Selecting Durable Repair Materials: Performance Criteria—Summary

Abstract

To achieve durable repairs, it is necessary to consider the factors affecting the design and selection of repair systems as parts of a composite system. Compatibility between repair material and existing substrate is one of the most critical components in the repair system. This article reports on a multi-phase research program that was initiated to develop performance criteria for the selection and specification of dimensionally compatible cement-based repair materials that will provide durable, crack-free nonstructural repairs. In the first phase of the study, preliminary performance criteria for dimensionally compatible repair materials were developed based on a review of the literature. This review concentrated on identifying pertinent material properties, appropriate test methods and demonstrated field performance. The second phase of the study included concurrent laboratory and field investigations to evaluate the preliminary peformance criteria. Results of the laboratory and field investigations were correlated in an attempt to conclude how individual material properties (strength, modulus of elasticity, thermal expansion, unrestrained shrinkage, restrained shrinkage, and creep) affect the potential for cracking of field repairs. While there was a general lack of significant correlation between individual material proprieties and field performance, these studies indicate that it is possible to predict the field performance of repair materials based on a combination of material properties determined in laboratory tests. A standard protocol for repair material datasheets as well as performance criteria for evaluation of alternative materials and specification of those materials with optimum properties are proposed.