Underwater Performance of a Hybrid Polymeric Repair Material to Seal Cracks in Concrete

This research program evaluated the crack sealing performance of a combination of hydrophilic and hydrophobic polyurethane grout, using two proportions of two different manufacturer’s grouts. The hybrid grouts were then injected underwater to determine if they could seal a crack in a concrete specimen. Successful performance of the hybrid polyurethane grout underwater consisted of sealing the crack, maintaining a 1 psi pressure, keeping the water clear during the injection phase, and having minimal floatation of the cured product. None of the hybrid grouts maintained the 1 psi pressure. However, the concrete specimens were qualitatively evaluated after the testing to determine how the grouts performed in the categories of penetration, number of gaps, adhesion, and shrinkage. The post evaluation also evaluated the final reacted product in the crack, characterizing the hybrid grouts as either flexible or rigid foams. Two of the four grout combinations were recommended based on the “good” rating they received in the post evaluation. Further study is recommended to determine if a hybrid polyurethane grout will fully seal cracks and sustain pressure underwater.