Digital Image Correlation of Concrete Slab at University of Tennessee, Knoxville

Abstract

Assessment and management of aging concrete structures in nuclear power plants require a more systematic approach than simple reliance on existing code margins of safety. Some degradation mechanisms of concrete manifest themselves via swelling or by other shape deformation of the concrete. Specifically, degradation of concrete structures damaged by the alkali-silica reaction (ASR) is viewed as one of the dominant factors impacting the structural integrity of aging nuclear power plants. Structural health monitoring of concrete structures aims to understand the current health condition of a structure based on heterogeneous measurements to produce high-confidence actionable information regarding structural integrity that supports operational and maintenance decisions. Numerous nondestructive examination techniques (i.e., thermography, digital image correlation, mechanical deformation measurements, nonlinear impact resonance [DIC] acoustic spectroscopy, and vibro-acoustic modulation) are used to detect the damage caused by the ASR. DIC techniques have been increasing in popularity, especially in micro-and nano-scale mechanical testing applications due to its relative ease of implementation and use. Advances in computer technology and digital cameras help this method moving forward. To ensure the best outcome of the DIC system, important factors in the experiment are identified. They include standoff distance, speckle size, speckle pattern, and durable paint. These optimal experimental options are selected basing on a thorough investigation. The resulting DIC deformation map indicates that this technique can be used to generate data related to the degradation assessment of concrete structure damaged by the impact of the ASR.