Growing interest among construction companies in selecting the correct exposure class for concrete

Many construction contractors opt for exposure classes that are higher than necessary in their projects. This results in unnecessary climate impact and increased costs. That is the view of Anders Lindvall, Technical Specialist at C-lab, Thomas Concrete Group’s research and development division, who is receiving a growing number of inquiries from clients and structural designers about which exposure class to choose.

"Exposure class describes how the surrounding environment affects concrete and determines which concrete compositions and cover depths may be used. If the exposure class is set too high, cement content increases without reason and the possibility to use low-carbon concrete is reduced," says Anders Lindvall at C-lab.

C-lab was founded in 1992 and operates in three areas that include material and laboratory testing, technical consultancy, damage assessments and R&D. Their experience shows that overly strict exposure classes are chosen in many projects, often to create additional safety margins. In recent years interest from contractors seeking support in choosing the correct exposure class has increased.

"There is a perception that higher classification is always better. In practice it leads to more expensive structures, more complex work steps and higher climate impact. We end up with unnecessarily robust constructions that do not correspond to what is required in the real environment," says Anders.

Proven results in ongoing projects

C-lab has been involved in several major projects where adjusted exposure classes have delivered both climate related and economic benefits. One example is the new Central Station in Gothenburg, where C-lab and NCC developed solutions that enabled a more suitable concrete choice, reducing carbon emissions by 42,000 tons.

Support for the entire industry

C-lab supports both Thomas Concrete Group internally and clients directly in its role as consultant. C-lab is active in industry associations and has led the development of Concrete Report 11 from the Swedish Concrete Association, which provides guidance on how exposure environments can be defined.

"Putting the right concrete in the right place is the core principle. It benefits the end customer, reduces climate impact and ensures a structure that lasts for its intended lifespan. The report is a valuable tool but is not always used. That is why we want to be involved early in projects to help select the correct class from the start," concludes Anders Lindvall.