Assessment of in situ Characteristic Concrete Strength

When the seismic assessment of existing RC structures is conduct, a fundamental aspects is the assessment of in situ concrete strength; in fact, the compressive strength assessment of concrete in existing buildings is conditioned by various factors which are difficult to quantify especially when dealing with poor quality concrete. In this paper a series of destructive laboratory tests on 359 cores, extracted from specimens realized ad hoc at the Laboratory for Materials and Structures of the Mediterranean University of Reggio Calabria and from nine existing structures (buildings, viaducts, bridges and tunnels) were performed with the purpose to estimating the characteristic strength of in situ concrete. Moreover, an analytical expression was proposed in order to estimate the in situ characteristic concrete compressive strength. The results of these applications were compared with those obtained by other equations available in technical literature showing that the proposed formulation is capable of provided a good estimate of the in situ characteristic concrete compressive strength.