Capsules for asphalt self-healing ICACSM 2017, Chennai, India - - PDF document

See discussions, stats, and author profiles for this publication at: https://www.researchgate.net/publication/319620324

Capsules for asphalt self-healing ICACSM 2017, Chennai, India (Presentation for the Rilem week, 2017)

Presentation · September 2017

CITATIONS READS

665

4 authors, including: Some of the authors of this publication are also working on these related projects: Optimisation of Porous Asphalt Mixtures View project Development of an experimental prototype of a mid rise Cross Laminated Timber building View project Tariq Al-Mansoori University of Al-Muthanna

17 PUBLICATIONS 125 CITATIONS

SEE PROFILE

Alvaro García University of Nottingham

141 PUBLICATIONS 2,462 CITATIONS

SEE PROFILE

The user has requested enhancement of the downloaded file.

Capsules for asphalt self-healing

ICACSM 2017, Chennai Mr T. Al Mansouri Dr A. García Dr R. Micaelo Dr J. Norambuena UK Chile Portugal UK

Outline

• 1. Introdution to asphalt self-healing
• 2. Capsules for asphalt self-healing
• 3. Results
• 4. Conclusions

Roads suffer constant damage

Time Performance

• Time dependent degradation
• Cracking
• Ingress agressive substances

Asphalt self-healing

Crack

p

gh 

p

h

Contact point Asphalt concrete



Crack

Asphalt self-healing

 

 gh ) ( h

Healing material

f

F

h

F

t

F

t

F

d

F

d

F



t

F



f

F



d

F



h

F Surface tension force Hydrostatic force Weight of the healing material Losses (friction, etc)

   

d t h f

F F F F

García A, (2011), “Self-Healing of open cracks in asphalt mastic”, FUEL. Fuel 93, 264-272.

Problem: This process may take several days or weeks to complete.

Asphalt self-healing. The solution

Broken capsule Asphalt Healing material Local reduction of bitumen viscosity

(This promotes the drainage of bitumen into the cracks)

Mechanical loading and/or moisture degrade the capsules that release the oil wherever it is more needed.

Inspiration MasterChef

Asphalt self-healing. Encapsulation procedure.

Alginate 2% Calcium solution Sunflower oil

20 oC

Drops fall into the solution

This is one of our capsules…

The capsules have an internal porous structure that contains approx. 80% oil

…this is how we mix the capsules in asphalt…

Capsule

• r

In the asphalt plant In the laboratory

• aprox. 20 s before the end of the mixing

process, at the ambient temperature

• <0.5% by weight of total mixture. 1 ton
• f asphalt <5kg of capsules

Mixing temperature: 180 oC

Capsule

…and this is asphalt containing capsules.

…and this is asphalt containing capsules.

Note: this is dense asphalt mixture, maximum size of aggregates 20mm that has been roller-compacted at 140 oC.

This is how we test self-healing

100 mm 60 mm 150 mm Notch 5 mm

100 mm

• 20 ºC

Step B. Break the capsules Step C + ºC 20 Temperature chamber Steel mould Healing time: 6- h 192 F + 20 ºC Steel plate Step A: Break the beam F

Healing level = strength before resting/strength after resting

• 1. Place a flexible plastic membrane in the

crack

• 2. Compress the beam
• 3. Remove the plastic membrane

Plastic membrane

Capsules resist mixing and compaction

1.12 1.27 1.53 31.29 49.2 56.31 10 20 30 40 50 60 70 80 90 100 Caps 0.10 0.25Caps 0.50Caps

Capsule content in mixture (%)

Before compression After compression

We simulate many years of traffic by compressing the test samples. In this way we can break the capsules and release the oil.

F + ºC 20 Steel mould Steel plate Plastic membrane

Capsules resisted mixing and compaction. Capsules broke during compression.

Asphalt self-healing

10 20 30 40 50 60 70 80 90 100 50 100 150 200 Healing level (%) Time (h) WO/C 0.10% Caps 0.25% Caps 0.50% Caps

No capsules

Remember: Healing level = strength before resting/strength after resting

Effect of temperature on asphalt self-healing

10 20 30 40 50 60 70 80 90 100

• 5

5 15 25 35 45 55 Maximum healing level (%) Healing temperature (oC) With capsules Without capsules

10 20 30 40 50 60 70 80 90 100 50 100 150 200 Healing level (%) Time (h) WO/C 0.10% Caps 0.25% Caps 0.50% Caps

No capsules

After 100 h resting

Properties or asphalt mixture

• 1. Air void content
• 2. Particle loss test
• 3. Water sensitivity
• 4. Rutting susceptibility
• 5. Stiffness modulus
• 6. Fatigue life

Properties or asphalt mixture

Conclusions

• 1. Capsules containing healing agents can be mixed in asphalt and resist mixing

and compaction.

• 2. Capsules improve asphalt self-healing of asphalt mixture, even at low

temperatures.

• 3. Mechanical properties of asphalt mixture are not truly affected by the

presence of capsules.

• 4. Our capsules are too big. They should be smaller, to avoid affecting fatigue

life.

• 5. Capsules for asphalt self-healing are ready to be tested on-site.

Thank you

alvaro.garcia@nottingham.ac.uk

October 2017. First trial of a self-healing road with capsules!!