The six papers in this Symposium Publication address many different aspects of mechanistic design, such as environmental stress, improved pavement design methodology, approaches to performance-based specification, characterization of joint sealants for design purposes, characterization of concrete strength based on fracture properties, and others. Note: The individual papers are also available as .pdf downloads.. Please click on the following link to view the papers available, or call 248.848.3800 to order. SP181

This paper develops a finite-deformation viscoelastic material model to characterize the behavior of a silicone-based sealant material. A series of relaxation tests were performed on the test specimens for different levels of age and unit extension. Based on the experimental results, a master relaxation modulus curve is constructed. Unit extension and age effects are incorporated in the master relaxation curve by using the superposition principle. The shift factor equations developed were based on the relationship first suggested by William, Landel and Ferry (WLF Equation) and traditionally used for incorporating temperature effect. The unit extension and age dependence are accounted in the “reduced time”. The material model derived is of the generalized Maxwell (in parallel) type, which is simple and can be easily applied in finite element programs for stress analysis of joint sealants in concrete pavement.

This four-year project was carried out in an aim to conduct a mid- to long-term, large-scale study on selected field-moulded sealants in concrete joints at different hydraulic structures under extremely cold climatic conditions. Other objectives were to specify installation techniques, carry out periodic inspections, evaluate the performance of various types of such sealants that could be of value to all potential users. The project also included a cost effectiveness study. General and specific guidelines were prepared for sealant selection and their installation. Based on these guidelines, different types of sealants, polyurethanes, polysulphides, silicone (1- and 2-component), were selected for the study. They were installed in horizontal, vertical and inclined joints at different locations on five Hydro-Quebec dams, mostly on the crest, and were periodically inspected for their performance. The findings are presented in this paper.

From shortly before the entry of the U. S. in World War II and to the present, the author has been continuously involved in the design, testing, manufacturing, and observation of the performance of joints of all types, from pavements to bridges, and bearings of all types, from the old rockers to elastomeric, pot, disc, and then to earthquake isolation concepts. Starting out with load transfer devices buried in concrete pavement joints for state highways and airfield pavements to field molded sealants and then compression seals, the design trend in pavements has been from longer 100 ft panels (30 m) to relatively short panels of 15 ft (4.5 m). This has greatly simplified the sealing problem, since the distance changes between joint interfaces of shorter length panels obviously are much less in creep-shrink and thermal volume change. With respect to bridges, the design trend has been reversed, going from relatively short decks of 40 ft (12 m) to longer and longer spans, greatly complicating the sealing problem. It was in this confused design period that the writer worked toward developing sealing and bearing systems for every conceivable type pavement or bridge structure. Some lessons learned during the past 50 or more years are the subject of this paper.

To assist bridge engineers in the State of Florida in selecting expansion joint systems, the Florida Department of Transportation/Structural Research Center (FDOT/SRC) concluded a two year bridge expansion joint evaluation program. This program consists of three components: I) Performance Evaluation, 2) Load Test Evaluation, and 3) Installation & Maintenance Evaluation. The test elements include seals. compression seal joints, strip seal joints, and buried joint systems. Twelve (12) joint suppliers volunteered to participate in the program. A total of seventeen (17) joints (or seals) were installed in eight (8) bridges on I-95 in Saint Lucie County, District IV. All bridges in the test program have prestressed concrete AASHTO girders and concrete deck slabs. All the bridges had armored compression seals at the end bents. In general, the test joint systems or seals were installed at the end bent joints (replacing the original material). The original design joint opening at 70 "F was one inch (1") for the end bent joints. Using criteria recommended by FDOT engineers and the Structures Design Guidelines, the SRC evaluated the test expansion joint sealants or systems. This paper presents the results of the test program. Also, it provides guidance concerning the selection of expansion joint systems for both new and existing bridges.