Monitoring of soil water content using spherical smart aggregates based on electromechanical impedance (EMI) technique

Abstract

Real-time monitoring of soil water content is of great significance to prevent many engineering accidents, such as landslide, water seepage of foundation dam and reduction of foundation bearing capacity. Smart aggregates (SAs) based on electromechanical impedance (EMI) technique have showed the excellent monitoring capability in various engineering applications, however, there are limited reports on the application in the monitoring of the soil water content. In this paper, the spherical smart aggregates (SSAs) based on the EMI technique were investigated in the monitoring of soil water content. Firstly, the SSAs were designed and fabricated by using the monolithic concrete encapsulation method, and their stable performance in air were evaluated and confirmed by testing and analyzing the impedance spectrum. Then, the fabricated SSAs were immersed into the water environment lasting for 28 days to ensure the stability under working conditions, such as the soil with high water content and the hydration process of early-age concrete. Finally, the monitoring experiments of soil water content were carried out based on the SSAs and the traditional SAs using the EMI method. The measured impedance signatures under different water contents in soil were quantified by three types of statistical indexes, including root mean square deviation (RMSD), mean absolute percentage deviation (MAPD), and correlation coefficient deviation (CCD). The experimental results show that compared to the traditional SAs, the SSAs are more sensitive and stable to monitor the soil water content.

Monitoring of crack repair in concrete using spherical smart aggregates based on electromechanical impedance (EMI) technique

“…To ensure the rationality of the results, the multiple specimens for the same experiment are tested, and the obtained results are consistent, which showed that the experiment is reliable. In addition, the earlier works have proved that the SSAs are more sensitive than the SAs in monitoring concrete hydration in very early age [53], soil water content [56], and damage of three-dimensional concrete structures [49], which indirectly indicate that the present results are reasonable. To further confirm the reliability of the present work, the numerical simulation based on the ANSYS software are conducted in this section.…”

“…In this section, the preparation process of concrete specimens will be described in detail. The SSAs fabricated using the monolithic concrete encapsulation method [56] and the traditional SAs [73,74] are adopted. The photographs of physical prototypes of SAs and SSAs used are shown in figure 2.…”

“…The SSA was first prepared by Kong et al [50,51] and the study on the vibration characteristics of SSA had been implemented by Wang et al [52]. So far, the SSA has been applied in quantitative damage evaluation of concrete [49], concrete hydration monitoring in very early age [53], evaluation of fiber content inside steel-fiber concrete (SFC) [54], hydration monitoring of steel fiber-reinforced cementbased material in very early age [55], and soil moisture content surveying [56]. However, to date, studies on the application of SSAs for monitoring the concrete crack repair process have not been reported.…”

Monitoring of the curing process and thermal failure of adhesive-bonded structures based on damping measurement using quantitative electromechanical impedance

“…Khan et al conducted numerical and experimental studies using EMI methods to predict the performance changes of concrete materials in real-time [28]. Lan et al employed EMI spectroscopy to monitor soil water content, which provides real-time information on moisture changes in the soil [29].…”