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Methods to sequester and store atmospheric CO2 are critical to combat climate change. Alkaline-rich bioashes are potential carbon fixing materials. This work investigates potential co-benefits from mineralizing carbon in biomass ashes and partially replacing high embodied greenhouse gas (GHG) Portland cement (PC) in cement-based materials with these ashes. Specifically, rice hull ash (RHA), wheat straw ash (WSA), and sugarcane bagasse ash (SBA) were treated to mineralize carbon, and their experimental carbon content was compared to modeled potential carbonation. To understand changes in the cement-based storage materials, mortars made with CO2-treated WSA and RHA were experimentally compared to PC-only mortars and mortars made with ashes without prior CO2 treatment. Life cycle assessment methodology was applied to understand potential reductions in GHG emissions. The modeled carbonation was ∼18 g-CO2/kg-RHA and ∼180 g-CO2/kg-WSA. Ashes oxidized at 500 °C had the largest measured carbon content (5.4 g-carbon/kg-RHA and 35.3 g-carbon/kg-WSA). This carbon appeared to be predominantly residual from the biomass. Isothermal calorimetry showed RHA-PC pastes had similar heat of hydration to PC-pastes, while WSA-PC pastes exhibited an early (at ∼1.5 min) endothermic dip. Mortars with 5 % and 15 % RHA replacement had 1–12 % higher compressive strength at 28 days than PC-only mortars, and milled WSA mortars with 5 % replacement had 3 % higher strength. A loss in strength was noted for the milled 15 % WSA, the CO2-treated 5 %, and the 15 % WSA mortars. Modeled reductions in GHG emissions from CO2-treated ashes were, however, marginal (<1 %) relative to the untreated ashes. 

Abstract The construction and building materials (CBM) production industries, such as cement, steel, and plastics that are responsible for a substantial share of global CO₂emissions, face increasing pressure to decarbonize. Recent legislative initiatives like the United States (US) federal Buy Clean Initiative and the World Green Building Council’s decarbonization plan for Europe highlights the urgency to reduce emissions during CBM production stages. However, there remains a gap in addressing the localized environmental and social impacts of these industries as well as a necessary understanding of how decarbonization efforts may change local impacts. This study introduces a framework for quantifying the disproportionate impacts (I_d) of 12 CBM production facility categories on communities of color and low-income demographics across the US. Using geographical and environmental data from the 2017 National Emissions Inventory (NEI), we assess these impacts at four spatial scales: census tract, county, state, and national. Results show that across all scales, many CBM production facilities impose disproportionate impacts. The geographical disproportionate impact (I_G,d) shows the greatest burdens at the broadest spatial scales, whereas the environmental disproportionate impact (I_E,d) indicates highest burdens at more localized levels. Based on this spatial understanding, we provide methods that can be implemented to support community engagement and mitigate damages to populations neighboring industrial materials manufacturing. These findings offer valuable insights into the relationship between facility locations, emissions, and demographic groups, providing a basis for more targeted environmental justice policies aimed at mitigating these disproportionate impacts. 

Population growth and urbanization over the coming decades are anticipated to drive unprecedented demand for infrastructure materials and energy resources. Unfortunately, factors such as the degree of resource consumption, the energy-intensive nature of production, and the chemical-reaction driven emissions make infrastructure materials production industries among the greatest contributors to anthropogenic CO2 emissions. Yet there is an often-overlooked potential environmental benefit to infrastructure materials: most remain in use for decades and their long service lives can facilitate extended storage of carbon. In this perspective, we present an overview of recent technological advancements that can support infrastructure materials acting as a global, distributed carbon sink and discuss areas for further research and development. We present mechanisms to quantify the extent to which the embodied carbon will be removed from the carbon cycle for a long enough period of time to provide carbon sequestration and climate benefit. We conclude that it is possible to unlock the vast potential to engineer a carbon sequestration system that simultaneously meets societal need for expanding infrastructure systems; however, complexities in how these systems are engineered must be systematically and quantitatively incorporated into materials design.