15 March 2001
SUMMARY OF CRACK REPAIR
2.1. Sealant Selection. Select the proper sealant material for the area being repaired (Chapter
6, "Crack Sealants"); however, the sealant selected must conform to appropriate specifications
and be authorized by base engineers before use. Normally, it should match adjacent sealants.
However, neoprene compression seals should not be used for cracks. The repair should be
timed such that sawed-out cracks are not exposed for more than 24 hours before sealing. If the
cracks get wet, the repair operation must stop until the cracks are completely dry. The cracks
may be dried with a heat lance (Figure 9.3.).
2.2. Shape Factor and Recess. Saw or rout (Figures 9.1. and 9.2.) the crack to the proper
width and depth to reach the desired shape factor and recess (Chapter 8, "Shape Factors")
recommended by the manufacturer of the sealant to be used. For silicone sealants, use of a
backer rod in lieu of separating tape is recommended (Chapter 6, "Crack Sealants"). Small
cracks may be sawed by hand (Figure 10.1.).
2.3. Sandblasting. Clean the crack faces by sandblasting using the multiple pass technique
(Figure 10.3.). While standing to one side of the crack, pass the wand along the crack face at an
angle to allow a strong blast on one crack face; then step to the other side of the crack and
2.4. Removing Loose Material. Blow debris out of the crack using compressed air; then clean
the crack with high-pressure water (Figure 9.4.). There must be no loose material in the bottom
of the crack.