Sealing of Small Movement Bridge Expansion Joints-Phase 2: Field Demonstration and Monitoring

摘要

A silicone foam sealant was developed to provide an easy-to-use and economical joint sealant for small-movement bridge expansion joints. In studies reported in Phase 1, various laboratory tests were conducted to evaluate the performance of the sealant using concrete as the bonding substrate. In the present study (Phase 2), laboratory tests on the sealant were conducted using other substrates found in practice, including steel, asphalt, and polymer concrete. Tension, repair, oven-aged bonding, salt water immersion, freezethaw, and cure rate (modulus vs. time) tests were performed to determine the engineering/mechanical properties of the foam sealant. These tests were also performed on a commercially available silicone sealant for comparison. A method to produce the foam sealant in larger quantity for field application was successfully accomplished. A procedure was developed to apply the foam sealant into bridge expansion joints. This development consisted of determining the proper applicator tools, a step-by-step application process, and the rehearsal of the sealing of a prototype 7-ft long x 2-in wide joint in the laboratory prior to field installation. After successful laboratory experimentation, the newly developed foam sealant along with the commercially available sealant were installed in the expansion joints of four bridges, one each in Connecticut, New Hampshire, Rhode Island, and New York. Over the course of approximately 20 months, post-installation monitoring of the sealants was conducted at the bridge joints to evaluate of the physical condition of the applied sealants. Through the laboratory tests, field installation, and monitoring, it has been observed that the silicone foam sealant has the ability to bond to various substrate materials, can accommodate deformation typical of small-movement expansion joints in bridges, is easy to install, and has displayed durability over the course of approximately 20 months in the field environment. The silicone foam sealant has been seen to provide as good as or in several cases superior engineering/mechanical properties in laboratory testing and better resiliency and performance in the four bridge expansion joints during the field testing.