Mitigating CO₂ emissions of concrete manufacturing through CO₂-enabled binder reduction

Abstract

Past studies on CO 2 utilization in the concrete industry have primarily focused on maximizing sequestered CO 2 , while focusing less on CO 2 avoidance possible by reducing binder use through the addition of CO 2 to concrete formulations. In this paper, we study the net CO 2 reduction and cost benefits achievable by reducing binder loading while adding CO 2 via three approaches: carbonation during curing, carbonation during mixing, or carbonation with recycled concrete aggregate. These techniques are evaluated for a cohort of concrete formulations representing the diverse mixture designs found in the US ready-mixed and precast industries. Each formulation is optimized for reduced binder loading where the use of CO 2 directly in the formulation recovers the lost compressive strength from reduced binder. We show that over an order of magnitude more CO 2 can be avoided when binder reduction is jointly implemented with CO 2 utilization compared to utilizing CO 2 alone. As a result, nearly 40% of the annual CO 2 emissions from the US concrete industry could, in principle, be eliminated without relying on novel supplemental materials, alternative binder, or carbon capture and sequestration. The recently amended 45Q tax credit will not incentivize this strategy, as it only considers carbon sequestration. However, we find that the saved material cost from reduced binder use on its own may provide a significant economic incentive to promote the joint strategy in practice. We conclude that the real value of CO 2 utilization in concrete hinges on exploiting CO 2 -induced property changes to yield additional emission reduction, not by maximizing absorbed CO 2 .

Emerging concepts in intermediate carbon dioxide emplacement to support carbon dioxide removal

“…However, it is projected that the near-term implementation of CO 2 for cement production in the United States (US) would require transporting less than a kilo-tonne of CO 2 per year to over 8000 distributed production sites. 11 Carbon dioxide can also be stored semi-irreversibly for very long periods of time through the mineralization of natural or waste alkaline materials. These reactions achieve the ultimate goal of carbon sequestration and thus are excellent storage solutions, but reputable reviews suggest they will be limited by rates of reaction and starting materials in the near future.…”

An Economic Analysis of the Use of Local Natural Waste: Volcanic Ash of Mt. Etna Volcano (Italy) for Geopolymer Production

“…In this scenario, Miller et al [61] show that in 2012 concrete production was responsible for 9% of global industrial water withdrawals (approximately 1.7% of total global water withdrawal). Furthermore, the global demand for OPC is set to increase further by 2050, especially in developing countries [62], where water stress is expected to be a more serious problem [45].…”

Investigation of Carbonation Kinetics in Carbonated Cementitious Materials by Reactive Molecular Dynamics Simulations

“…Cement concrete is a calcium-containing material, so it can capture and store carbon dioxide itself mainly via three ways: (1) carbonating the raw materials of cement concrete before concrete preparation, such as waste cementitious materials and recycled aggregate; − (2) carbonating the fresh concrete during the mixing period of raw materials; − and (3) accelerated carbonation curing of cement concrete. − Direct carbonation of the recycled aggregate can improve its density, reduce water absorption, and improve mechanical properties. − Carbonation curing as well as fresh concrete carbonation during its mixing can also improve the performance of cement concrete . Among these three methods, carbonation curing has the highest carbon sequestration efficiency, which is about 3–4 times that of the other two methods . As a result, carbonation curing has become the most commonly used way and has attracted more and more attention.…”