Evaluation of the Installation and Initial Condition of Rosphalt Overlays on Bridge Decks

About the report:

Protection systems are placed on bridge decks to retard the intrusion of chlorides and moisture that can eventually cause corrosion deterioration. The Virginia Department of Transportation typically uses hydraulic cement concrete (HCC) overlays of latex-modified concrete (LMC); LMC with very early hardening cement (LMC-VE); and silica fume concrete (SFC) and epoxy overlays for deck protection. Occasionally, a conventional asphalt overlay and waterproof membrane system is used.

Rosphalt is an asphalt that is considered to be impermeable and has been used on decks without placement of a membrane. The purpose of this research was to evaluate the construction, initial condition, and cost of the Rosphalt overlays placed on two bridges in Virginia: (1) the northbound lanes of I-85 over Route 629 and the eastbound and westbound lanes of Span 22 of the Norris Bridge on State Route 3 over the Rappahannock River. As a comparison to Rosphalt, a conventional asphalt overlay and waterproof membrane system was placed on the adjacent bridge on the southbound lanes of I-85 over Route 629. Emphasis was placed on comparing the wearing and protection systems with respect to speed and ease of construction (including lane closure time), initial condition as indicated by physical properties, protection and skid resistance, and cost. An objective was also to compare these asphalt protection systems to HCC overlays of LMC-VE, LMC, and SFC and epoxy overlays.

Costs varied greatly depending on the estimates used and the bid prices. Although estimates for the Norris Bridge indicated Rosphalt as the lowest cost option, bid prices showed it was likely the most expensive option. Three overlay options, Rosphalt, SM-9.5 mixture and membrane, and LMC-VE, are rapid and can provide major reductions in traffic control and user costs. Based on laboratory tests, Rosphalt is more fatigue and rut resistant than the SM-9.5 mixture and should last longer but based on the cost of the first two installations in Virginia, Rosphalt is too expensive to be considered as a competitive overlay system.

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