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Admixtures and Sequestered Carbon

As attention gets paid to the climate crisis looming over our future, construction is among the industries often pointed to as having severe problems. Within the construction field, concrete is a major target for limiting or eliminating CO2 emissions. From research facilities to field operations, work is being done, partnerships are being developed, and new methods and products are resulting.

For example, CarbonBuilt and Master Builders Solutions are collaborating on the development of admixtures for use with CarbonBuilt’s low-cost, low carbon technology platform. Master Builders Solutions comprehensive portfolio encompasses concrete admixtures, cement additives, chemical solutions for underground construction, waterproofing systems, concrete repair, and protection systems.

These admixtures will facilitate the application of CarbonBuilt’s Reversa technology to a wide range of precast concrete products, including pavers, segmented retaining walls, hollow core slabs, pipes, manholes, and other types of dry- and wet-cast products. In addition, the parties will explore the use of existing and new admixture chemistries to increase carbon dioxide utilization without sacrifice to product performance, product cost or process cycle time.

CarbonBuilt’s core technology emerged out of the Institute for Carbon Management at the University of California, Los Angeles. The UCLA team demonstrated that dilute CO₂ streams such as those from industrial emissions could be cost-effectively converted into concrete using widely available low-cost and low-carbon materials. In early 2021, the UCLA CarbonBuilt team was awarded the prestigious NRG COSIA Carbon XPRIZE, the grand prize in five-year-long global contest designed to foster and fund the development of breakthrough technologies that convert CO₂ emissions into usable products.

CarbonBuilt’s Reversa process includes innovations to both the concrete mix design and its curing process. On the formulation side, portlandite (also known as calcium hydroxide or hydrated lime) is used, reducing the usage of traditional Portland cement and increasing the use of low-cost and low-carbon supplementary cementitious and filler materials. Concrete products are then formed using the same processes and equipment that are used today.

After forming, the concrete products are cured with CO₂ using a process that does not require expensive capture, compression, or purification of the CO₂, high temperature or elevated pressure.  This flexibility enables use of a wide range of CO2 containing streams ranging from point-source or distributed emissions that can be used directly, to merchant gas from such sources, to emerging direct air capture technologies.

The Reversa process reduces emissions by at least 60%, and potentially more than 100%, through a combination of utilization (permanently embedding CO₂ into the concrete) and avoidance (reducing CO₂ emissions associated with the raw materials). 

While the initial application will be in concrete masonry, its use will be expanded to include the broader precast concrete marketplace.

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