ON-SITE EARLY-AGE MONITORING OF HIGH-PERFORMANCE CONCRETE COLUMNS

The results of on-site temperature and strain monitoring of columns ma de with high-performance concrete at an early age are reported Two pai rs of circular 850-mm-diameter reinforced concrete columns made of 80 MPa concrete were instrumented with the aid of vibrating wire extensom eters. One of these columns was active because it was part of the stru cture of the new library of Concordia University in Montreal. The othe r one was never loaded and was used as a mock column. The strains in t he concrete and in the embedded steel, along with the internal tempera tures as well as the ambient temperature and relative humidity, were r ecorded The results of the experimental data show that the concrete is subjected to strains and stresses during the first 3 days due to ther mal gradient and different thermal behavior of concrete and steel. It was found also that the coefficient of thermal expansion of early-age concrete is substantially higher than that of hardened concrete.