The background and development of the specialized equipment required for the proper preparation and installation of hot-applied joint sealants is reviewed. The need to use specially designed melter-applicators is embellished. Many of the disastrous field problems resulting from failure to use approved equipment, as well as the appropriate sealant, are discussed in detail. The evaluation of field preparation and application equipment for hot-applied joint fillers and sealants is set forth, from hand pots and so-called tar of roofers' kettles to agitation, recirculation, and extrusion systems of today's melter-applicators. The required specialized laboratory test equipment is also discussed as is the correlation of test results with respect to field installation temperature parameters. Attention is also given to the proper selection of different types of sealants by basic constituents for compatibility with pavement type and previously used sealants and fillers.

Sealing pavement joints is necessary to minimize seepage of surface water into the subgrade and to prevent pavement damage. Joint seals for airfield pavements assume an additional level of importance since debris that is harbored in these joints can be injested and may damage aircraft engines. The paper briefly reviews a design procedure that has been used by the U.S. Air Force and includes a typical design example.

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 historical development of using bearings in Ontario and the current design requirements contained in the Ontario Highway Bridge Design Code and the Ministry's bearing specifications are reviewed. Numerous instances of unsatisfactory bearing performance, especially of proprietary rotational and sliding bearings, are described. Examples are given of unsatisfactory performance resulting from poor bridge design practices, improper bearing design, poor manufacturing procedures, and incorrect installation. In all cases, the action that has been taken to prevent a recurrence of the deficient performance is presented. The basic philosophy in design is to use the minimum number of bearings consistent with the articulation of the structure. The severity of the service environment has been recognized with the result that a high degree of corrosion protection is specified and a provision made for bearing replacement. All bearings are required to have a capacity for rotation about all three axes, which means that rockers, rollers, sliding plates, and cylindrical bearings are no longer used. The paper also describes the contractual relationships involved in the supply of highway bridge bearings and concludes that while a performance specification and guarantee would be desirable, such an approach is not practical.

Since some national standards on bridge bearings have been issued and a certain level of knowledge seems to have consolidated, the time has come to prepare an ISO Standard. The most important elements that should be part of such an ISO Standard are listed. Contradictions between existing national standards should be clarified and eliminated. Outlived technology should not be part of an international standard while national standards still may specify such bearings for local reasons.