The role of timely controlled PCC in concrete performance development

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The proposed research will study fundamental science on timely controlled precipitated calcium carbonate (PCC) technology for carbonation induced hydration and its associated CO2 sequestration in concrete for combined environmental, technical and economical benefits. A significant fraction of the CO2 discharged to the atmosphere comes from point sources. Finding commercial uses of as-captured or recovered CO2 at point sources is critical to greenhouse gas emissions reduction. One of the promising approaches is to sequester carbon dioxide in concrete through their productions. Research at McGill University has shown that approximately 1.8 million tones of CO2 can be sequestered annually in concrete products such as blocks, pavers, cement boards and fibreboards, if all four products in US and Canada are carbonation treated. It reduces CO2 emission from cement industry by 2.6%. It is significant but still modest. To further enhance the sequestration capacity by concrete, higher reaction efficiency and more products of niche applications should be explored. The proposed research will focus on carbonation of general use concrete at early ages to establish a process in which carbonation and hydration can occur sequentially to sequester sufficient carbon while maintaining hydration features. The objectives are (1) to understand the mechanism of PCC formation at early age (0.5 to 24 hours), (2) to quantify CO2 uptake by carbonation at different ages, (3) to investigate the advantages of having PCC in concrete, (4) to develop pressurized and vacuum PCC technology using recovered CO2 and flue gas, (5) to fabricate concrete pipes by carbonation for carbon uptake and sulfate resistance, (6) to perform controlled carbonation to precast concrete for carbon uptake and alkali silica reaction (ASR) reduction, (7) to perform strong carbonation to precast concrete reinforced by GFRP rebar for carbon uptake and durability, (8) to develop a vacuum carbonation for cast-in-place concrete for carbon uptake and fast setting. The proposed carbon sequestration technology is sustainable because it is an integrated part of economy and can be used anywhere worldwide for decades to come.