Effect of cracking and healing on chloride transport in OPC concrete
- Norwegian Building Research Inst., Oslo (Norway)
- Univ. Laval/CRIB, Quebec (Canada)
The effects of cracking and self healing on chloride migration and compressive strength were investigated on w/c = 0.40 concrete. Internal cracking due to rapid freeze/thaw exposure resulted in a compressive strength reduction of 68--40% and a reduced Ultrasonic Pulse Velocity (UPV) to 78--45% of undamaged values. The rate of chloride migration through 15 mm thick slices under a 10 volt electric field was increased by 2.5--8 times, and the chloride penetration time through the slices was reduced from 64 to 0 hours for the most severe cracking. The increased chloride transport due to cracking could be predicted fairly well by characterizing the cracks using a square grid crack pattern model. Self healing by storage of cracked specimens in lime saturated water at 20C for three months after stop of freeze/thaw exposure gave recovery in UPV of 50--100%, but compressive strength recovered only 0--10% of the initial value. Rate of chloride migration in the self-healed concretes was reduced by 28--35%, and penetration time was increased compared to newly cracked concrete. The chloride migration through an air entrained concrete with the same w/c ratio (no internal cracking after more than 300 cycles of rapid freeze/thaw exposure), was unaffected by freeze/thaw.
- OSTI ID:
- 276761
- Journal Information:
- Cement and Concrete Research, Vol. 26, Issue 6; Other Information: PBD: Jun 1996
- Country of Publication:
- United States
- Language:
- English
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