Non-destructive testing techniques - short NDT - are a vital part of surveillance of nearly all industrial sectors. NDT-methods are widely used to detect failures in certain components before and during their time of the operation. The goal is to find these failures before they affect the useability of the component..

Non-destructive testing techniques in civil engineering help to find out the state of a building with respect to

• building physics,
• environmental protection,
• analysis of building damages,
• building maintenance and
• construction inspection.

During the whole life-time of a concrete structure the reinforcement of the structure has to be protected by a sufficient concrete coverage against the penetrating carbonation front and the resulting loss of passivation. The adherence of the planned concrete coverage is nowadays part of quality assurance of the construction process. The concrete coverage of existing, older structures is often unknown. By means of reinforcement detection including measurement of the existing concrete coverage possible weak areas are securely detected.

In order to evaluate the actual state of bridges a number of inspections according to the german guideline DIN 1076 are performed regularly. It is the aim of these activities to detect damages early. Normally these activities consist only of visual inspections which provide an experienced engineer in almost all cases sufficient informations about the condition of the structure. Visual features may often give valueable information about the inner structure condition. If there are doubts adapted non-destructive or nearly non-destructive methods may be applied. By means of the application of such methods no or small local destructions are introduced to the structure under test. The latter ones may easily be repaired after the performance of the tests. Nevertheless these areas are weak-points of the structure. Hence non-destructive methods should always be preferred.

Secondary barriers made of concrete protect the environment against water polluting liquids if a leak arises in the first barrier. The capableness of these structures have to be proved periodically. Almost all secondary barriers are only accessible from the side which is impinged by the liquid in case of a first barrier damage. If cracks are present it has to be clarified whether these cracks affect the tightness of the barrier. Taking drill cores and refilling the holes leads to weak points of the structure. In addition the crack has to be stabilized with synthetic resin before drilling - a costly and time consuming technique which allows the assessment of the crack at certain points. To remedy the deficiencies of taking drill cores ultrasonic tests may be applied. In almost all cases the number of necessary drill cores are reduced dramatically. It should also be noted that the application of ultrasonic tests allows the assessment of a large number of points so a crack may be examined over its whole length.

Beside of the recognition of thermal energy loss in buildings thermography may also be used to gain other valuable information i. e. identification of hidden objects (plastered timber framework, concrete or steel piles), detection of voids or determine the water entry point in a flat roof. The method needs a temperature gradient and thus a flow of heat in the construction under test. This temperature gradient may often be generated by the fluctuation of temperature over day-time. The advantage of the inspection of large areas is accompanied by the disadvantage of the weather dependency resulting in difficulties in schedule definition.

The German federal agency for road construction (BAST) issued on 5th march 2002 the Guideline for Non-Destructive Testing of Tunnel Linings in the newsletter of the ministry of transport. This guideline is valid for all trunk roads owned by the federal government. Since the invention of this guideline Betontest is engaged in that field. Please read our page RI-ZFP-TU.

Betontest Ingenieurdienstleistungen supports its customers in the fields of non-destructive testing of buildings, concrete and concrete structures. Betontest acts as a consultant without favoring a certain test method. According to your task Betontest determines an optimized assessment and test concept. Betontest offers coordination and project lead services. Betontest may perform the assessment of buildings, concrete and concrete structures utilizing ultrasonic techniques, the localisation of reinforcement including the determination of concrete coverage and the proof of static capabinities by means of load tests. If further techniques have to be applied Betontest offers a wide range of services beginning with the invitations of tenders to the preparation of a final report.