New method for continuous monitoring of concrete E-modulus since casting

Abstract

A new methodology that allows the continuous measurement of concrete E- modulus since casting is presented in this paper. This methodology is a variant to the classical resonant frequency methods, which have the downside of requiring concrete to be de-mouldable and withstand mechanical impact to start testing. The proposed experimental setup comprises a simply supported beam made-up with an acrylic tube, filled with the concrete to be tested, whose mid-span vertical accelerations induced just by ambient vibrations are continuously monitored by an accelerometer. The numerical treatment of the monitored accelerations allows identification of the 1st resonant frequency of the composite beam, which is evolving as concrete hardens. The E-modulus of concrete can thus be directly obtained from the monitored frequency. Besides the description of the overall setup, the results obtained in an experiment in which the concrete E-modulus was quantified also through static tests on the beam and via compressive tests in cylinders are presented and discussed. (c) 2010 Taylor & Francis Group, London.