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In Denmark, all important concrete bridges are waterproofed and asphalt paved. Joints in bridge surfacing are important details as leakage often starts along the edges and the expansion devices. Practice has shown that with a proper sealant, joint leakage is much more apt to occur between the sealant and the joint sides than due to a break in the sealant. A low elastic modulus of the sealant will reduce the tension between the sealant and the joint sides and is consequently an important property. A suitable primer should always be used, and the shape factor of the joint should be restricted to about 1:1. The present Danish specifications for joint sealants and primers are quoted and discussed. Important details of the workmanship are also specified. Measurements of typical movements in bridge surfacings are reported. Research concerning new specifications is presented. An elaborate device for testing the deformation properties of joint sealants at different temperatures down to -20 C has been constructed. It is intended to use the device to study the influence of such characteristics as aging, water, alkali, and joint geometry. It is expected that the investigation will result in new and more relevant specifications and easier control procedures. The research is directed toward bridge joints, but the results are applicable to joints in concrete roads as well.

The concrete girder for the Pasco-Kennewick Intercity Bridge is continuous (i.e., without intermediate expansion joints) for its entire 2500-ft (762-m) length. Nearly 1800 ft (549 m) of this girder is suspended entirely from towers by stay cables. The remaining portions are supported on sliding disk bearings. The girder is fixed at only one end; all expansion and contraction occurs at the opposite end, requiring an expansion joint with a 26-in. (660-mm) movement capability--the largest of any as of the time it was installed (1978). To control permanent deformations and thereby minimize the size of bearings and joints, the designer called for: (1) the girder to be precast in segments; (2) a minimum 28-day compressive strength of 6000 psi (41 MPa); (3) special requirements for curing the segments; and (4) the segments to be stored for at least 90 days prior to erecting them. The sequence of construction complicated the installation of the bearings. The bridge was built in stages with each stage having a different temporary fixed bearing. Thus, the setting (offset) of each bearing had to provide for the permanent deformations that the partial-length girder would undergo before being incorporated into the final structure, as well as for the predicted temperature at that later date. Following seven years of service, the deformations in the girder and movements in the bearings and joints have been within the limits assumed in their design. All components are performing fully as intended.

In the United Kingdom normal gap-graded dense bituminous surfacing is usually laid on bridge decks. At the expansion gap, below pavement (buried) joints have been widely used to provide a smooth and continuous running surface and for ease of resurfacing. On all-concrete structures this type of joint has been used successfully but on steel/concrete composite decks there have been premature failures, particularly when there is a large volume of commercial vehicles. A survey and field trials investigated the factors influencing the performance and the requirements for buried joints. Measurements established that dynamic traffic loading produced movements and rotations at the expansion gap that were detrimental to the performance of buried joints, particularly on composite structures. It was also found that restraints at the bearings lower the centre of rotation and so increased the joint opening. The survey showed that only limited improvements in joint performance could be obtained from modifications to the design. Trials were therefore made on a 600m length of motorway viaduct with modified surfacings. It was found that a rubberised bitumen and a high penetration bitumen both showed a substantial improvement compared with normal bitumen. Delays caused one carriageway of the trial to be laid in cold, wet and frosty conditions and the subsequent performance was very inferior to the carriageway laid in dry warm weather. Workmanship and weather during laying both have a major effect on the behaviour of the joint. Alternative types of joint with flexible surfacing materials which are able to absorb all joint movements gave a good performance where conventional buried joints have proved unsatisfactory

SP70 The proceedings of the World Congress on Joint Sealing and Bearing Systems for Concrete Structures reports on new developments and case histories. General subjects include: movements and forces, bearings, joints, materials, architectural applications, seismic considerations, pavements, and research and development.

Graphical procedures are presented for optimum dimensioning of a joint-slab-sealant system coupled with material properties. PART 1 covers an approach for sealing with compression type sealants while PART 2 concentrates on molded-in-place sealants. Horizontal joint movements are emphasized in both cases. While the main emphasis is placed on concrete pavement joint sealing, the methods are also applicable to other joints, such as those in bridges or structures and even cracks. The procedures used to construct each set of curves are given so that the graphs can be adjusted for other joint or crack sealing applications. The paper also outlines areas where more work and data are needed.