Capsules for asphalt self-healing

Capsules for asphalt self-healing

ICACSM 2017, Chennai

UK Mr T. Al Mansouri

Chile Dr J. Norambuena

Portugal Dr R. Micaelo

UK Dr A. García

Outline 1. Introdution to asphalt self-healing 2. Capsules for asphalt self-healing

3. Results 4. Conclusions

Performance

Roads suffer constant damage

• Cracking • Time dependent degradation • Ingress agressive substances

Time

Asphalt self-healing Problem: This process may take several days or weeks to complete. Crack

Crack

Asphalt concrete

hp

Ft

Ft



h( )

gh p

Ff

gh 

Fh

Contact point Fd

Fd

Healing material F f  Hydrostatic force Fh  Weight of the healing material

Ft  Surface tension force Fd  Losses (friction, etc) García A, (2011), “Self-Healing of open cracks in asphalt mastic”, FUEL. Fuel 93, 264-272.

F f  Fh  Ft  Fd  0

Asphalt self-healing. The solution Mechanical loading and/or moisture degrade the capsules that release the oil wherever it is more needed.

Asphalt Broken capsule

Local reduction of bitumen viscosity (This promotes the drainage of bitumen into the cracks)

Healing material

Inspiration MasterChef

Asphalt self-healing. Encapsulation procedure. 20 oC Sunflower oil

Alginate

Drops fall into the solution

2% Calcium 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… In the laboratory

In the asphalt plant

or Mixing temperature: 180 oC Capsule

• aprox. 20 s before the end of the mixing process, at the ambient temperature •