In situ investigation of the strength of deteriorated concrete

Abstract

A necessary prerequisite for devising a restoration scheme for a deteriorating structure is the acquisition of relevant in situ data to be used for evaluating structural adequacy as well as defining the scope of the restoration work. The methodology for conducting a successful structural in situ investigation includes: strategic planning, preliminary visual inspection, loading assessment, material property evaluation and load testing techniques. The single most sought after material property used for the evaluation of residual load capacity and structural adequacy of deteriorated concrete structures is the in situ concrete strength. The most direct method of obtaining this data is to test core specimens retrieved from the structure. It is not, however, always feasible to core for specimens and even if it is, the number of cores that can be taken is often limited. The solution is therefore to use indirect non-destructive and partially destructive techniques which measure concrete properties other than strength in combination with testing core specimens. Several of those techniques especially suited for in situ investigation are reviewed. Prior to using any of the indirect methods, a correlation needs to be established with the in situ concrete strength.