Section 7: Crack Repair – Surface SealingAnchor: #i1004642
Occasionally there is a need to seal cracks to prevent infiltration of water, chlorides, and other contaminants. While other crack sealing techniques can restore capacity or provide for complete filling of a crack, the methods outlined in this section only cover sealing the cracks at the outer surface of the concrete.Anchor: #i1004652
Method 1: Rout-and-Seal Cracks
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- Routing and sealing cracks can be an effective way to prevent water infiltration in cracks in which a small amount of movement is anticipated due to service loads, thermal effects, or other causes. Anchor: #TBPGBBRV
- When routing a crack, the Contractor should use a grinder to create a V-shaped groove, with the crack centered in the groove. Though it can vary depending on the application, the grooves should typically be about 3/8 inch deep. Anchor: #ODQFXVLJ
- For cracks in which a significant amount
of movement is anticipated, bond breaker tape should be placed at
the bottom of the groove prior to sealing. The tape must stay at
the bottom of the groove in order to be effective. The bond breaker
allows for 2-sided rather than 3-sided adhesion, which permits much
greater elasticity of the sealant.
NOTE: Although good in principle, it is difficult to place bond breaker tape in the bottoms of the grooves such that the tape will not move during application of the sealant. If the bond breaker moves up it can reduce or eliminate the bonding surface on one side of the joint, eliminating their effectiveness. When used, the Contractor must take great care to ensure that tape stays in its intended location.
- After grooving, ensure substrates are clean and sound. Remove any contaminants, including laitance, oil, dust, debris, or other foreign particles. Anchor: #XXIVRBCE
- Fill the groove using a preapproved Class 4 low-modulus silicone meeting the requirements of DMS 6310, Joint Sealants and Fillers.
Method 2: Surface Sealing
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- Sealing the surfaces of cracks simply involves applying an epoxy directly over the crack to prevent infiltration of water, chlorides, and other contaminants. Anchor: #HBICNBEU
- Sealing the surfaces of cracks should only be employed when no significant crack movement is anticipated. This can apply to minor cracks in compression members, or in cracks that occur in prestressed members as a result of fabrication, detensioning, or handling issues. Anchor: #ERQSPTWX
- For sealing cracks at the outer concrete surface, apply a preapproved Type VIII or Type X epoxy that meet the requirements of DMS 6100, Epoxies and Adhesives. Work the epoxy into the crack, then remove any excess epoxy from the surface before it sets.