Recycling CO2 from flue gas for CaCO3 nanoparticles production as cement filler: A Life Cycle Assessment

The physicochemical properties of Portland cement blended with calcium carbonate with different morphologies as a supplementary cementitious material

“…Portland cement blend with a 15% clinker substitution is therefore responsible for 0.327 kgCO 2 eq/kg, a 64% reduction, when the sodium hydroxide for the capture process is produced using the membrane cell hydrolysis method (Scenario 2, Table 12). This reduction is comparable to that of Batuecas et al (2021) who found a reduction to 0.3 kgCO 2 /tonne of Portland cement using a ionic liquid based carbon capture method. While it is possible to add more calcium carbonate according to the European Standard (EN 197-1:2011(EN 197-1: , 2011, 15% was used in this calculation as it provides near equivalent strength to that of the OPC considered in this study.…”

“…This value includes the substitution of upto 5% of the cement clinker with minor additives such as gypsum and limestone which have a lower kg CO 2 eq/kg than cement clinker. The value for climate change impact is comparable to those determined by Lehne and Preston (2018) and Batuecas et al (2021) who estimate that the CO 2 potential of Portland cement is 0.93 and 0.96 kgCO 2 /kg cement, respectively.…”

“…The mineralisation process can be used to control the grain size and morphology of the calcium carbonate. The CO 2 sequestered in the mineralised calcium carbonate can potentially reduce the emissions from 0.96 kgCO 2eq /kg to as little as 0.3 kgCO 2eq /kg, depending on the carbon capture method utilised (Batuecas et al, 2021). Through controlling the ageing time of the calcium carbonate and pH of the calcium source in the precipitation process, amorphous calcium carbonate can be produced which has not been added to Portland cement as an additive.…”

Opportunities and challenges for engineering construction materials as carbon sinks

“…The use of alternative clinkers that have lower enthalpies of reaction and decarbonation-related emissions has been proposed to reduce GHG emissions from the production of cement [41][42][43]; certain alternative clinkers can cure through carbonation as opposed to hydration, which could contribute to an uptake of CO2 in the production of concrete [42,44]. Engineered carbonate minerals, such as nano-CaCO3 produced from certain CCUS technologies and carbonate bearing slags, have been shown to improve some concrete properties when used as a filler and could mitigate several environmental impacts [45,46]. It has been suggested that a combination of CO2 mineralization, direct air capture, and clinker content reduction can sequester 44-85% of the cement production emissions [47].…”

“…Reports have projected CCUS implementation in cement production plants to begin in 2030, and as such, a rigorous understanding of the technology and environmental impacts is required [129]. Several studies analyzing post-combustion CCUS reported it leading to lower GHG emissions than traditional cement production, but driving harmful increases for human health impacts [45,80,81,130], thus potentially shifting the problem from CO2 emissions to another impact category. Further, the use of CO2 captured from power plants in CCUS within concrete has been explored, but recent findings suggest a loss of mechanical strength could result in some of these technologies leading to higher CO2 emitting systems than conventional concrete [131].…”