Self Healing of Longitudinal Cracks in Utility Concrete Pole

Abstract

The precipitates in cracks in an actual utility concrete pole exhibiting self healing which had been in service for 34 years in a freezing and thawing environment were analyzed and the mechanism of self healing was discussed. CaCO3 was observed at the surface of the pole, and it was guessed from the condition of precipitation that water accumulated inside the pole had flowed through the crack to the surface. CaCO3 and ettringite were precipitated in the cracks inside the pole. While cracks approximately 200 μm wide were not completely healed, cracks with a smaller width of 50 to 100 μm were blocked up with precipitates. Precipitates were mainly observed near the interface between the matrix and crack, and much less near the interface between the aggregate and crack. The steel inside the concrete was protected against corro- sion by self healing of cracks.