Elastomeric Pad Expansion Joint Installation Best Practices

Elastomeric pad expansion joints are the simplest type of bridge expansion joint, but correct installation is still essential for achieving their design service life. The pad must be positioned correctly, the concrete must be properly prepared, and the pad must be adequately restrained to prevent displacement under traffic. Site preparation begins with verifying that the concrete substrate is sound, clean, and at the correct level. Any loose or deteriorated concrete must be removed and repaired before the pad is installed. The substrate surface must be roughened by grit blasting or mechanical scarification to provide adequate bond for the adhesive. Pad positioning requires careful measurement to ensure that the pad is centered on the joint gap and that the gap is set correctly for the installation temperature. The design gap at the installation temperature is calculated from the design movement range and the installation temperature relative to the mean temperature. A gap setting jig is used to maintain the correct gap during installation. Adhesive application follows the manufacturer's instructions for the specific adhesive system. The adhesive is applied to both the pad and the substrate, and the pad is pressed firmly into position. Excess adhesive must be removed before it cures. The adhesive must cure for the specified time before traffic is permitted on the joint. Restraint of the pad against lateral displacement is provided by anchor bolts or embedded steel plates. The restraint system must be designed to resist the lateral forces from traffic loading and thermal movement. Anchor bolts must be installed to the specified torque and verified with a calibrated torque wrench. Post-installation inspection verifies that the pad is correctly positioned, the gap is at the specified width, and the adhesive has cured correctly. Any defects must be corrected before the joint is opened to traffic. A photographic record of the completed installation should be made for future reference.