19 June 2001
CR-1: REPAIR SMALL TO MEDIUM CRACKS BY EPOXY GROUT INJECTION
: Cracks caused
by weathering, deterioration,
or reinforcing steel
corrosion allow water to penetrate the structure.
Description of Repairs: Filling and sealing small to medium cracks by injecting
a low-viscosity urethane and sealing the outside with an epoxy paste. Routing
and cleaning of cracks are performed with conventional hand and power tools.
Injection for smaller jobs can be done with a hand-operated caulking gun. Large
jobs are usually done with special equipment.
a. Low-Viscosity Epoxy - Select a urethane suitable for wet surfaces
and underwater application that is compatible with crack volume, crack
movement, and equipment to be used for injection. See Paragraph 188.8.131.52.
b. Sealing Epoxy - Use a quick-setting epoxy paste adhesive suitable
for underwater application that has good bonding characteristics for concrete
a. Rout out cracks to remove all deteriorated and loose concrete and
aggregate. Clean area to receive sealing epoxy with wire brush, high-pressure
water jet, or sandblasting.
b. Drill injection holes every 15 cm (6 inches) along the length of the
crack for larger jobs with deep cracks. Install a tube or one-way polyethylene
valve in the holes as injection ports.
c. Repair small and shallow cracks with a hand gun, injection ports
may be openings left in the sealing epoxy every 15 cm (6 inches).
Repair Procedures: See Figure 7-2.
a. Perform repairs when ambient/water temperature is at least 10C
b. Seal the outside surface of the crack with the epoxy paste, carefully
sealing around the injection ports.
c. After the surface seal has set, inject the urethane grout, starting at
the bottom port for a vertical crack. Continue injection until grout shows in the
next port then continue up the crack until the entire crack is filled.
d. Plug the port holes with the sealing epoxy paste.