To seal or not to seal: the road to sustainability is oftentimes under construction Scott Eilken Co-Chair Seal/No Seal Group West Coxsackie, New York he performance of concrete pavements is highly dependent upon the design, construction and maintenance activities. During the project development stage, owners select pavement design features based on their ability to balance cost and performance to establish what they believe is the best value or design optimization. The best value may be different than the lowest initial construction cost and can differ based on the category and function of the roadway. The expected level of performance depends, among other things, upon the desired level of service, facility type, traffic levels, speeds, etc. An urban freeway typically requires a higher performance level than a city street for example. The owners of transportation facilities are faced with the challenge of balancing infrastructure needs with current and future budgets, designing for predicted future traffic levels, and
procurement of construction contracts through a competitive low-bid system. Many of these aspects make selecting the best value difficult to say the least. Today, economic pressures promote the use of least-cost construction techniques for new construction. Although at first blush these approaches may seem desirable, it is the long-term performance and true value of the design feature that should dictate their use. This is particularly true in markets where the construction commodities are escalating in cost at different inflation rates as has occurred in the U.S. for the last two decades. However, oftentimes inadequate experience or data is available to properly quantify the benefit of a given design feature. A case in point is the use of joint sealants in concrete pavements. Since joint sealants can add as much as 10 to 12 percent to the initial construction cost, their value
While constructing a four-lane roadway through an urban Joliet, Ill. area, diamond blade wet sawing was used to widen and wash the control joints prior to sealing.
68 APWA Reporter
May 2012
can only be determined if sufficient pavement life extension is derived as a result. However, this life extension has yet to be adequately defined. The use of joint sealants has been pervasive since the early 1900s and has been considered part and parcel with the construction of concrete pavements. In the early 1990s the value of joint sealing was challenged by the Wisconsin Department of Transportation and considerable differences in opinion have evolved since then. With the current economic times, it is even more difficult for owners to judiciously determine the true value of concrete joint sealants. A few examples follow which indicate the difficulty in making such a decision and why the road to sustainability is oftentimes under construction.
Sealant studies and research The most recent FHWA Study, “Effectiveness of Sealing Transverse Contraction Joints in Concrete Pavements,” August 2008, indicated that little benefit was obtained through the use of sealed joints. However, the average age of the pavements investigated was less than ten years, so this study only evaluated the performance of early age concrete pavement. As mentioned, the value of any design feature must be determined from its impact on the long-term performance. The study results were further constrained in the fact that it dealt primarily with doweled pavements located in the wet freeze environment. The current AASHTO Mechanistic Empirical Pavement Design Guide
