International Concrete Abstracts Portal

SP-164 (V2) Although bearing and joint systems comprise only a small percentage of the construction cost of highways, buildings, and bridges (1 percent, typically), their importance to the functioning of those structures is vastly greater. For without adequate engineering effort in design of these vital elements to account for the many, sometimes conflicting, requirements of loading and/or movement, the integrity of the entire structure may be compromised. Our increased understanding of seismic activity has made us more aware of the wider area of this activity as the greater demand placed on support and joint systems. This Fourth (quinquennial) World Congress on Joint Sealing and Bearing Systems in Concrete Structures will enhance the general understanding of these systems and introduce entirely new concepts developed to cater to the latest seismic code requirements. As with the first two Congresses, this is V.2 of a two-volume set. V.1 contains 22 papers, plus the abstracts ofpapers presented at the Third Congress.

The aim of the study was to understand the behaviour of bituminous joint sealants during installation using Infra-red thermography in combination with supplemental studies using Dynamic Shear Rheometer (DSR) and High Performance-Gel Permeation Chromatography (HP-GPC). Using IR thermography, in-situ temperature measurement of a joint sealant product was carried out. To evaluate the change in the rheological properties of the product after the installation, due to aging, DSR testing was made for both a fresh and an installed sample. Chemical analysis using HP-GPC was also carried out to see the difference in the state of the polymer used as modifier in the product. The results ensured the suitability of IR thermography for non-destructive quality control during installation of bituminous joint sealants. Overheating of polymer-modified bituminous binders during the installation must be avoided to prevent thermal aging of the polymer. In case the deterioration of the polymer takes place, the binder will act less viscoelastic in practice. Physical and chemical changes in bituminous joint sealants, which have taken place during the installation due to aging, can be well understood by combining IR thermography with the laboratory tests, such as DSR testing and HP-GPC.

A suitable design of deck joints and bearings in highway bridges should take into account the environmental conditions existing in the location of the bridge. Several authors state that the influence of the thermal effects should never be un derestimated in the design of joints and bearing systems and point out the existence of damages-in bridges due to environmental thermal effects. This paper presents a general method for the prediction of thermal movements in highway bridges located in Spain. It provides design recommendations which allow accurate prediction of thermal movements, depending on the location of the bridge, the longitudinal type of the bridge deck, the cross section type and other factors which significantly affect the thermal response of the bridge. Lastly, the influence of the temperature of settlement of the deck joints is also considered, in order to determine precisely the thermal movements in highway bridges. Such method can be developed and applied to other countries.

The design of a bridge deck joint must be able to withstand the wear and impact of heavy traffic loads, and resistant to roadway oils and chemicals, debris, ultraviolet rays, and other environmental factors. Failure of a joint system can occur from a debonding of the nosing and substrate; a delamination of material layers; severe wearing, cracking or spalling of the nosing; or improper aterial mixing and joint installation. Loose steel armor retainers and leaking joint seals also cause joint system failures. A large scale accelerated testing facility designed and constructed at the University of Central Florida has tested over twenty different bridge deck joints for wear, abrasion, impact loading, and leakage. Many of the aforementioned failure criteria were observed during the course of testing. The testing program also established a simulated life expectancy for each joint system as a result of its performance under full-scale live loading, during a five week test period. This method of testing proved to be a timely, feasible alternative to live bridge applications and monitoring procedures. Test results indicated several areas of deficiency common to many of the joint components and systems and promoted further development of some of these products to enhance their performance.

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.