Linking health monitoring in concrete structures with durability performance simulations

Service-life prediction models provide a useful and practical approach to estimate the durability that may be expected in concrete structures. For reliable performance predictions, these life-cycle models require accurate material property inputs that describe the quality of the placed concrete. Insitu sensing and monitoring has been suggested as an effective way to measure the properties of the in-place concrete. In this regard, the use of different types of sensors that measure fundamentally different material responses (e.g., stress/strain, acoustic/ultrasonic, electrical, and temperature) can be useful. This paper focuses on utilizing electrical conductivity measurements. It is discussed that while the sole measurement of concrete conductivity might not be able to accurately quantify material properties, a combination of three conductivity-based sensors plus a temperature measurement can provide valuable information for durability performance predictions. The proposed sensing system enables insitu measurement of properties such as porosity, pore connectivity, water permeability, and ion diffusivity. In addition, the sensors provide a means for life-cycle monitoring of moisture movement and ion (e.g., chloride) penetration inside the material. This paper discusses the applications of the sensing system and describes the role of each sensor, parameters measured, and principles of how each sensor operates.