Bridge Expansion Joint for Bridges with Expansion Joints in Deck Membranes

Bridge deck waterproofing membranes must be carefully integrated with expansion joints to ensure continuous waterproofing across the joint location. The integration detail must accommodate the movement of the joint while maintaining the waterproofing function throughout the design life. Membrane types used for bridge deck waterproofing include sheet membranes (modified bitumen, EPDM, TPO) and liquid-applied membranes (polyurethane, epoxy, acrylic). Each membrane type has different properties that affect the integration detail at the expansion joint. Sheet membrane integration at expansion joints requires a flexible flashing strip that bridges the joint gap. The flashing strip is bonded to the deck membrane on both sides of the joint and must be long enough to accommodate the full movement range. The flashing strip material must be compatible with the deck membrane and must have adequate flexibility for the movement range. Liquid-applied membrane integration at expansion joints requires a flexible reinforcing fabric embedded in the membrane at the joint location. The fabric bridges the joint gap and reinforces the membrane against the stress from the joint movement. The fabric must be long enough to accommodate the full movement range without being pulled taut. Membrane termination at the edge beam must be sealed to prevent water infiltration at the membrane-edge beam interface. A compatible sealant is applied at the termination to provide waterproofing. The sealant must be flexible enough to accommodate the movement of the joint without cracking. Quality control for membrane-joint integration requires inspection of the flashing strip or reinforcing fabric installation, the membrane termination, and the sealant application. Any defects in the integration detail must be repaired before the wearing surface is applied. A flood test can be performed to verify the waterproofing performance of the completed installation.