Wet-Reflective Pavement Marking Demonstration Project, November 2011

One of the leading complaints from drivers is the inability to see pavement markings under wet night conditions. This issue is a major source of dissatisfaction in state department of transportation (DOT) customer satisfaction surveys. Driving under wet night conditions is stressful and fatiguing for all drivers, but particularly so for the more vulnerable young and older driver age groups. This project focused on the development of a two-year, long-line test deck to allow for the evaluation and demonstration of a variety of wet-reflective pavement marking materials and treatments under wet night conditions. Having the opportunity to document the performance of these various products and treatments will assist the Iowa DOT and local agencies in determining when and where the use of these products might be most effective. Performance parameters included durability, presence, retroreflectivity, and wet night visibility. The test sections were located within Story County so that Iowa DOT management and staff, as well as local agencies, could drive these areas and provide input on the products and treatments.

Low Profile Marker for Wet/Night Visibility, HR-1005, 1977

Conventional highway lane markings are ineffective at night, particularly when the pavement is wet. There is a recognized need for a system that is effective at night under wet conditions and where there is no reduction in current daytime standards. To be effective at all times the system must maintain wet-night retroreflective properties while resisting deterioration caused by snowplows, studded tires, sand and salt applications, and lane changing maneuvers by traffic. This project tested a system of low-profile lane markers developed by Battelle Columbus Laboratory under contract with the Implementation Division of the Federal Highway Administration.

The Utilization of Agriculturally Derived Lignin as an Antioxidant in Asphalt Binder, TR-557, 2008

Oxidation is the primary cause of long-term aging in asphalt pavements. As a pavement oxidizes, it stiffens and can eventually crack. The use of an antioxidant as a performance enhancer in an asphalt binder could delay aging, thus increasing the life of an asphalt pavement. Lignin is a highly available and well-studied antioxidant. A wet-mill ethanol plant produces several co-products, some of which contain lignin. The use of lignin from ethanol production could provide a benefit to asphalt pavements and also give more value to the co-products. The following research examined the effects of lignin on asphalt pavements. Three lignin-containing co-products were separately combined with four asphalt binders in varying amounts to determine the optimum amount of co-product that would provide the greatest benefit to the asphalt binders. The asphalt binder and co-product blends were evaluated according to Superpave specifications and performance graded on a continuous scale. The data indicated a stiffening effect on the binder caused by the addition of the co-products. The more a co-product was added, the more a binder stiffened. Binder stiffening benefited the high temperature properties and the low temperature binder properties were negatively affected. However, the low temperature stiffening effects were small and in many cases not significant. The co-products had an overall effect of widening the temperature range of the binders. This result suggests some antioxidant activity between the binder and the lignin. Testing with a fourth co-product with no lignin supported the idea that lignin acts as an antioxidant. The samples with no lignin aged significantly more than the samples with lignin. Infrared spectrometry also supported the idea that lignin acts as an antioxidant by observing decreases in some oxidative aging products.