1. Lattice modeling of cover cracking due to
reinforcement corrosion
Branko Šavija, Mladena Luković, Erik Schlangen

2. Lattice modeling of cover cracking due to reinforcement corrosion
Consec13, Nanjing
Content:
• Aim of the research
• Lattice model
• Corrosion induced cracking
• Conclusions

3. Lattice modeling of cover cracking due to reinforcement corrosion
Consec13, Nanjing
Why study corrosion induced cracking?
• Corrosion of reinforcement causes:
(1) Loss of steel cross-section
(2) Loss of bond between steel and concrete
(3) Change in ductility of steel (more brittle)
(4) Change in failure mode for beams (from shear to bond failure)
Serious problems preceded by
cracking of the concrete cover!

4. Lattice modeling of cover cracking due to reinforcement corrosion
Consec13, Nanjing
Research goal:
• Model corrosion induced cracking
using Delft lattice model
• Study the influence of concrete
meso-structure on the cracking
• Study the influence of stress-
release mechanisms
• Study the influence of pitting corrosion

5. Lattice modeling of cover cracking due to reinforcement corrosion
Consec13, Nanjing
Content:
• Aim of the research
• Lattice model
• Corrosion induced cracking
• Conclusions

6. Lattice modeling of cover cracking due to reinforcement corrosion
Consec13, Nanjing
Lattice models in fracture mechanics
Modelling of concrete fracture- set of beam/truss elements!
(Schlangen (1993)) (Schlangen & Qian (2009))
(Schlangen and Garboczi
(1997))

7. Lattice modeling of cover cracking due to reinforcement corrosion
Consec13, Nanjing
Lattice models in fracture mechanics
Some uses of the model:
ASR (Anaç et al.) Autogeneous shrinkage
(Luković et al.)

8. Lattice modeling of cover cracking due to reinforcement corrosion
Consec13, Nanjing
Content:
• Aim of the research
• Lattice models
• Corrosion induced cracking
• Conclusions

9. Lattice modeling of cover cracking due to reinforcement corrosion
Consec13, Nanjing
Corrosion induced cracking
• Corrosion products “migrate” into pores
around the steel and open cracks
• Needs to be taken into account in the
model!

10. Lattice modeling of cover cracking due to reinforcement corrosion
Consec13, Nanjing
Uniform corrosion:
The pressure is a function of:
•Bar radius
•Steel loss
•Migration of corrosion products
•Corrosion product density
•Young modulus of corrosion products
Not precisely quantified!
Cracking pressure is a function:
•Rebar position
•Concrete (local) mechanical properties

11. Lattice modeling of cover cracking due to reinforcement corrosion
Consec13, Nanjing
Uniform corrosion
Concrete as a heterogeneous material
Anm material model (Qian 2012)
Andrade et al. (1993)

12. Lattice modeling of cover cracking due to reinforcement corrosion
Consec13, Nanjing
Uniform corrosion
Influence of the porous zone (PZ) existence
on the cracking time (geometry 1)
Influence of the penetration of rust into open
cracks (geometry 1)
Delays the onset of damage!
Influences crack propagation kinetics!

13. Lattice modeling of cover cracking due to reinforcement corrosion
Consec13, Nanjing
Uniform corrosion

14. Lattice modeling of cover cracking due to reinforcement corrosion
Consec13, Nanjing
Pitting corrosion
• Caused by Cl penetration
• Non-uniform pressure exerted
• Different cracking behaviouor
Jang and Oh (2010)

15. Lattice modeling of cover cracking due to reinforcement corrosion
Consec13, Nanjing
Pitting corrosion
4α = 8α =Uniform
More: Šavija et al. (2013), Constr Build Mater 44, pp.626-638

16. Lattice modeling of cover cracking due to reinforcement corrosion
Consec13, Nanjing
Content:
• Aim of the research
• Lattice models
• Corrosion induced cracking
• Conclusions

17. Lattice modeling of cover cracking due to reinforcement corrosion
Consec13, Nanjing
Conclusions
• Corrosion induced cracking can be simulated using the Delft
lattice model
• Cracking patterns are influenced by concrete material structure
• Crack initiation is influenced by the porous layer around the
steel
• Crack propagation is influenced by penetration of corrosion
products into open cracks
• Pitting corrosion causes more large cracks compared to uniform
corrosion
Experiments to study the porous layer, corrosion product migration, and
rust properties are being performed by many researchers!

18. Lattice modeling of cover cracking due to reinforcement corrosion
Consec13, Nanjing
See our latest results at: http://microlab-m3c4.blogspot.com/
Contact: b.savija@tudelft.nl
Thank You very much for Your
attention!