Monitoring for sustainable management of concrete structures

In the 1960s and 1970s, many concrete structures were built, mostly designed to last 50 years. These structures are now slowly beginning to show signs of aging. For infrastructure structures, for example, the impact and consequential damage can be significant if timely action is not taken. The Scientific and Technical Center for the Construction Industry (WTCB) therefore advocates sustainable management of concrete structures in which monitoring tools have an important role to play.

Text | Roel van Gils  Image | WTCB

"Being aware of the current condition of a concrete structure means that you can intervene better and faster when abnormalities are observed," says Bram Dooms, Deputy Laboratory Head of Concrete Technology at the WTCB. "These are usually deviations that are not visible from the outside (yet). That way you can carry out any repairs faster and easier, with less cost and less disruption. However, today we live in an economic reality where no money is spent, provided it is not very urgent. When concrete damage occurs, unfortunately, it is usually waited too long with the result that the consequential damage is actually much greater. Monitoring tools can turn that tide."

Measurement of volumes using a series of photographs and photogrammetry.

MIT Cambridge

A study by the Massachusetts Institute of Technology in Cambridge - one of the most prestigious engineering universities in the world - shows that the cost of monitoring a bridge, for example, does not outweigh the eventual consequential damage, Dooms continues. "By using monitoring tools, any damage is noticed much faster and the repair costs and disruption are many times smaller. Proof that monitoring does make sense. The drama with the Morandi bridge in Genoa could have been prevented this way. The same applies to the falling debris in the various tunnels in Belgium, such as the Rogiert Tunnel and Leopold II Tunnel. And so there are many more examples where monitoring can certainly be of great added value in the infrastructure sector."

Optical fiber technology

Meanwhile, a wide variety of innovative monitoring techniques are already available on the market to remotely monitor the damage state of structures and measure deformations, vibrations, stresses and environmental conditions, among other things. But also to check the durability of concrete repairs carried out. Dooms gives some examples: "With optical fiber technology, deformations or temperature fluctuations can be noticed and monitored in a very precise way. This is all fully automated with a notification being generated if a threshold is exceeded. Another application is cathodic protection, which uses electric current to prevent the corrosion of reinforcement in concrete. The operation has already proven itself. Reference electrodes are used to check whether the protective effect is also working."

With a fine optical fiber cable, strain and temperature can be measured at tens to thousands of locations along the cable.

And so there are many more monitoring techniques available on the market, with even a role for satellites and drones. "With a drone equipped with specialized equipment, concrete structures can be very accurately measured in 3D and scanned for concrete damage, even in hard-to-reach locations. A useful diagnostic tool. In short, plenty of opportunities to nip concrete damage in the bud."

The WTCB, in cooperation with the VCB and FEREB, recently organized a webinar on the sustainable management of concrete structures. This included a discussion of various monitoring techniques. Via the website is to watch the webinar back.