Nondestructive Monitoring of Early Age Concrete

Improved performance of concrete structures requires better material processing techniques and early detection of defects. Poor service performance is often a result of improper material processing. Early development of damage in concrete structures is also related to insufficient strength development prior to loading the structure. An NDE technique that monitors the setting and hardening process of Portland cement concrete is presented in this paper. The technique is based on measuring the ultrasonic wave reflection factor (WRF) between the hardening concrete and a steel interface. This method can be used to assess the in situ properties of concrete at very early ages so that corrective measures can be taken. In addition, a nondestructive technique for determining the dynamic elastic material properties of concrete based on the vibrational resonance frequencies of finite length cylinders is presented. The accuracy of the proposed technique is verified through independent experiments on beam specimens.