Carbon dioxide uptake by pure Portland and blended cement pastes

Thermodynamic Modeling and Experimental Study of Carbonation of Alkali-Activated Slag Cements

“…The Na 2 SO 4 - and Na 2 CO 3 -activated samples exhibit a total CO 2 uptake of approximately 10 g/100 g unreacted slag, while the Na 2 SiO 3 - and NaOH-activated slags show CO 2 uptakes of 15 g/100 g and 19 g/100 g, respectively, which is related to both the different degrees of slag reaction and different chemistries depending on the activator used. These values are comparable or higher than that of hydrated neat and blended Portland cement carbonated in natural conditions for a few years . It is possible that the high alkalinity of the NaOH activator as compared to the other activators may lead to a higher reaction degree of slag.…”

“…These values are comparable or higher than that of hydrated neat and blended Portland cement carbonated in natural conditions for a few years. 44 It is possible that the high alkalinity of the NaOH activator as compared to the other activators may lead to a higher reaction degree of slag. It is known that hydrotalcite-like LDH is less stable in the presence of sodium silicate 23 ; thus, use of Na 2 SiO 3 as an activator may lead to increasing the carbonation extent.…”

Comparative effects of different real conditions in the microstructure and properties of ternary blended cement mortars for being used in rehabilitation works

“…On the other hand, the search of solutions for reducing the energy and environmental problems caused by the manufacture of Portland cement (Benhelal et al, 2021) is a main issue to be addressed in the construction materials field, within the current context with the aim of lessening the global warming, according to the objectives of sustainable development. In this line, the development of eco-friendly cements (Restrepo-Baena et al, 2020;Andrade and Sanjuán, 2021) with additions, could be a good alternative for contributing to reach a more sustainable industry of cement. Among the different environmental advantages for the utilization of blended cements with additions, it is noteworthy to underline the lessening of CO 2 emissions and energy consumption, because of the lower quantity of clinker required for manufacturing commercial cements.…”

Enhanced carbonation curing of cement pastes with dolomite additive

“…After the hydration process, the phases in concrete include calcium hydroxide (CH), calcium silicate hydrates (C‐S‐H), calcium aluminate hydrate, ettringite, unreacted clinker minerals (C 3 S, C 2 S), and so on 9,10 . In the carbonation process, these components can react with CO 2 to form carbonates, which leads to a CO 2 uptake of up to 30% of the mass of calcined cement 11 . Moreover, carbonation causes numerous changes in cement pastes, including notable changes in pore size distribution, porosity, and strength 12,13 .…”

“…9,10 In the carbonation process, these components can react with CO 2 to form carbonates, which leads to a CO 2 uptake of up to 30% of the mass of calcined cement. 11 Moreover, carbonation causes numerous changes in cement pastes, including notable changes in pore size distribution, porosity, and strength. 12,13 Precipitation of CaCO 3 preferentially occurs in pores, resulting in the pore size distribution curves to shift towards smaller pore diameters and reducing the total volume of pores per gram of paste.…”