and stress gradients across the thickness of the specimens are considered in the calculations, the analysis of the results is based on the average stresses. The evolution of the average shrinkage-induced stress (σc avg.) over time can be calculated with equation 1, where εfs is the concre[...]