摘要: |
Concrete repair and rehabilitation will have an even more vital role in the future than it does now. Major reconstruction of our aging infrastructures can no longer be delayed. Critical to achieving long service life of repaired structures is the correct choice and use of materials. Evaluation of materials by research and testing falls far behind the development of new products. Regrettably, design professionals still do not fully understand such aspects of their medium as (a) the importance and meaning of compatibility between repair materials and existing substrate and (b) the considerable differences between the properties measured by existing standard methods and the properties of the same materials in situ. The designer and prospective user of materials are not equipped with performance criteria that provide a rational analytical tool for selecting the appropriate materials for a particular repair in a specific environment. Without such criteria, durable concrete repair is more of an art than a science. Compatibility, the most important factor determining the durability and structural effectiveness of concrete repairs, is defined and discussed; drying shrinkage, one of the decisive components of compatibility, is discussed in detail. A ranking system that would help in the selection of repair materials with a lower risk of shrinkage stresses, cracking, and debonding is proposed. In conclusion, there is an urgent need for development of performance criteria for the selection of compatible repair materials, along with the selection or development of a reliable industrywide shrinkage test method. |