Carbonation of Recycled Concrete Aggregates
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Rising costs of natural mined aggregate and heavy transport nationwide are driving demand for aggregate sources that can lower costs and increase sustainability. Over 300 million tons of waste aggregate is generated as construction and demolition waste in the US every year, and some of this is recycled - but crushed concrete cannot generally be used as aggregate to mix new concrete because of its water absorption and mineral properties.
With the support of the Volpe National Tranportation Systems Center of the US Department of Transportation, Nalari Scientific has developed and built a prototype Recycled Concrete Aggregate Carbonator, that accepts crushed old concrete (RCA), and strengthens it into usable aggregate for construction projects, including US DOT 703.01, AASHTO M6 Class B, and other categories of aggregates. It also permanently stores absorbed CO2 as solid mineral phases. The Carbonator is based on patent-pending technologies for processing solid aggregates in an atmospheric reactor (US Pat. App. #18/639,924).
These videos show the movement of recycled concrete aggregates within Nalari Scientific's RCA Carbonator, while being exposed to a carbon dioxide atmosphere
RCA_Auger_1.mp4Movement of Recycled Concrete Aggregates (RCA) through Auger Conveyor
RCA_Auger_2.mp4Movement of RCA through Auger Conveyor
RCA_Auger_Transfer.mp4RCA Transfer Between Auger Conveyors
Carbonating RCA Strengthens It and Makes It Usable In Mortars and Concrete
Our triplicate uniaxial compressive strength tests on Type S mortars (ASTM C39) made using RAW versus CARBonated RCA (left) show a 62% strength increase over 28 days.
Nalari Scientific's RCA Carbonator can lower construction aggregate and transport costs, lower Construction and Demolition Waste landfill tipping fees, lower embodied carbon and emissions profiles for concrete construction projects, and provide profitable utilization of waste CO2.
Our research is ongoing - part of the project carried out with support from the U.S. Department of Transportation, SBIR Phase I Award #6913G21P800039, Rapid and Continuous RCA Carbonation With Vapor Loss Minimization, awarded to PI Dr. Daniel Deocampo. If you are interested in finding out more about our technology or partnering opportunities please contact deocampo@nalariscientific.com.
March 15, 2025
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