Mechanism for using piezoelectric sensor to monitor strength gain process of cementitious materials with the temperature effect

摘要

Recently, the piezoelectric based sensor coupled with electromechanical impedance (EMI) technique is gaining attention on monitoring the mechanical properties changes in cementitious materials. However, the EMI signals obtained from the sensing system are not only influenced by the development of inherent mechanical properties in the host structure but also affected by the variation of temperature. When implementing a piezoelectric based sensor, both the ambient temperature change and the heat release from newly casted concrete would influence the sensing accuracy. In order to eliminate the biases from temperature effect, the mechanisms of EMI technique for strength sensing were investigated. The experiment work was separated in two parts. The piezoelectric sensors were first used to monitor the strength gaining of the newly casted cementitious samples curing under constant temperature. A strength estimation system was developed based on the experiment results. Later, the temperature variation was induced to affect the sensing performance. A temperature compensation technique was proposed to eliminate the temperature effect. It has concluded that the proposed compensation method can improve the strength sensing accuracy. The new understanding should help to promote the practical applicable EMI sensing technique.