A novel early-age shrinkage measurement method based on non-contact electrical resistivity and FBG sensing techniques

As is well known, non-contact electric resistivity method is an effective measurement method for determining the hydration progress of cementitious materials. the hydration process is divided into four stages according to the electric resistivity measured by non-contact electric resistivity method. The evolution of shrinkage value in cement paste is mainly attributed to the chemical reaction and the hydration progress of cement. Fiber Bragg grating, as a novel sensor, has already been successfully used to measure the early age shrinkage in cement. In this paper, both FBG sensing and non-contact electric resistivity technique are employed to measure the shrinkage and electric resistivity, simultaneously. In this measurement system, the inherent advantage of electromagnetic immunity interference for FBG sensing is fully used. It can be concluded from the measurement results that the comprehensive system consisting of fiber optic sensing and non-contact electric resistivity technique is feasible and effective for investigating the early age properties of cementitious materials. The relationship between the hydration stages and the shrinkage variation law is preliminarily revealed.