Concrete Nosing Expansion Joint Waterproofing Detail at Deck Level

The interface between the concrete nosing expansion joint and the bridge deck waterproofing membrane is a critical detail that must be designed and constructed carefully to prevent water infiltration. Water at this interface can cause corrosion of the reinforcement and deterioration of the bridge structure. The waterproofing membrane must be terminated at the steel edge angle of the nosing joint and sealed to prevent water infiltration. The termination detail must accommodate the movement of the joint without tearing the membrane. A flexible flashing strip bonded to both the membrane and the edge angle provides a watertight connection that can accommodate movement. Flashing strip material must be compatible with both the waterproofing membrane and the edge angle coating. Bituminous flashing strips are compatible with bituminous membranes but may not be compatible with polyurethane membranes. EPDM flashing strips are compatible with most membrane types and provide good flexibility and durability. Bond between the flashing strip and the edge angle requires a primer compatible with the edge angle coating. The primer must be applied to the clean, dry surface of the edge angle and allowed to dry before the flashing strip is applied. The flashing strip must be pressed firmly onto the primed surface to ensure full contact and bond. Overlap between the flashing strip and the waterproofing membrane must be sufficient to provide a watertight seal. A minimum overlap of 100 mm is typically required. The overlap must be bonded with the appropriate adhesive and pressed firmly to ensure full contact. Quality control of the waterproofing detail requires inspection of the flashing strip installation before the wearing course is applied. The flashing strip must be inspected for correct adhesion, correct overlap, and absence of voids or bubbles. A water test should be performed to verify waterproofing before the wearing course is applied.