Steven M. Soltesz

Corrosion prevention and remediation strategies for reinforced concrete coastal bridges

Abstract Oregons coastal highway includes over 120 bridges, most of which are reinforced concrete bridges. Twelve are historic structures. Over 40,000 m 2 of bridge surface has been repaired and is protected from further corrosion damage using thermal-sprayed zinc anodes in impressed current and galvanic cathodic protection (CP) systems. In addition, thermal-sprayed titanium, thermal-sprayed Al–12Zn–0.2In, and zinc-hydrogel anodes are being evaluated in demonstration projects on coastal bridges. Thermal-sprayed zinc anodes are estimated to have a service life exceeding 25 yr but exhibit increasing anode polarization with electrochemical age. Humectants such as lithium nitrate and lithium bromide can reduce anode polarization and extend anode service life. Catalyzed thermal-sprayed titanium anodes develop no significant anode polarization and exhibit stable long-term performance. Zinc-hydrogel galvanic anodes produce a stable protection current with no evidence of aging effects. One of the more powerful and economical tools available for assessing potential corrosion problems in a structure and for characterizing the corrosivity of bridge microclimates is chloride profiling. Current Oregon DOT specifications call for the use of stainless steel reinforcing bar in deck, beams, and precast prestressed girders, and of microsilica concrete in all future coastal bridge construction. Stainless steel bar adds a 10% premium to total project cost compared to black iron bar but is expected to reduce cumulative costs by 50% over the 120+ yr bridge life.

Fiber grating traffic monitoring systems

Previous studies have shown the capability of fiber Bragg gratings (FBGs) to monitor components of strain on bridges and structures. In past months, Blue Road Research and the Oregon Department of Transportation embedded long-gage FBG sensors into the Interstate 84 freeway east of Portland, Oregon to determine the feasibility of retro-install and for use of these sensors in monitoring freeway traffic speeds under conditions similar to loop inductors, piezo-ceramic weigh-in-motion (WIM) systems, and other vehicle monitoring devices. The objective of the study was to develop a working traffic sensor system with the potential to be more durable, reliable, informative, and cost-effective than currently available traffic sensors. A primary purpose of the freeway installation was to test the sensors for vehicle classifier and counter applications. In addition to discussion of the advantages of using FBGs for traffic classifiers and systems over conventional sensing methods, this paper overviews the installation and summarizes the use of FBG traffic sensors for vehicle counting and classification.

Fiber grating systems for traffic monitoring

Blue Road Research has designed, built, and installed fiber grating sensor systems onto bridges, and most recently into an asphalt and concrete highway test pad. The sensitivity levels of the fiber grating sensors are sufficiently high to enable detection of people standing on the bridge or highway. This paper briefly overviews the usage of these sensors for traffic monitoring.

Development and deployment of fiber optic highway and bridge monitoring sensor systems

Fiber grating strain sensors offer a means to monitor the health of highways and bridges as well as a means to monitor vehicular traffic patterns and critical data such as speed, weight, and classification of vehicle types. This paper overviews recent results associated with employing very high speed demodulation systems with capabilities in excess of 10 kHz and strain sensitivities on the order of one microstrain. It is clearly shown that this type of system can be used as an effective traffic monitoring tool as well as for health monitoring purposes.