Concrete flaking is a common issue that can be caused by a variety of construction defects, such as improper preparation of reinforcing steel, incompatible supporting metals, metal bars placed too close to the surface, stress fractures due to excessive weight, insufficient concrete cover or poorly poured concrete.
Chipping
is a term used to describe areas of concrete that have cracked and delaminated from the substrate. This can be caused by freeze-thaw cycles, the expansive effects of the alkaline silica reaction, or exposure to fire. However, the most common cause of chipping is corrosion of embedded steel reinforcing bars or steel sections. Corrosive steel can expand up to ten times its original volume, putting stress on the surrounding concrete.Carbonation is another natural process that can lead to concrete flaking. Water seeps into the concrete and causes other elements, especially the reinforcing bars embedded in the concrete, to corrode. This creates bulges and cracks on the surface of the concrete. Poor quality steel can also lead to chipping. If descaling of concrete is not controlled, structural problems tend to accelerate and spread, making them more unstable.
Chipping can be natural or man-made and there are steps that must be taken in order to prevent and repair it. Chipping can have serious consequences in terms of health and safety, structural integrity and asset value. The third ingredient in concrete, water, can also cause chipping if it is added too much during preparation. Different atmospheric conditions such as moisture content, temperature rise and corrosion can also lead to concrete flaking. If a structure is allowed to deteriorate, its value will decrease and maintenance costs will increase as corrosion and scaling become more widespread. Deicing chemicals only make matters worse by allowing more water to migrate into concrete, increasing the size and depth of husking failures when freezing occurs.
Chips in concrete can be avoided if proper techniques are used during the pouring process and if the concrete is handled with care. Robson Forensic offers experts across the country who can provide first-hand knowledge and experience around chipping issues in their specific geographic region. The reason why some concrete structures exhibit widespread flaking while others appear to be in good condition is due to a combination of age, maintenance, concrete quality, concrete cover depth and local environmental conditions. If left unchecked, chipping will tend to accelerate and spread so that eventually the structure could become unstable. It is important to take preventive measures in order to avoid costly repairs and ensure structural integrity.
