Assessing Sustainability What Is Sustainability? In 1987, the World Commission on Environment and Development defined sustainability as a “development concept that meets the needs of the present without compromising the ability of future generations to meet their own needs.” Known as the “triple-bottom line,” sustainability is a system that encompasses three major components: economy, environment, and society. As a result of this decision, transportation agencies increased consideration of sustainability principles and practices to meet public demand. The economic component has been the dominant determining factor for transportation-related industries; however, the environmental and social components have grown in significance in recent years despite the limitations associated with their measurement and assessment. Sustainability is now a critical concern in modern pavement design. A sustainable pavement achieves its intended purpose while minimizing its environmental and societal impact. It is designed to meet engineering goals such as durability, safety, and performance while ensuring that basic human needs are met, resources are used efficiently, and surrounding ecosystems are preserved or restored. Pavement sustainability can be better understood when applied to the six phases of a pavement’s life cycle: production of materials, pavement design, construction, use, maintenance and preservation, and end life. With the ultimate goal of improving pavement sustainability over its life cycle, transportation professionals face numerous challenges regarding pavement materials decisions. These challenges include long-lasting materials used to offset higher costs and potentially higher production- related and transportation-related impacts. They also include using particular materials that may increase the frequency of required repairs because of high variability in projected performance. Further, some specifications already restrict the use of “lower impact” materials, which may prevent the opportunity to support and improve sustainability. Both economic and environmental perspectives must be accommodated when considering the sustainability of asphalt materials and mixtures. Numerous objectives currently exist for improving pavement sustainability with asphalt materials production. These objectives mainly focus on reducing the use of raw materials in terms of virgin binder and virgin aggregate in asphalt mixtures. This could be achieved using greater quantities of recycled materials such as reclaimed asphalt pavement (RAP); wastes such as rubber, plastics, etc.; bio-binders; and modified binders. Other objectives focus on reducing the energy consumed and emissions generated to produce asphalt mixtures, extending the life of asphalt materials, and reducing the transportation of materials. Promoting Sustainability in Virginia Over the last several decades, the Virginia Department of Transportation (VDOT) has evaluated the use and performance of several technologies in asphalt mixtures that can help reduce environmental burdens from the transportation systems. For Jhony Habbouche, Ph.D., PE, Senior Research Scientist, Virginia Transportation Research Council Recycled PlasticWaste &High RAP Content — Sustainability is now a critical concern in modern pavement design. A sustainable pavement achieves its intended purpose while minimizing its environmental and societal impact. It is designed to meet engineering goals such as durability, safety, and performance while ensuring that basic human needs are met, resources are used efficiently, and surrounding ecosystems are preserved or restored. 10 SPRING/SUMMER 2023
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