Concrete Infrastructure Sustainability: Life-Cycle Metrics Material Design and Optimized Distribution of Cement Production
Cement production is the second most carbon dioxide intensive industry, accounting for 5% of anthropogenic emissions. As the key binding agent in concrete it is integral to the modern infrastructure our society depends on. The U.S. invests more than 260 megatonnes of concrete at a cost of nearly $65 billion annually in its road and highway infrastructure alone. Despite this, road and highway infrastructure remains in poor condition. A new approach to how cement materials are used and produced is needed to improve its sustainability.
This dissertation develops methods for quantifying and characterizing the sustainability of different options in cement production and its use in concrete infrastructure applications. Four methods are presented, (1) life cycle modeling of concrete infrastructure comparing new designs and engineered cementitious composite (ECC) materials to conventional designs and materials, (2) life cycle modeling applied to the development of greener ECC materials, (3) overlay analysis of constraints on mineral resource extraction to assesses the feasibility of siting large consolidated cement plants and quarries, or "megaquarries," and (4) network analysis of freight transportation to quantify energy and cost implications of megaquarries.
Life cycle modeling showed adopting a novel design for the concrete bridge deck using an ECC link slab design improved environmental and cost performance. The modeled deck experienced high traffic flow, and the novel design showed a 40% improvement in sustainability indicators, with traffic-related impacts dominating results. Life cycle modeling was extended to enhance the sustainability performance of ECC materials used as link slabs. Results showed the key driver for material performance is sufficient durability, and alternative constituent materials perceived as environmentally friendly should only be used if ECC durability meets infrastructure design needs. Overlay analysis showed constraints on limestone extraction, cement's primary raw material, eliminated access to 15%-39% of resources in the Great Lakes region. Despite this, sufficient limestone resources exist for large cement operations. Once the feasibility of megaquarry development was established, network analysis was applied to the freight distribution network used for cement delivery showing that a megaquarry is far less efficient at supplying the region compared to the existing decentralized production strategy.
Kendall, Alissa. 2007. Concrete Infrastructure Sustainability: Life Cycle Metrics, Materials Design, and Optimized Distribution of Cement Production. Doctoral Dissertation, University of Michigan, Ann Arbor: 1- 162.