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The purpose of this research effort was to develop a realistic material specification closely related to the actual field performance of sealers. It succeeded in developing a method for testing the life expectancy of subject sealers by measuring the loss of sealer resiliency due to continuous simulated bridge end movements induced by actual environmental changes. Data gathered through such testing has established that the quality of preformed sealers is significantly nonuniform. This deficiency is believed to be a consequence of a general lack of sufficient uniformity in the production of synthetic rubber products. As a result of these and numerous other laboratory tests, it was determined that the current sealer specification, although having served to insure product quality on many occasions, evidently has failed in a significant number of instances to identify a sealer's total inadequacy for its intended purpose. However, the research indicated that, except for the addition of the compression set test and an upgrading of the minimum pressure requirement, most physical requirements in the subject specification cannot be improved. Unfortunately, the ultimate solution to the critical problem of identifying adequate sealers for bridge decks remains essentially unestablished. The task of quality assurance, therefore, still rests for the most part with the sealer manufacturers and their rubber specialists.

A performance specification, although an unconventional approach, can be an effective way to insure that only high quality bridge deck joint sealing systems are designed and selected for use. History of the past decade, when these systems were first used to seal the gap between moving bridge ends, has shown that the systems have not always been as durable as they need be to fulfill their intended function over the life span of the bridge. Disappointing results can be attributed in part to the relative newness of their application and unfamiliarity of the producers with the demands of the task. More importantly, short-comings can be traced to a selection procedure which relies mainly upon low initial cost rather than quality. Without the application of uniform standards by which to measure performance, there can be no means to judge the relative merits of candidate systems. A well-designed performance specification can meet this need. Although it would be desirable to force producers to guarantee their system's quality over the long term, the concept is contractually and practically untenable. A specification embodying performance criteria for products to comply with prior to, and just after installation, can go a long way to insure that only systems having a good chance of success are selected.

The paper describes the requirements which were developed for deck joints for the Ontario Highway Bridge Design Code. The Code provisions apply to prefabricated joint assemblies which accommodate translation and/or rotation. The basic philosophy of the Code is that the minimum number of joints be used consistent with the need for articulation and drainage of the structure. Sources of movement and loads on deck joints are discussed in detail. Two types of joint are recognized: those which are sealed against penetration by water and open joints in which the flow of surface drainage is permitted. Requirements for each type of joint are given. Requirements for durability, skid resistance, attrition, noise, ease of inspection, maintenance and modification are expressed qualitatively. Requirements for installation, permissible gaps and anchorage are expressed quantitatively. Factors influencing the selection of the type of joint are given.

The generic class of silicone sealants include some unique variations that are particularly suited for sealing concrete structures. These are the varieties which have neutral cures, very low modulus and high elongation. There are also types of silicone sealants that should not be used on concrete. Specifically, these are the types which are generally classified as the acid cures. There are special applications like prolonged total submergence on concrete where no silicone should be used without special precautions. There are also joint design considerations which may lead to a choice of one sealant over another. Thus, selecting the appropriate silicone sealant for the application is fundamental to a successful seal and many factors go into that decision. Equally fundamental is the proper installation technique. Cleaning is always required on concrete. The cleaning technique will vary dependent on whether it is new construction or re-seal and most important whether it's raw concrete or if the concrete is coated or contaminated. Other installation considerations include backing materials and tooling techniques. Lastly, a proper installation includes post installation inspection and testing.

Most of the joint sealant and waterproofing contractors throughout North America have experienced a considerable amount of costly rework and legal difficulties as a result of wholesale failures of field molded sealants. As a direct result of this, the principal joint sealing contractors in U.S.A. and Canada formed an association in 1976 whose principal goals are to protect themselves from legal complications arising out of failed sealants and to take direct action by maintaining a forum of experts that will educate architects, owners, contractors, sealant manufacturers and the public in general regarding the true limitations and capabilities of sealants. A set of guide specifications will shortly be issued by the Sealant & Waterproofers Institute as a fundamental step in this educational process.