Influence of Alkalis on Natural Carbonation of Limestone Calcined Clay Cement Pastes

Li, Ruoying; Ye, Hailong

doi:10.3390/su132212833

Cited by 7 publications

(9 citation statements)

References 47 publications

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“…This results in a nonuniform distribution of mechanical properties, leading to a certain variability in compressive strength measurements. Moreover, the slightly larger error bars in the compressive strength of the bare cement cube suggest inherent material and procedural variabilities, as also reported in the literature. − This emphasizes the importance of precise sample preparation and consistent testing protocols.…”

Section: Resultssupporting

confidence: 57%

Consolidation of Iodine-Laden Adsorbents into Cementitious Waste Forms Suitable for Geological Disposal

Alghamdi,

Mondal,

Aina

et al. 2024

ACS Appl. Eng. Mater.

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Formulation of iodine-laden materials into waste forms suitable for permanent geological disposal is a daunting challenge. In this work, we present a feasible method for incorporating iodine-loaded UiO-66-NH 2 and Al 2 O 3 -DMAPS (3-N,Ndimethylaminopropyl-trimethoxysilane) adsorbents into low-calcium alkaline cement (type III) to produce consolidated waste forms. The UiO-66-NH 2 and Al 2 O 3 -DMAPS adsorbents exhibited 248 and 241 mg/g iodine capacity, respectively, upon exposure to iodine in aqueous phase at 25 °C for 48 h. After incorporation into cement matrix, the consolidated waste forms were characterized by X-ray photoelectron spectrometry (XPS), X-ray diffraction (XRD), and X-ray computed tomography (XCT). The results confirmed the presence of crystalline phases and uniform distribution of iodine-laden adsorbents within the cement matrix. Additionally, the effect of adsorbents loading on the mechanical integrity of the composites was investigated, and the results showed that the total porosity correlated strongly with the compressive strength. However, as the iodine-adsorbent/cement weight ratio increased, the compressive strength decreased, which also reduced the thermal stability of the composite. Lastly, the iodine leaching tests in deionized water confirmed the efficacy of the cementitious waste forms in permanently trapping iodine for safe geological disposal.

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Section: Resultssupporting

confidence: 57%

Consolidation of Iodine-Laden Adsorbents into Cementitious Waste Forms Suitable for Geological Disposal

Alghamdi,

Mondal,

Aina

et al. 2024

ACS Appl. Eng. Mater.

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“…As a result, this case also applies to LC 3 -50 cement-based concrete, which has a higher carbonation rate than OPC [11]. A Chinese study suggested that a low amount of calcium in LC 3 -50 cement comparatively OPC can be the reason for the lower binding capacity of carbon dioxide and having more carbonation depth in the LC 3 -50 system [32]. Figure 8(a) shows the LC 3 -50 and OPC samples kept in the carbonation chamber for exposure to 5% carbon dioxide up to 24 weeks.…”

Section: Carbonationmentioning

confidence: 85%

Comparative Study on LC3-50 with OPC Concrete Using Raw Materials from Pakistan

Sheikh

Jamil

Ayub

et al. 2023

Advances in Materials Science and Engineering

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The cement industry is expanding rapidly around the globe, despite its significant contribution to global carbon dioxide emissions. Likewise, in Pakistan, the cement industry produces million tons of cement and has a history of contributing as high as 10% of the country’s carbon dioxide emissions annually. The most effective technique for reducing carbon dioxide emissions is to use supplementary cementitious materials (SCMs). Limestone Calcined Clay Cement (LC3-50) is a recently developed cement blend comprised of 50% clinker, 30% calcined clay, 15% raw limestone, and 5% gypsum by weight. The focus of this research is to assess the mechanical properties and durability performance of LC3-50 cement composition formulated using raw materials from Pakistan. The comprehensive case study would help advance the research and commercialization activities in the country. In this study, compressive strength, split tensile, flexural, and pull-out tests were performed for evaluating the mechanical properties. For the assessment of durability, water permeability, sorptivity, carbonation, and rapid chloride penetration test (RCPT) tests were performed as per the available standards. It is concluded that the use of LC3-50 instead of ordinary Portland cement (OPC) improved the strength and durability of the end concrete.

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“…As shown in Table 1, the reference LC 3 paste (as control) was formulated by blending OPC, calcined kaolinite (metakaolin, MK), limestone (LS), and anhydrite calcium sulfate (Cs) powders at a mass ratio of 52.5:30:15:2.5 (following the work of reference [17]). To study the influence of MgO addition on the properties of LC 3 pastes, three incorporation dosages, including 2.5%, 5%, and 7.5% by powder mass (powder means the summation of anhydrous OPC+MK+LS+Cs) were considered, and the corresponding mixes were denoted as LC 3 _2.5M, LC 3 _5M, and LC 3 _7.5M, respectively.…”

Section: Methodsmentioning

confidence: 99%

“…Although LC 3 has been shown to possess excellent long-term mechanical and, on some occasions, superior durability performance (particularly the chloride and sulfate resistance) than conventional OPC [12][13][14], it tends to have relatively poor carbonation resistance [9,[15][16][17], thus increasing the corrosion risk of reinforcing steel embedded in carbonated concrete. The comparatively poor carbonation resistance of LC 3 primarily originates from a low amount of portlandite, which serves as a pH buffer in carbonating concrete.…”

Section: Introductionmentioning

confidence: 99%

Influence of Magnesium Oxide on Carbonation of Cement Paste Containing Limestone and Metakaolin

Jiang

Jin

2022

Sustainability

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One of the major durability concerns for limestone calcined clay cement (LC3) concrete is its high susceptibility to atmospheric carbonation that could lead to an early onset of electrochemical corrosion of reinforcing steel in concrete structures. Aimed at designing innovative LC3 formulations with potentially enhanced carbonation resistance, this preliminary study investigates the influence of reactive magnesia (MgO) on the early-age strength development, hydrates assemblage, and atmospheric carbonation resistance of ternary ordinary Portland cement-metakaolin-limestone blends with a constant 45% ordinary Portland cement (OPC) replacement level. The results show that the MgO addition impedes the formation of AFm phases (hemicarbonate and monocarbonate), likely through interfering reactions between metakaolin and portlandite. The formed brucite due to MgO hydration can uptake atmospheric CO2 to some extent, but at a considerably slower rate, in comparison with other hydrates in LC3 including AFm, AFt, and portlandite. The enhancement of carbonation resistance of LC3 pastes is insignificant by MgO addition of less than 5%.

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Influence of Alkalis on Natural Carbonation of Limestone Calcined Clay Cement Pastes

Cited by 7 publications

References 47 publications

Consolidation of Iodine-Laden Adsorbents into Cementitious Waste Forms Suitable for Geological Disposal

Consolidation of Iodine-Laden Adsorbents into Cementitious Waste Forms Suitable for Geological Disposal

Comparative Study on LC3-50 with OPC Concrete Using Raw Materials from Pakistan

Influence of Magnesium Oxide on Carbonation of Cement Paste Containing Limestone and Metakaolin

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