Electrical response-based technique for estimation of degree of moisture saturation in cement concrete and mortar in drying and wetting cycle

摘要

Cement-based materials (CBM) being porous allow movement of moisture, which is the primary cause of most of the deterioration of civil infrastructure. The degree of saturation (DoS) of CBM controls its transport property and estimation of this parameter constitutes an active field of research. In this paper, concrete and mortar samples of various water to cement ratio (w/c) and dimensions of 75 mm x 75 mm x 300 mm are used, which are conditioned to different DoS by systematically drying the samples in stages from the fully saturated state and conversely by wetting the sample from a fully dry state to full saturation. Copper electrodes are embedded in the sample at regular intervals for multiple measurements along the sample length. Using the D-Lorentz signal input, the electrical voltage drop-based response of the CBM sample at various locations on the sample surface and under various DoS are measured at multiple excitation frequencies in the Radio Frequencies (RF) range. By considering the ratio between the real and imaginary parts of the output and input voltages at various electrode positions, an empirical linear relationship is developed for the measurement of the DoS, which is applicable for all mixes of concrete and the mortar, subjected to drying and wetting cycles. (C) 2020 Elsevier Ltd. All rights reserved.