[show abstract][hide abstract] ABSTRACT: Most concrete and reinforced concrete buildings date back to the first half of the last century. Concrete proved to be a durable construction material in the recent years. However, reinforced concrete structures often experience degradation after years of service. Steadily tightening requirements for the building structure reliability give rise to the need for new diagnostic methods being capable of revealing building structure failures being about to occur soon, so that defective parts, if any, can be repaired or replaced in time. Destructive diagnostic methods have been developed during the recent years. Unfortunately, application of these methods impairs the structure integrity. Therefore, increasing attention is being paid to the development of non-destructive testing methods, among which acoustic methods are ranking as the most promising ones. These methods are mostly used for the defectoscopy of homogeneous materials and simple-shaped bodies. They have however not been elaborated enough to cope with diagnosing highly inhomogeneous materials, which is just the case of concrete. Our research focuses on studying potential applications of the acoustic emission method to testing the concrete and reinforced concrete elements and structures. A problem has arisen during our measurements of reinforced concrete elements, namely, how to distinguish the acoustic emission signal variations, which are due to steel armature corrosion, from those brought about by concrete composition changes, processing technology or material degradation induced defects. Therefore, in direct connection with the research of reinforced concrete structures, the effect of the plain concrete specimen structure on the acoustic emission signal variations has been studied.
[show abstract][hide abstract] ABSTRACT: Stability of building structures is one of very important issues in the field of non- destructive defectoscopy. Taking into account the fact that most of concrete and reinforced concrete structures were created in the first half of last century, it is evident that a search for new and simple defectoscopic methods, allowing the researchers to determine the integrity of these building structures or their parts, is of primary importance. It is also essential to develop and/or refine the methods designed to estimate the lifetime of building structures. The current methods of non- destructive testing of building materials are suitable for the defectoscopy of homogeneous materials and simple-shaped bodies. Their application to inhomogeneous building materials is difficult in the case of small-sized cracks and defects uniformly distributed throughout the specimen. This is why non-destructive diagnostic methods (NDT) are acquiring growing importance, helping the researchers to evaluate properly the condition of a bridge and decide upon the most convenient method maintenance, repair or refurbishment of the bridge in question or its parts and schedule them accordingly. Reconstructions of motorway bridges are frequently accompanied with long-time restrictions of the number of motorway lanes, which result in considerable delays and consequent financial losses of the motorway users. If the application of NDT methods contribute to optimizing the bridge repair interventions and their scheduling in conformity with safety rules, then the costs of researching new NDT methods are fully justified. One of the methods, which is recognized worldwide as the most promising for the mentioned purposes, is the acoustic emission (AE) method. By contrast to most other NDT methods, AE is a comprehensible method, allowing both one-shot examination and long-term monitoring of the condition of the structure under consideration or its selected parts. The present paper deals with the use of the AE method from the viewpoint of its application to diagnosing the bridge structure reinforcement corrosion and its consequences.