| Date post: | 18-Aug-2015 |
| Category: |
Documents |
| Upload: | branko-avija |
| View: | 2 times |
| Download: | 0 times |
1
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
2
Workshop on corrosion and corrosion protection in RC, January 2015, Delft
• Introduction• X-ray computed tomography• Nanoindentation• Summar
Outline:
3
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!
4
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
5
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)
6
Workshop on corrosion and corrosion protection in RC, January 2015, Delft
• Introduction• X-ray computed tomography• Nanoindentation• Summary
Outline:
7
Workshop on corrosion and corrosion protection in RC, January 2015, Delft
What is CT scanning?
8
Workshop on corrosion and corrosion protection in RC, January 2015, Delft
What is CT scanning?
9
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 mmOne hollow steel bar (Ø6 mm) per specimen
10
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!
11
Workshop on corrosion and corrosion protection in RC, January 2015, Delft
Non-destructive study of corrosion induced cracking
12
Workshop on corrosion and corrosion protection in RC, January 2015, Delft
Non-destructive study of corrosion induced cracking
13
Workshop on corrosion and corrosion protection in RC, January 2015, Delft
14
Workshop on corrosion and corrosion protection in RC, January 2015, Delft
15
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!
16
Workshop on corrosion and corrosion protection in RC, January 2015, Delft
Crack development
17
Workshop on corrosion and corrosion protection in RC, January 2015, Delft
• Introduction• X-ray computed tomography• Nanoindentation• Summary
Outline:
18
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?
19
Workshop on corrosion and corrosion protection in RC, January 2015, Delft
Average rust E modulus:67.9 GPa, 64.3 GPa, 49.4 GPa.
20
Workshop on corrosion and corrosion protection in RC, January 2015, Delft
Average rust E modulus:Lower!
21
Workshop on corrosion and corrosion protection in RC, January 2015, Delft
What is different? EDS element mapping!
22
Workshop on corrosion and corrosion protection in RC, January 2015, Delft
What is different? EDS element mapping!
With José
23
Workshop on corrosion and corrosion protection in RC, January 2015, Delft
Rust in the cracks? EDS mapping!
24
Workshop on corrosion and corrosion protection in RC, January 2015, Delft
• Introduction• X-ray computed tomography• Nanoindentation• Summary
Outline:
25
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
26
Workshop on corrosion and corrosion protection in RC, January 2015, Delft
Contact:Branko Š[email protected], CiTG, 6.05+31152788986
