An embeddable spherical smart aggregate for monitoring concrete hydration in very early age based on electromechanical impedance method

Abstract

In this paper, a new embeddable spherical smart aggregate (SSA) was utilized to monitor concrete curing in very early age. Overcoming the limitation of the existing PZT-patch-based transducers, the SSA provides vital changing information in all directions of host structure. To verify the advantage of SSA in structural health monitoring (SHM), the sensitivities of SSA and smart aggregate (SA) in monitoring concrete cube deformation and stiffness variation were analyzed and compared by numerical simulation. The feasibility of SSA in monitoring the concrete hydration process was studied by experiments utilizing electromechanical impedance (EMI) technique. At last, four SSAs were embedded in a concrete column to study the practicality of SSA in monitoring the concrete curing process in very early age. The EMI signatures and the root mean square deviation (RMSD) values of the collected information from SSAs were analyzed. The results illustrate that the SSA is more sensitive than SA in monitoring the concrete deformation and stiffness variation. The data measured by SSA in monitoring the concrete hydration process fluctuates more obviously than the data recorded by SA. The new spherical transducer can effectively and reliably monitor the concrete hydration process.

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

“…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.…”

Modeling and electromechanical performance of improved smart aggregates using piezoelectric stacks

“…The TSA is more suitable for damage detection in 2D concrete structures [28], such as cement concrete pavements, floors, and shear walls. The third type is the embeddable spherical SA (SSA) [29][30][31][32][33], which was fabricated by bonding two hemispherical piezoelectric shells and two hemispherical UHPC cases using epoxy resin. The SSA has good ability in space omni-directional actuating and sensing functionalities.…”

Multidirectional crack monitoring of concrete structures using 3D piezoceramic sensing array

“…Because of the 3D shape of piezoceramic‐to‐UHPC shell, SSA could offer omni‐dimensional actuating and sensing capability that extremely expends the scope of applications for the current SA‐based sensing technology. Following the studies of SSA dynamic properties, 23 researchers have utilized SSA for early age cement hydration monitoring 24 and damage characterization of concrete cube specimen 25 . The extraordinary omni‐dimensional actuating and sensing capability of SSA exhibits great suitability for multidirectional crack monitoring in concrete structures (Figure 2) and gives it ability to simplify the current SA‐based sensor deployment.…”