Accelerated Autogenous Healing of Concrete Pipe Sections with Crack and Decalcification Damage

Abstract

Many concrete water-distribution systems are past their service life and need repair due to leaks associated with cracks. Autogenous healing of concrete cracks and leaks can sometimes occur if the chemistry of distributed water is favorable, whereas small leaks eventually cause pipe failures if water chemistry is unfavorable. This study evaluates autogenous healing of simulated potable-water concrete distribution pipe leaks. Cement mortar pipe sections with leaks created by controlled cracking, extremes of decalcification, and water chemistry are studied, with the trajectory of leaks (and autogenous repair) monitored by permeability. Cracked specimens show significantly high permeability compared with decalcified specimens. The healing solutions reduce the permeability of the damaged specimens by as much as a factor of 12.5 for cracked specimens and by a factor of 3.5 for decalcified specimens. The healing process essentially requires solutions with supersaturated amounts of calcium carbonate to significantly reduce permeability of the cracked or leached specimens.