ACI Online Learning & Presentations

Two approached to reducing the carbon footprint of concrete are to, 1. Reduce the clinker content of the cementitious binder and, 2. Reduce the total binder content. For the first, combinations of supplementary cementitious materials can be combined with Type IL cements while still attaining early-age strength development with at least a 40% reduction in clinker content. For the second, optimizing aggregate gradations with at least three components can result in savings of up to 15% of the required cementitious materials content while also reducing concrete permeability and shrinkage. The methodologies for combining both of these approaches will be discussed.

This study investigated a new approach to dispersion of carbon nanofibers (CNFs) in cement paste by coating rice husk ash (RHA) particles using a natural polymer binder. Light Chitosan with low molecular weight was used to provide bonding between CNFs and SiO2 from the RHA substrate. Mechanical properties namely, compressive strength and flexural properties of paste specimens were assessed to evaluate the efficiency of the applied method. Microstructural analysis was carried out using FTIR, XRD, TGA, and SEM to investigate the effects of the coating process on the hydration products and to explain the mechanical properties of specimens with the modified RHA. The results showed that 15% and 5% modified RHA increased the compressive strength and flexural strength of paste specimens at 28 days by 53% and 187%, respectively. Microstructural analysis showed that the coating process delayed the hydration, however, the physical crosslinking effect of carbon nanofibers enhanced the mechanical properties at all ages.

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The benefits of binders produced with significantly reduced, little, or no process energy that have a small carbon footprint, are composed of recycled and/or renewable resources, and have minimal environmental impact will be discussed.

The benefits of binders produced with significantly reduced, little, or no process energy that have a small carbon footprint, are composed of recycled and/or renewable resources, and have minimal environmental impact will be discussed.

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This session provides a general overview of the cement and concrete industry initiatives in climate change mitigation and adaptation, along with a review of the National Concrete Pavement Technology Center concrete pavement roadmap work on sustainability. Presentations include topics such as blended cements, recycled aggregate, internal curing, and green streets. This session showcases the many sustainable benefits of using concrete pavement and climate change initiatives of the cement and concrete industry to reduce our carbon and energy footprints.

The cement and concrete industries are coming under more and more pressure to reduce the Global Warming Potential (GWP) for their products. The greatest contributor of CO2 and greenhouse gases in concrete is the portland cement. This presentation is a general review of the strategies being used today, and possibly in the future, by managers of cement plants to lower greenhouse gas emissions at manufacturing sites. These strategies include: improving plant efficiency and fuel utilization, using lower CO2 fuels, using more waste fuels, manufacturing more blended cements, and carbon capture, utilization, and storage.

Some CO2 emissions during cement production process are inevitable and cannot be eliminated using established techniques of clinker substitution and alternative fuels. Therefore, new approaches are needed to deal with this CO2 in order to reach our vision of carbon-neutral concrete. Carbon capture technologies provide a solution to ultimately reduce hard-to abate emissions.

A unique and innovative approach to reach carbon neutrality using the entire value chain of cement and concrete and incorporating that value chain within the circular economy.