Comparison of evaluation tests for compressive strength of structural concrete

The concrete strength of existing structures is an important index in the aspects of safety insurance, evaluation, and strengthening of existing structures. However, different testing methods are used to evaluate the concrete strength, which provide information with different reliability, and the results are thus difficult to be unified. This paper investigated the evaluation tests for compressive strength of structural concrete. The compressive strength of field-cured, standard-cured and core samples, and the rebound method calculated strength of structural concrete were obtained. The results showed that the compressive strength of field-cured and core specimens, and the rebound method calculated strength cannot reach that of standard-cured specimens at the equivalent age of 28 days. The compressive strength of standard-cured and field-cured specimens can be used to represent that of cores for evaluating the quality of structural concrete. All four strength indexes increased in a logarithmic trend with the increasing equivalent age.