Long lasting, sustainable structures require durable and resilient materials and for many dam applications concrete is the material of choice. Cement and concrete are central to the economic viability and resilience of dam and water resource projects. Concrete materials are selected for the long service life they provide, which can be readily demonstrated with a life cycle analysis (LCA). The initial carbon footprint of any material or construction method is an important aspect of an LCA, but may not have the greatest contribution: maintenance considerations and overall service life often ultimately outweigh the initial footprint.
Portland cement (PC) has been the default binder material in concrete specifications for water resources projects for over a century. The properties and performance of both fresh and hardened PC concrete are well documented, as is the superior durability and longevity of concrete structures that are properly designed and constructed. The environmental impact of manufacturing PC is also well documented, as regulators impose strict requirements on all cement producers to monitor and report emissions. According to the U.S. Environmental Protections Agency (EPA), the CO2 footprint of cement production in the U.S. accounts for 1.25% of the total U.S. CO2 emissions. While the cement industry has made considerable progress since the 1970’s to reduce its energy demand by 40%, the Portland Cement Association (PCA) and its members recognized that more must be done to tackle the carbon footprint of the cement and concrete industry. In 2021, PCA developed a Roadmap to Carbon Neutrality to lay out specific tasks and targets to achieve its goals.
Dam safety professionals have many opportunities to participate and engage with the cement and concrete industry to achieve carbon neutrality including optimization of concrete design and materials selection and facilitating a shift towards performance-based specifications. For example, replacing PC with portland-limestone cement (PLC or Type IL) in concrete for water resource projects delivers the same long-term durability and resilience with the added benefit of significantly reducing the carbon footprint. Portland-limestone cement offers up to a 10% lower carbon footprint than PC. Extensive comparison testing has demonstrated similar properties and performance of PLC when compared to PC in concrete.
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