Concrete is a material that is, metaphorically and literally, opaque. While in some situations it can exhibit brittle behavior such as cracking like glass, unlike glass those cracks cannot be fully assessed visually like they can be through a translucent medium. However, unlike a traditional building material like wood, concrete does not change audible properties to reflect its mechanical integrity. For example, knocking on a wooden component and listening to the sound can inform a trained ear as to the thickness or hollowness of the component, but this is not the case with concrete. Additionally, as a material that can have brittle behavior and thus is prone to fractures around stress concentrations caused by small flaws, common non-visual testing methods like taking small core sample are not applicable either. Thus, it is necessary to employ more creative techniques to assess the structural integrity of the concrete components of a building. This is where x-ray technology can assist.
The idea of using x-ray technology can make some uneasy, largely due to the association with medical procedures and the necessary safety precautions around that. However, x-ray for concrete inspection is not directed at a human body and uses “no live nuclear isotopes”1. Additionally, technicians are trained specifically in the safe use of this technology.
Benefits of concrete inspection via x-ray include “smaller exclusion zones, no film… real time digital picture[s] in seconds…20x more accurate than GPR (radar)” and ability to easily share the images digitally without having to wait for an upload1. Real-time processing speeds, such as those available with x-ray, can change the entire nature of a service. Whereas tests with a longer process time necessitate a technician to guess about where problem areas might be and test those, tests that can scan across a wall in real-time have a better chance to catch even unexpected errors as well as inform other same-day tests that are to be performed. The ability to instantly share digital copies of test results instead of waiting for data-entry can also impact the speed at which a technician is free to perform the entire service, and the thoroughness with which they are instructed to test.
Because of concrete’s aforementioned brittleness, in building applications this material is often reinforced by metal “boning” called rebar. Due to concrete’s tendency to crack at points of regionally high stress concentrations, rebar can contribute both to the overall strength and resilience of the concrete component, but also to small flaws and cracks within it. X-ray technology can detect these cracks and flaws, which are usually benign. This imaging technology can also be useful at detecting the exact location of rebar beams, if drill holes or cuts need to be strategically placed in building remodeling.
Concrete inspections can also be done via more traditional methods like radar imaging, but the speed and accuracy of x-ray is pushing the industry increasingly in that direction. Whichever method is chosen, concrete components should be inspected regularly as per the design specifications in order to function optimally and safely and avoid stressing other, connected building components.