Left – concrete crack | Right – self-sealed crack
Self-Sealing is the ability to stop the flow of water by automatically closing cracks.
is based on principles that are very similar to the processes that occur during the hydration and hardening of concrete.
Importance of Self Sealing
- Decreases water permeability (Increases corrosion resistance)
- Re-seals new cracks that form during shrinkage, settling, etc.
- Decreases long-term maintenance and repair costs
Four Main Mechanisms
- Physical – Filler Effect and the swelling of Cement Matrix
- Chemical – Continued Hydration and the precipitation of insoluble products
Filler Effect
- Temporary Sealing – Debris carried into the crack by flowing water is deposited and clogs the flow of water.
- Easily removable – high water pressure will wash away debris or degrade over time
Continued Hydration
- Occurs when un-hydrated cement particles are exposed to water from the crack
- The hydrating cement matrix seals by growing into the void between the crack walls
- Ongoing process as long as un-hydrated cement is available
Precipitation
- Main contributor to self-sealing
- Formation of insoluble crystalline precipitates occurring over several weeks which deposits across the width of the crack
- Krystol products act as a catalyst to accelerate the natural formation of precipitates.
- KIM increases sealing capacity from 0.2 mm to 0.5 mm crack widths
