15 March 2001
2.5. Vacuuming. Clean the area around the crack with a broom or vacuum sweeper to prevent
debris from reentering the crack before sealing (Figure 9.5.). Compressed air may be required to
clean crack after the power broom is used.
2.6. Cleanliness. Remember that the cleanliness of both crack faces is extremely important!
Dirty crack faces are a major cause of loss of adhesion of the sealant to the crack face and
subsequent failure of the crack repair. Place the sealant within 24 hours after sandblasting. If
sealant is not placed within 24 hours sandblast the face again, clean the crack with high-pressure
water and air, sweep and vacuum the surface around the crack, and then seal. If a finger wiped
along the joint face picks up dirt or dust, the joint or crack face is dirty and must be cleaned.
2.7. Backer Rod. Place the backer rod immediately prior to sealing the crack (Figure 9.6.). The
backer rod must be at least 25 percent larger in diameter than the width of the crack and must be
placed at the proper depth for the shape factor of the sealant being used (Figure 7.1.). Seal the
crack from the bottom up and from beginning to end in one stroke without interruption, when
practical (Figure 11.1.).
2.8. Foreign Object Damage. After the crack repair operation is complete, clean the
surrounding pavement and sweep away all potential materials that may cause Foreign Object
Damage (FOD). Clean, lubricate, and properly store all equipment until the next repair operation.