Characteristic microstructural phase evolution and the compressive strength development mechanisms of tricalcium silicate pastes under various initial carbonation curing environments

Cho, Seongmin; Suh, Heongwon; Im, Sumin; Kim, Gyeongryul; Kanematsu, Manabu; Morooka, Satoshi; Machida, Akihiko; Shobu, Takahisa; Bae, Sungchul

doi:10.1016/j.conbuildmat.2023.133866

Cited by 9 publications

(1 citation statement)

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“…Therefore, a decrease in the belite phase could lead to slower strength development in the later stages of cement hydration and reduced durability of the final concrete product. However, the exact impact of this decrease would depend on the cement's specific composition and performance requirements [21][22][23]. Overall, the alterations in the alite and belite phases in magnesium slag clinker production highlight the importance of carefully controlling the clinker composition to achieve the desired properties in the resulting Portland cement.…”

Section: Industrial Trial Studiesmentioning

confidence: 99%

Effect of Thermal Activation on the Mineralogical Structure of Magnesium Slag

Korkmaz

2024

IJCESEN

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Magnesium slag's production process is similar to the Portland cement production process. The raw material used is carbonate-containing dolomite, and is calcined in a rotary kiln at 850-900 oC. Afterwards, ferrosilicon and fluorite raw materials are added to the calcined material, they are ground together and turned into pellets, and then they are reduced at a temperature close to the firing temperature of Portland cement clinker (1250-1350 oC) to obtain crown magnesium and magnesium slag. The reduction time of pellet material in reduction furnaces is 12 hours. During this period, almost all of the magnesium minerals in the mixture material are reduced and taken as crown magnesium metal. The remaining material, described as magnesium production slag (reduction furnace waste), consists of Alite (C3S), Belite (C2S), Celite (C3A) and C4AF minerals contained in Portland cement clinker. Some of the minerals contained in Portland cement clinker in the rotary kiln are formed at temperatures below 1400 °C, which is the clinker firing temperature. The only difference other than the firing temperature is that after the Portland cement clinker is fired in the rotary kiln, the clinker is cooled rapidly, increasing the alite (C3S) crystals formed in its structure and preventing the alite minerals from turning back into belite (C2S) minerals. This study produced magnesium slags at different temperatures (1200-1350 oC) by thermal activation method in an industrial environment. The Bogue and XRD methods calculated the mineral phase amounts of the products produced.

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Section: Industrial Trial Studiesmentioning

confidence: 99%

Effect of Thermal Activation on the Mineralogical Structure of Magnesium Slag

Korkmaz

2024

IJCESEN

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Comparison of thermogravimetry response of alkali-activated slag and Portland cement pastes after stopping their hydration using solvent exchange method

Bílek,

Švec,

Másilko

et al. 2024

J Therm Anal Calorim

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The critical step for any subsequent instrumental analysis of cementitious binders is to stop their hydration reactions, i.e., to remove free water. One of the most available techniques is a solvent exchange method. However, the solvents are known to be strongly bound in ordinary Portland cement (OPC) paste and alter the results of thermogravimetric analysis (TGA) and sensitive hydrates, while their effect on TGA response of alkali-activated slag (AAS) has not been comprehensively investigated. Therefore, the objective of this paper is to track the effects of fundamental aspects of the solvent exchange on the TGA response of AAS with different sodium activators (hydroxide, carbonate, waterglass) and to support these results by X-ray diffraction and effluent gas analysis. All solvents used (acetone, diethyl ether, isopropyl alcohol, ethanol, and methanol) affected the TGA response of all tested pastes, and their effect was enhanced by prolonged immersion time. All solvents induced an additional mass loss at around 800 °C and, especially for OPC paste, increased in situ carbonation, even in an inert atmosphere. Methanol and ethanol had a detrimental effect on ettringite and decreased the basal distance of the C–(A)–S–H gel, while they only marginally affected gaylussite. For AAS, hydration stoppage by washing out the alkali-rich pore solution with water was also investigated and can usually be recommended (except for its detrimental effect on gaylussite), as it is more efficient than organic solvents, which lack solubility for activators. Methanol and ethanol are the most suitable alternatives, particularly for NaOH.

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