Satisfactory performance of non-composite box-beam bridges depends on the effectiveness of the key way, waterproofing membrane and tie rods, and the related construction practices. Development of cracks at the longitudinal joints of such bridges is often a recurring problem that causes water leakage at the joints and corrosion of the embedded prestressing strands. The primary objective of this study was to identify the sources, causes and effects of inadequate waterproofing at the joints and to develop prevention measures. The performance of waterproofing membranes and the structural performance of key way joints with the existing and new grout materials were evaluated and correlated with field measurements recorded under traffic loading. Construction practices for new bridges, and the investigation of a bridge that was in service for 32 years at the time of its demolition were also documented. Mechanical tests on membranes revealed that they are able to accommodate at least one inch of tensile and shear deformations without losing their waterproofing properties. That kind of elongation allows membranes to bridge over any cracks that may develop at the longitudinal joints. Therefore, membrane deficiencies may not the primary cause of water leakage. Key way joints with a combination of the currently specified ODOT geometry and ODOT-approved grouts were found to be incapable of carrying any shear loads in conjunction with out-of-plane moments. From the limited site inspections done in this project, the practices followed at construction sites seem to be seriously flawed and may be largely contributing to water leakage problems in box-beam bridges. Recommendations on new key way geometries and the grouts that were developed and tested in this project are suggested for implementation.

At head of title: National Cooperative Highway Research Program.

Bridge designs frequently employ precast concrete box beams, with adjacent beams connected using grouted keyways. Failure at these joints leads to water leakage and corrosion in reinforcing bars/strands, resulting in severe damage to concrete elements and reducing the bridge's lifespan. This dissertation investigates the causes for the ineffectiveness of waterproofing membranes in preventing leakage at joints of adjacent box beams.Testing of five commercially available waterproofing membranes showed low tensile and shear strength and high deformability, with membranes exhibiting large elongation and no leakage. Adhesion tests showed limited peel strength. Different practices such as use of primer, sealant, and direct heat were also investigated. Sealant provided better bonding than primer, and heating yielded no improvement in bond strength. All membranes showed low punching resistance but could resist loads up to 1,200 lb in wheel load tests without being damaged. Prestress losses were calculated for construction scenarios for concrete box beams of ages varying from 7 to 180 days at time of deck placement. The difference in prestress losses have an inverse relationship with concrete age at the time of deck placement, while an inverse relationship exists between the age of concrete of prestressed box beams at the time of deck placement and the differential deflections. Spans having different lengths were found to have a proportional relationship to the difference in prestress losses and differential deflections. While differential prestress losses at different concrete ages contribute to joint cracks between adjacent box beams, losses may not be sufficient to rupture the membranes. The maximum differential deflection between adjacent box beams with different concrete ages may cause cracking in the keyways but is likely to be negligible compared to the ability of the membrane to stretch. In visits to an existing bridge and a new bridge underconstruction, deficiencies were noted in the implementation of waterproofing membranes: inadequate specifications and ineffective inspection, absence of membranes on portions of the existing bridge, and protrusions/debris on the concrete deck of the new bridge prior to membrane installation. This study recommends that waterproofing membranes continue to be used in bridges and provides suggestions to improve their implementation.

Worldwide, integral type bridges are being used in greater numbersin lieu of jointed bridges because of their structural simplicity,first-cost economy, and outstanding durability. In the UK and theUS states of Tennessee and Missouri, for example, the constructionof most moderate length bridges is based on the integral bridgeconcept. The state of Washington uses semi-integral bridges almostexclusively, while, depending on subfoundation characteristics, thestate of Ohio and others use a mix of these two bridge types. Integral and Semi-Integral Bridges has been written by apracticing bridge design engineer who has spent his entire careerinvolved in the origination, evaluation and design of such bridgesin the USA, where they have been in use since the late1930’s. This work shows how the analytical complexity due tothe elimination of movable joints can be minimized to negligiblelevels so that most moderate length bridges can be easily andquickly modified or replaced with either integral or semi-integralbridges. Bridge design, construction, and maintenance engineers; bridgedesign administrators; graduate level engineering students andstructural research professionals will all find this bookexceptionally informative for a wide range of highway bridgeapplications.

This synthesis will be of interest to bridge designers, maintenance engineers, and others concerned with designing and maintaining bridge deck joints. Information is presented on the types of deck joints used in bridges and on the design of bridges without joints. Bridges are continually moving and thus need either some type of deck joint or an integral design to accommodate this movement. This report of the Transportation Research Board describes the types of deck joints being used, the problems with these joints, and how integral construction-- bridge decks without joints--can be used to avoid joints.