CRUFI - Modelling of transient thermal and moisture performance of concrete structures and prediction of reinforcement corrosion in (recycled) concrete

Concrete structure with damaged metallic reinforcement
© Shutterstock / Francesco Scatena
Taking into consideration temperature, moisture, corrosivity and time as elements, transient predition models for reinforcing corrosion will be developed in this project.

To reduce demolition waste and limit sand and gravel mining, the use of recycled aggregates in concrete gains in importance. Additionally, chloride-contaminated material shall be used, which hardly happens up to now due to the chloride-induced corrosion risk. In this project, the durability of concrete with and without chloride-containing recycled aggregate will be investigated with regard to different exposures, and under consideration of the CO2 binding capacity. Therefore, taking into consideration temperature, moisture, corrosivity and time as elements, transient predition models for reinforcing corrosion will be developed.

Project goals

Usually, the reinforcing steel is protected against corrosion due to the alkalinity of the concrete. When carbonation occurs, this protection can get lost. While carbonation is fast in dry concrete and much slower in moist or wet concrete, corrosion behaves conversely. Whereas calculation models for carbonation are already available, they are missing for the transient prognosis of the corrosion progress with respect to the temperature, humidity, time and corrosivity of concrete. In addition to that, detailed material properties for the time dependent liquid and vapour transport in the different areas of concrete are required. Up until now, effective properties for the transfer through the concrete layers seemed to have been sufficient for the moisture resistent material.

On the basis of these investigations, both hygrothermal simulation tools and evaluation models will be developed. These will enable the prediction for any application and operation concerning the questions of whether and to which extent a corrosion risk of the reinforcement has to be feared, and how this can be prevented. For instance, by changing assembly or materials, or by adding coatings. For that purpose, normal, recycled, and CO2-absorbant concretes are considered.

Owing to the new prediciton possibilities, corrosion problems can be avoided, as well as allow to both develop cost efficient refurbishment measures and to extend the use of recycled concrete while improving the carbon footprint of concrete structures. 

Project partners

  • Fraunhofer Institute for Building Physics IBP (Germany)
  • University of Applied Sciences Munich (Germany)
  • FH Campus Wien – University of Applied Sciences (Austria)
  • Federal Centre for Technological Education of Minas Gerais (Brazil)
  • Trägerverein Institut für Holztechnologie Dresden e.V. (Germany)
  • User Comittee consisting of 24 SMEs from Germany, Austria and Brazil
© Fraunhofer IBP
Calculation of transient heat and moisture behavior in building components using real climatic conditions and taking into account all relevant transport and storage mechanisms.
© Fraunhofer IBP
WUFI Corr - Corrosion rate as a function of relative humidity and temperature as well as the "corrosiveness" of the embedding material.