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Workshop on corrosion and corrosion protection in RC, January 2015, Delft
Non-destructive monitoring of corrosion induced cover
cracking in cement based materials
B. Šavija, J. Pacheco, M. Luković, S.A.S. Hosseini, E. Schlangen

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Workshop on corrosion and corrosion protection in RC, January 2015, Delft
• Introduction
• X-ray computed tomography
• Nanoindentation
• Summar
Outline:

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Workshop on corrosion and corrosion protection in RC, January 2015, Delft
• Maintenance costs are increasing
• Expensive remedial or repair works performed sooner than expected.
• (Reinforced) concrete is the most commonly used construction material in severe
environmental conditions (e.g. marine environment, cold/hot climates, etc.)
• Infrastructures (now) expected to have 100 (150) years service life!
Durability of concrete infrastructure is a major issue because:
• Reliable service life prediction models are needed!

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Workshop on corrosion and corrosion protection in RC, January 2015, Delft
Cracking of the concrete cover due to reinforcement corrosion
Corrosion of reinforcing steel causes pressure around the rebar, and
subsequent cracking of the cover

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Workshop on corrosion and corrosion protection in RC, January 2015, Delft
Cracking of the concrete cover due to reinforcement corrosion
• Corrosion products “migrate” into
pores around the steel and open
cracks?
Wong et al(2010)

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Workshop on corrosion and corrosion protection in RC, January 2015, Delft
• Introduction
• X-ray computed tomography
• Nanoindentation
• Summary
Outline:

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Workshop on corrosion and corrosion protection in RC, January 2015, Delft
What is CT scanning?

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Workshop on corrosion and corrosion protection in RC, January 2015, Delft
What is CT scanning?

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Workshop on corrosion and corrosion protection in RC, January 2015, Delft
Non-destructive study of corrosion induced cracking
BsC project by Seyed Amir Sajjad
Hosseini
Two cylindrical specimens
with Ø38 mm and length ≈58
mm
One hollow steel bar (Ø6 mm) per
specimen

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Workshop on corrosion and corrosion protection in RC, January 2015, Delft
Non-destructive study of corrosion induced cracking
Why use a hollow bar?
Beam-hardening effects!

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Workshop on corrosion and corrosion protection in RC, January 2015, Delft
Non-destructive study of corrosion induced cracking

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Workshop on corrosion and corrosion protection in RC, January 2015, Delft
Non-destructive study of corrosion induced cracking

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Workshop on corrosion and corrosion protection in RC, January 2015, Delft

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Workshop on corrosion and corrosion protection in RC, January 2015, Delft

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Workshop on corrosion and corrosion protection in RC, January 2015, Delft
Simulation using the lattice model:
•Only 0.5% of PVA fibres
(computational reasons)
•Not really strain-hardening!

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Workshop on corrosion and corrosion protection in RC, January 2015, Delft
Crack
development

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Workshop on corrosion and corrosion protection in RC, January 2015, Delft
• Introduction
• X-ray computed tomography
• Nanoindentation
• Summary
Outline:

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Workshop on corrosion and corrosion protection in RC, January 2015, Delft
Local mechanical properties of the tested points can be determined from the indentation
load and displacement measurement
What is nanoindentation?

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Workshop on corrosion and corrosion protection in RC, January 2015, Delft
Average rust E modulus:
67.9 GPa, 64.3 GPa, 49.4 GPa.

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Workshop on corrosion and corrosion protection in RC, January 2015, Delft
Average rust E modulus:
Lower!

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Workshop on corrosion and corrosion protection in RC, January 2015, Delft
What is different? EDS element mapping!

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Workshop on corrosion and corrosion protection in RC, January 2015, Delft
What is different? EDS element mapping!
With José

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Workshop on corrosion and corrosion protection in RC, January 2015, Delft
Rust in the cracks? EDS mapping!

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Workshop on corrosion and corrosion protection in RC, January 2015, Delft
• Introduction
• X-ray computed tomography
• Nanoindentation
• Summary
Outline:

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Workshop on corrosion and corrosion protection in RC, January 2015, Delft
Summary:
• X-ray computed tomography successfully used to study corrosion
induced cracking
• (dissolved) Corrosion products clearly “migrate” into voids and
open cracks, thereby relieving some of the expansion pressure
• SHCC showed superior resistance to corrosion induced cracking
compared to the control mixture
• Young modulus of rust is not a constant value, and depends on the
level of confinement! It decreases with the increase of damage,
thereby decreasing expansion pressure!
• More info: Šavija, B., Luković, M., Hosseini, S. A. S., Pacheco, J.,
& Schlangen, E. Corrosion induced cover cracking studied by X-ray
computed tomography, nanoindentation, and energy dispersive X-ray
spectrometry (EDS). Materials and Structures, 2014

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Workshop on corrosion and corrosion protection in RC, January 2015, Delft
Contact:
Branko Šavija
b.savija@tudelft.nl
Microlab, CiTG, 6.05
+31152788986