2 Concrete
Concrete is a mixture of gravel, sand, cement and water.
Cement is the binder of this mixture and is main component that gives concrete its strength.
The process to make cement, globally, produces 8% of the world’s greenhouse gases. 1 ton of cement creates 1 ton CO
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Low Carbon Concrete Definition
Low carbon concrete is concrete produced with a lower carbon footprint than traditional concrete. This can be achieved through new construction methods, low carbon intensive cementitious material substitutes, utilizing local materials and facilities, and reducing cement content needs per material usage needs.
Typical elements that reduce cement use include fly ash (byproduct from coal-fired power plants) and steel slag (byproduct from steel mill blast furnaces).
Potential advancements in carbon reduction in concrete manufacturing are being studied in prefabricated concrete construction materials (pavers, bricks, cinder blocks), but is currently limited to prefabrication facilities. The application of CO 2 curing currently
cannot be applied to the field in ready-mix concrete.
4 2022 Fulton Widening – Guerneville Rd
to Piner Rd
2019 Fulton Rd Widening – Occidental
Rd to W 3rd St
• Structural design: 8” RCC on existing road base
• RCC Mix design: 530lbs cementitious material/ CY
• Cementitious material composition: 50% Portland
cement, 50% slag
• 28-day cylinder strength: 6,000+ psi
• Carbon dioxide output: 218 kg CO2/ M3
• Fresh Water Consumption 3.54 M3/M3
• Reduction in CO2 output: 46%
• Reduction in freshwater usage: 11%
• Structural design: 8” RCC on existing road base
• PCC Mix design: 658lbs cementitious material/ CY
• Cementitious material composition: 100% Portland
cement
• 28-day cylinder strength: 6,000+ psi
• Carbon dioxide output: 399 kg CO2/ M3
• Fresh Water Consumption 3.98 M3/M3
5 Benefits of concrete roads
• Carbonation of the pavement: all concrete undergoes carbonation, absorbing carbon from the atmosphere with the ability to capture 30- 70% of the CO2 produced in the manufacturing of Portland Cement. • High albedo: naturally lighter colored pavement that reduces the heat island effect and can assist in dropping localized air temperature up to 4 degrees.
• Less future maintenance: concrete roadways require less frequent maintenance, less costly maintenance, and less intrusive maintenance. • Less excavation/replacement depth: for some reconstruction projects, the depth of concrete is typically ½ that of asphalt to achieve the same structural section.
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Concerns with concrete roads
• Difficulty cutting into concrete for underground utility maintenance • Longer construction time for trench restorations
• Potential difficulty with leak detections
• Local streets do not have the same initial cost benefit – but show a longer- term maintenance benefit
8 Questions?