CORES FROM HIGH-PERFORMANCE CONCRETE BEAMS

An experimental investigation involving 287 concrete core specimens ob tained from large beams cast from 45 to 90 MPa (6500 to 13,000 psi) or dinary portland cement concretes is described. The data indicate the e ffect of variations of core size and test moisture condition on the me asured compressive strength of cores from elements made of high-perfor mance concrete. The relationship between the flexural capacity of the beams and the strength of the cores obtained from the beams is investi gated. The data indicate that the least-biased estimate of the in situ concrete compressive strength if found by increasing the strength of sealed cores by 6 percent to account for damage sustained during drill ing of the core. However, a reasonable estimate of the in situ concret e compressive strength may be obtained by correcting the strengths fro m tests of air-dried or soaked cores to account for both core damage a nd moisture condition factors.