Integrated Structure and Materials Design for Sustainable Concrete Transportation Infrastructure
The development of new transportation infrastructure materials is often disconnected from design, construction, and system management. Problems originating from this separation have resulted in using high performance concretes in Colorado and California bridges since 2000, which proved to be highly durable in laboratory development but have exhibited poor durability since field deployment. Impacts associated with reduced infrastructure sustainability due to this disconnect between material developers and infrastructure engineers can be widespread and long lasting. To bridge this separation, a new integrated structure and materials design (ISMD) framework is presented which ranges from nanometer-scale materials development to kilometer-scale infrastructure system management. This framework is unique from previous design paradigms in two ways. First, strong engineering linkages connect material development, structural design, and system management, providing a comprehensive design platform across varying length scales. Stemming from this integration, sustainability concepts are introduced in all phases of design, construction, and management and evaluated through an LCA feedback loop. Links between infrastructure engineering processes and LCA are made through material compositions, innovative structural service life models, and system sustainability indicators. To demonstrate the potential impact of this feedback framework from infrastructure material development through system management, a unique cement-based material, engineered cementitious composite (ECC), is investigated for the specific purpose of improving bridge infrastructure sustainability. While many “green concretes” focus on incorporating industrial wastes, they often ignore the associated negative impacts of reduced material performance on infrastructure durability and overall life cycle performance. Using ISMD, green ECC has been designed to be 500 times more ductile than normal concrete. This is accomplished while using industrial wastes to replace 75% of virgin feedstock but remaining highly durable, thereby cutting bridge maintenance activities by 50% over a sixty year service life and resulting in significant reductions in material consumption and infrastructure user costs from traffic delays.