What to Look for When Concrete Deteriorates

As with all building components, concrete slabs, beams, and columns will inevitably deteriorate and need repair throughout the lifetime of a building. Most concrete deterioration is linked to the corrosion of embedded metal elements, such as steel reinforcement bars. As the steel elements rust, it expands and occupies more space than the original steel, slowly building up pressure on the concrete until the concrete separates from the steel reinforcement. In the most extreme cases, the concrete will separate from both the steel and surrounding concrete, resulting in a condition known as “spalling.” Spalled concrete can be easily identified by visual inspection; it would be hard to miss a chunk of concrete missing in a wall or beam!

However, deteriorated concrete that separates from the steel rebar, but not the surrounding concrete, can be trickier to find. This deterioration is known as “delamination.” Identifying delaminated concrete requires non-destructive testing, such as sounding of the concrete elements, which tends to be the most common cost-effective option. Areas of delaminated concrete can be found by listening for hollow areas, which make a low, drum-like noise, while sounding the concrete with a hammer or by chain dragging. The hollow sound is caused by the air gap between the separated concrete and rusted steel. If you’ve noticed some suspicious-looking concrete in your building, reach out to ETC to help evaluate your building today.