Assessing the mechanical behaviour of concrete before and during setting with a resonance based technique: preliminary prototypes and results

Abstract

This paper presents the preliminary studies towards a new methodology for the assessment of the mechanical behaviour of concrete before and during setting. The method is called ‘Stiffness Monitoring at very Early Age” (SMEA), and it consists in monitoring the first flexural resonant frequency of a steel plate that is partially embedded in the testing material, and partially salient towards the exterior. An accelerometer placed at the free extremity of the resulting cantilevered plate allows the use of operational modal identification techniques to assess the first flexural resonant frequency of the plate. The paper shows that this resonant frequency endures significant evolution at the very early ages (mainly before the setting of concrete), and comparisons are made to measurements taken in the same batch of concrete through: setting time through an ASTM C403 penetrometer; the existing EMM-ARM method for measurement of E-modulus of concrete; the propagation of P-waves in concrete since the fresh state.