ABSTRACT
In the case of old concrete bridges in use, the compressive strength must be evaluated using a non-destructive test or a destructive test for only a small number of cores due to spatial and temporal constraints. Specifically, the compressive strength of the concrete for such structures is identified based on limited test data. Determining the overall compressive strength of structures by using a few measurements of compressive strength is challenging because the compressive strength of an old concrete structure is likely to indicate different degrees of damage or deterioration according to the position of the structure. This study performed a destructive test for 420 cores, which is challenging to perform on bridges in use to identify the statistical characteristics of the compressive strength of old concrete. These statistical characteristics were then analyzed in comparison with those of standard curing specimens 28 days old. The compressive strengths of the cores collected from the old concrete bridges were 82% – 200% of the specified compressive strength, indicating significant differences among the bridges. The variances of the measured compressive strengths of the cores collected from the old concrete bridges were 0.104 – 0.378. These results exceeded 0.058 – 0.061, which was obtained from the standard curing 28-day old specimens.
