Discovering Institutional Barriers and Opportunities for Sustainable Concrete Construction

Abstract

Abstract Using industry standards to commodify cement beginning in 1904, the cement and concrete industry surrendered control of their product to the market and the concrete industry as a whole developed a technocratic and conservative culture. Both industry standards and the culture which they have created have had lasting impacts on the industry with respect to innovation and potentially more sustainable concrete construction. Industry standards and project specifications have institutionalized concrete optimized for high early strength and rapid construction rather than durability. The objective of this research is to identify specific points at which industry standards can limit innovation and more sustainable concrete construction and then demonstrate the benefits of concrete optimized for durability. This thesis was tested using social networking tools to inform case study analysis. Networking results generated a ranking of the most central U.S. industry standards related to concrete bridge construction, providing a framework for case study analysis. The highest ranked standards, American Society for Testing and Materials (ASTM) C 150 “Standard Specification for Portland Cement” and American Concrete Institute (ACI) 211.1 “Standard Practice for Proportioning Normal, Heavyweight, and Mass Concrete,” were then evaluated using sustainability metrics. These documents do not explicitly limit innovation or more sustainable construction, but it is the way these documents are used that impacts sustainable concrete construction. C 150 itself does not inhibit more sustainable material, but the way in which it is used by architects and engineers to garner high early strength renders concrete with heavier environmental impacts than necessary. Even though ACI 211.1 is not a legally binding document, it has established the status quo for proportioning concrete for high early strength. The industry has evolved under pressure to optimize for high early strength at the cost of durability. Industry standardization has developed a conservative culture, but it is actually the individual project specifications rather than industry standards that explicitly inhibit sustainable concrete construction. This study also demonstrates the benefits of optimizing for durability. Designing a durable concrete using well-graded aggregates and performance-based specifications significantly reduced cement paste requirements in nearly all cases, which showed reduced material impact of fresh mixes. Durability projections augmented the sustainability benefits dramatically. Well-graded mix designs with 6% air entrainment categorically showed longer service lives and reduced annual material impact compared to their gap graded counterparts. Mixes designed using National Ready-Mixed Concrete Association model performance based specifications similarly demonstrated drastic environmental and durability improvements.