Advances in understanding ye'elimite-rich cements

Haha, Mohsen Ben; Winnefeld, Frank; Pisch, A.

doi:10.1016/j.cemconres.2019.105778

Cited by 110 publications

(43 citation statements)

References 179 publications

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“…For example, calcium sulfo-aluminate (CSA) cements are well-known products, largely used in China. This technology is a real alternative compared to Portland cement as it is based on aluminum chemistry avoiding the decarbonation of limestone 104 . The main issue is lack of high-alumina raw materials, which limits its implementation to a few percent of cement production at most.…”

Section: Breakthrough Solutions the Reality Behind The Hypementioning

confidence: 99%

Environmental impacts and decarbonization strategies in the cement and concrete industries

Habert

Miller

John

et al. 2020

Nat Rev Earth Environ

634

269

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The use of concrete is under scrutiny as it appears as one of the few human activities where the transition toward a post-carbon society is not possible unless large investments in risky carbon capture and storage are made. With current urbanization, it is also a sector that is expected to continuously grow, leading to increased resource consumption and emissions. In this review, we aim to shed light on the available solutions that can be implemented in the short and long term to reduce greenhouse gas emissions. Rather than waiting for disruptive technologies that could transform a very slow moving and risk-averse construction sector, this review focuses on the small improvements that every stakeholder involved along the value chain of concrete production and use can achieve. We stress how significant the combined effect of these marginal gains can be. By balancing societal needs, environmental requirements, and technical feasibility, the intention of this review is to show credible pathways for a transition to sustainable use of concrete. Key points• Cement usage is so massive, more than 4 billion tonnes per year worldwide, that large-scale replacement by other materials within the next decade is not possible.• Environmental impact of cement and concrete is low per unit of material, but the amount used makes the impact of the sector highly significant.• Reductions in CO 2 emissions are possible through successive improvement all along the cement and concrete value chain: less clinker in cement, less cement in concrete, less concrete in structures, and less replacement of structures.• By engaging all stakeholders of the construction sector, immediate savings of the order of 50% can be reached without heavy investment in new industrial infrastructure or modification of standards.• Research and development need urgently to be conducted for post-2050 construction to meet future emissions reduction targets. Alternative cement and faster carbonation of concrete should be explored.

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Section: Breakthrough Solutions the Reality Behind The Hypementioning

confidence: 99%

Environmental impacts and decarbonization strategies in the cement and concrete industries

Habert

Miller

John

et al. 2020

Nat Rev Earth Environ

634

269

View full text Add to dashboard Cite

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“…It is, therefore, the presence and availability of dissolved Al species, rather than sulfate, which limits the ettringite formation in Ca-rich CFBC ash. This is further supported by the absence of excess Al-hydroxide precipitation, characteristic in CSA cements, even though the Al-hydroxide precipitation is also suppressed by the presence of Ca(OH)2 [51,53] that is abundant in hydrated Ca-rich CFBC fly ashes. In Ca-rich oil shale CFBC ashes the main readily available Al sources are the amorphous Ca-Si-Al-(K) cenospheres and/or residual dehydroxylated aluminosilicate clays.…”

Section: Discussionmentioning

confidence: 71%

“…In addition, the dissolution of Ca-and Ca-Mg silicates C2S (belite) and merwinite/akermanite, continuing over the full length of the hydration period, possibly produces a heterogeneous C-(A)-S-H gel-like phase, with additional crystalline portlandite Ca(OH)2 forming also by the hydration of lime. In this sense the activated Ca-rich CFBC fly ash behaves similarly to calcium sulfoaluminate (CSA) cement, which is considered as one of the low-CO2 alternatives of ordinary Portland cement [51]. In CSA hydration, strength development is provided by the hydration of the ye'elimite (Ca4(AlO2)6SO3) in the presence of gypsum (CaSO4 2H2O), producing ettringite and nanocrystalline Al(OH)3, and depending on cement composition other phases as monosulfate, C-S-H phase, strätlingite, or hydrogarnet [52][53][54].…”

Section: Discussionmentioning

confidence: 99%

Mechanical Activation of the Ca-Rich Circulating Fluidized Bed Combustion Fly Ash: Development of an Alternative Binder System

et al. 2020

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Mechanical activation of the calcium-rich fly ash formed in circulating fluidized bed combustion (CFBC) boilers was investigated to enhance the compressive strength performance of the pastes. We studied the effect of the activation on the physical, chemical, and mineral characteristics of fly ash and its pastes. Our study shows that already a short mechanical activation yields a 10-fold improvement in the compressive strength of the pastes, reaching 60 MPa after 90 days of curing without any chemical activation or blending. Mechanical activation caused fragmentation of large porous aggregates in the raw ash enhancing the physical properties and reactivity of fly ash particles. Similarly to calcium sulfoaluminate cements, the mechanical strength was provided by the formation of abundant ettringite and possibly C-(A)-S-H gel-like phase that created a highly compact microstructure. Our findings suggest that mechanically activated Ca-rich CFBC fly ash can be successfully used as an alternative binder.

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“…Ettringite and aluminum hydroxide are formed from calcium sulphoaluminate in the presence of water and a source of sulphate. The more calcium sulphoaluminate is added, the more ettringite forms, the higher the volume of hydrates, and the lower the amount of available water and available space for growing hydrates [26,51,53]. It is ettringite which gives the initial strength (reaction detected by isothermal calorimetry).…”

Section: Compressive Strengthmentioning

confidence: 99%

The Incorporation of Steel Slag into Belite-Sulfoaluminate Cement Clinkers

et al. 2021

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The potential use of steel slag from treated steel slag in belite-sulfoaluminate cements was investigated in this study. Cement clinkers with two phase compositions were synthesized, allowing the incorporation of different amounts of steel slag. The phase composition and microstructure of cement clinkers at three different sintering temperatures were studied by X-ray powder diffraction and the Rietveld method, as well as scanning electron microscopy with energy dispersive spectrometry. The results showed that the targeted phase composition of clinkers was achieved at a sintering temperature of 1250 °C. However, a higher amount of perovskite instead of ferrite was detected in the clinker with a higher content of Ti-bearing bauxite. Apart from the main phases, such as belite, calcium sulfoaluminate, and ferrite, several minor phases were identified, including mayenite, perovskite, periclase, and alkali sulfates. In both clinker mixtures, a higher content of MgO in the steel slags resulted in the formation of periclase. Furthermore, the hydration kinetics and compressive strength at 7 and 28 days were studied in two cements prepared from clinkers sintered at 1250 °C. As evidenced by the results of isothermal calorimetry, the hydration kinetics were also influenced by the minor clinker phases. Cement with a higher content of calcium sulfoaluminate phase developed a higher compressive strength.

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Advances in understanding ye'elimite-rich cements

Cited by 110 publications

References 179 publications

Environmental impacts and decarbonization strategies in the cement and concrete industries

Environmental impacts and decarbonization strategies in the cement and concrete industries

Mechanical Activation of the Ca-Rich Circulating Fluidized Bed Combustion Fly Ash: Development of an Alternative Binder System

The Incorporation of Steel Slag into Belite-Sulfoaluminate Cement Clinkers

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