A study of NDE-performance in the condition assessment of reinforced concrete structures

In order to understand the condition of concrete structures with a view to effective maintenance planning then inspections should be customised to meet individual needs. If inspections are to provide more than superficial information then non-destructive testing methods will be required. The recent interest in non-destructive testing has been considerable, yet it's application limited. The methods are considered to be mainly qualitative, and they are sometimes regarded as being ambiguous as well as not capable of performing sufficiently well in real situations. The demands placed on non-destructive testing method capability are usually expressed in simple terms, such as the ability to detect a defined size of void. There has been little done to express the inspection needs in terms of typical problem cases, with a clear definition of defect type, acceptance criteria and limiting conditions. In turn there are few accepted procedures for applying non-destructive testing, as there are few examples of typical cases. Emphasis should perhaps be placed on focussing the available technology on well-defined problem cases and dealing with these from an engineering viewpoint. Recent work with High Energy Radiography combined with a digital imaging system is presented here together with a new ultrasonic pulse echo technique. Both of these have meant considerable advances in NDT-techniques and are presented briefly in this paper.