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How to Improve Autogenous Healing in Concrete?

Autogenous healing is the ability of the concrete to repair or heal the cracks in them in the presence of moisture.

How to Improve Autogenous Healing in Concrete?


 Autogenous healing in concrete can be enhanced and improved by following ways:

  1. Fiber in Autogenous-Healing of Concrete
  2. Shrinkable Polymers in Autogenous-Healing of Concrete
  3. Mineral Admixture in Autogenous-Healing of Concrete

1. Fiber in Autogenous-Healing of Concrete

The incorporation of fibers in concrete helps to enhance the autogenous self-healing property of concrete. Fibre is an important material that is used for Fibre-Reinforced Concrete (FRCC) as well as in Engineered Cementitious Composites (ECC). 
Fig.1. Fiber in Autogenous Healing of Concrete

The arrangement of fibres in a randomly distributed manner helps to bridge the cracks. These bridging helps to decrease the crack width and hence prevent the migration of aggressive agents like chloride ions and carbon-di-oxide. Hence, these activities improve the autogenous self-healing capacity of the concrete. 
On the other side, the design of FRCC, ECC and HFRCC is very costly and it is a great challenge to maintain the homogeneity of fibres in the matrix in a consistent manner to facilitate self-healing property.  

2. Shrinkable Polymers in Autogenous-Healing of Concrete

Shrinkable Polymers are polymers that shrinks when they are activated by heating in a specific condition. One of the example of shrinkable polymers are polyethylene terephthalate (PET) tendons. The stress created using during this shrinking is used to bring the crack tip closure for efficient healing.

Fig.2.  Shrinkable Polymers in Autogenous-Healing of Concrete

As per the study conducted by Cardiff University Self-healing research team, the restrained polymer tendons that are used in concrete is activated thermally once the initial curing of the concrete is done. Once the tendon gets activated, the used polymer tendon closes the performed macrocracks and impart significant stress across the crack faces. This would enhance the autogenous self-healing process in concrete.

3. Mineral Admixture in Autogenous Healing of Concrete

The self-healing capacity of concrete can be improved by introducing mineral admixture and supplementary cementitious materials (SCMs). The minerals introduced in concrete can help self-healing process in the below ways:
  1. To remain unhydrated after the initial mixing stage of the concrete.
  2. To undergo reaction and produce expansive hydrated products that would heal the cracks.
Fig.3. Mineral Admixture in Autogenous Healing of Concrete

The different types of SCMs that can be used to auto heal the concrete cracks through autogenous self-healing are silica fumes, fly ash and blast-furnace slag and expansive minerals like lime, bentonite clay, crystalline additive (CA), calcium sulphoaluminate, magnesium oxide.


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