Nondestructive analysis techniques for freeze-thaw damage detection in concrete slabs using shear waves

Freeze-thaw damage in concrete structures is a serious issue for infrastructure in cold regions. Accurate detection of this type of damage at early stages allows for the selection of optimum strategies for preservation and rehabilitation activities. This paper explores the feasibility of utilizing ultrasonic shear wave technology, called MIRA, for quantification of damage in concrete slabs for the detection of freeze-thaw damage. Four slabs with varying levels of freeze-thaw damage were tested and two analysis techniques were developed to characterize the damage present. These methods involve the formulation of reconstruction images to analyze the subsurface condition, as well as the creation of a numerical index based upon recorded shear wave signal characteristics. The results of both analyses showed agreement both with each other and with the visual survey assessments for detection of freeze-thaw damage. However, the methods were also able to detect damage in portions of the slab where no visual cracks were observed. These techniques showed promise for an accurate nondestructive quantification of the extent of freeze-thaw damage, or similar damage manifestations, in concrete structures. Advantages of the methods include their applicability on in-situ concrete infrastructure for determining real-time concrete condition, without requiring previous measurements for comparative purposes.