Recent Progress in Smart Aggregate-Based Structural Health Monitoring of Civil Structures

This paper reports the recent progress in multi-functional piezoceramic-based smart aggregates research and their innovative applications in concrete civil structures. The basic operating principle of smart aggregates is first briefly introduced. The proposed multi-functional smart aggregate is formed by embedding a water-proof piezoelectric patch with lead wires into a small concrete block. The proposed smart aggregates are multi-functional and can perform three major tasks: early-age concrete strength monitoring, impact detection, and structural health monitoring. The early-age concrete strength development is monitored by monitoring the harmonic responses of smart aggregate. Impact on the concrete structure was detected by observing the open circuit voltage of the piezoceramic patch in the smart aggregate. For structural health monitoring purpose, an active-sensing sensor network is formed by embedding the smart aggregate and wavelet packet analysis is used as a signal processing tool. To verify the effectiveness and multi-functionality of smart aggregate, following research projects are performed: 1. Health monitoring of concrete columns under reversed cyclic loading; 2. Health monitoring of concrete columns under shake table excitation; 3. Wireless health monitoring of a two story concrete frame; 4. Wireless early-age concrete strength monitoring; 5. Impact detection for concrete piles; and 6. Health monitoring for concrete piles. The reported research activities were conducted collaboratively at three different institutes. The project of health monitoring under reversed cyclic loading test is performed at Missouri University of Science and Technology at Rolla, Missouri. The project of health monitoring under shake table excitation is performed at University of Nevada at Reno, Nevada. The projects of wireless health monitoring, wireless early-age concrete strength monitoring, impact detection and health monitoring for concrete piles are performed at the University of Houston. The multi-functional smart aggregates have the potential to be applied to the comprehensive monitoring of concrete structures from their early stages throughout their life-time.