Concrete cover & carbonation testing

Concrete cover & carbonation testing

The corrosion of steel reinforcement due to carbonation remains a main contributor to concrete failure. Carbonation is environmentally induced and relies upon the presence of moisture. To detect this concrete cover & carbonation testing can be carried out.

The process of carbonation is difficult to avoid with untreated concrete exposed to weather. As soon as concrete is exposed to air and co2, carbonation can take effect. Moisture and calcium hydroxides within concrete react with carbon dioxide to form calcium carbonate which in turn reduces the concretes natural alkalinity. It is this change in the chemical characteristics of reinforced concrete that poses a profound threat to its structural integrity: as carbon dioxide travels deeper into the concrete and approaches the depth of embedded steel, the passivating (thin protective) layer around the reinforcement is broken down by the process of carbonation, exposing the steel to the corrosive effects of air and water.

As the steel reinforcement rusts and expands in volume it places force on the concrete which cracks and spalls, causing the rate of failure in the surrounding area to increase exponentially.

Concrete carbonation may advance at a rate of 1mm to 5mm per year. Carbonation testing in accordance with BSEN 4630 is paramount to identify the extent of carbonation, generally a simple method of testing will identify the depth of carbonation.

To coincide with carbonation testing, we stock various equipment to determine the depth of embedded reinforcement. Non-destructive equipment such as electromagnetic or GPR scanners will be deployed along with relevant carbonation testing kits including Phenolphthalein indicator solution to determine if carbonation levels are in excess of embedded reinforcement.

Please contact a member of our surveying team to discuss your building materials testing requirements or to book testing.