Early age hydration of model slag cement: Interaction among C3S, gypsum and slag with different Al2O3 contents

Wan, Zhi; Lima, Luiz Miranda de; Çopuroğlu, Oğuzhan

doi:10.1016/j.cemconres.2022.106954

Cited by 30 publications

(1 citation statement)

References 42 publications

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“…This implies a gradual reduction in the dissolution rate of slag and a decrease in the rate at which aluminates from slag and anhydrite form ettringite. Post 20.0-48.0 h of hydration, all pastes within the CA-CS-SSC system pastes exhibited a third hydration exothermic peak (second aluminate peak), likely originating from the reaction of aluminum in the slag with sulfate, culminating in an ettringite precipitate [42]. The third peak of the 1CA-4CS-SSC paste is more exothermic, owing to its elevated hydration level.…”

Section: Heat Hydrationmentioning

confidence: 99%

Effect of Calcium Aluminate and Carbide Slag on Mechanical Property and Hydration Mechanism of Supersulfated Cement

Qi,

Zhang,

Sun

2024

Buildings

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Supersulfated cement (SSC), a low-carbon, energy-efficient, eco-friendly cementitious material, is mainly made from industrial byproducts. However, SSC’s slow early strength development leads to inadequate initial hardening and reduced durability, which restricts its practical application. This study investigated the potential enhancement of SSC by incorporating calcium aluminate (CA) and carbide slag (CS) alongside anhydrite as activators to address its slow early strength development. The effects of varying CA and CS proportions on the mechanical property and hydration mechanism of CA-CS-SSC were examined. Results indicate that employing 1% CA and 4% CS as alkaline activators effectively activates slag hydration in the 1CA-4CS-SSC, achieving a compressive strength of 9.7 MPa at 1 day. Despite the limited improvement in early compressive strength of other mixtures with higher CA and lower CS proportions in the CA-CS-SSC system, all mixtures exhibited enhanced compressive strength during long-term hydration. After 90 days, ettringite formation in the CA-CS-SSC system decelerated, whereas anhydrite remained. Concurrently, the formation of C-S-H continued to increase, promoting late compressive strength. The mechanism for enhancing the early compressive strength of the CA-CS-SSC system is attributed to the swift hydration of CA with anhydrite, dissolution of fine slag particles, and reaction with anhydrite under conditions with suitable alkali content to augment the ettringite production. This process also generates a C-S-H and OH-hydrotalcite to fill the void in the skeleton structure formed by ettringite, resulting in a dense microstructure that improves early compressive strength.

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Section: Heat Hydrationmentioning

confidence: 99%

Effect of Calcium Aluminate and Carbide Slag on Mechanical Property and Hydration Mechanism of Supersulfated Cement

Qi,

Zhang,

Sun

2024

Buildings

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Insights into the Valorization of Electric Arc Furnace Slags as Supplementary Cementitious Materials

Andersson,

Isaksson,

Lennartsson

et al. 2023

J. Sustain. Metall.

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The transition to hydrogen-based reduction processes within the iron and steelmaking industry will generate new types of slag compositions that require valorization routes. Using slags as supplementary cementitious materials (SCMs) addresses the carbon dioxide emissions of the cement industry since the SCM requires neither calcination nor clinkering. Conventionally, ironmaking slags from the blast furnace (BF) are recycled as SCMs, i.e., ground granulated BF slag (GGBS). Ideally, future slags from electric arc furnaces (EAFs) operating on hydrogen-based direct reduced iron should be valorized analogously. Since the hydrogen-based process route is not yet realized in an industrial scale, the literature lacks data to support this valorization route, and additionally, literature on scrap-based EAF slags is scarce. Therefore, the present study aimed to offer insights into the utilization of ore-based EAF slags as SCMs based on an industrial slag sample from an EAF operating on hot briquetted iron. The slag was remelted, modified, and water-granulated in laboratory scale, and its performance as an SCM was compared to water-granulated ladle slag and two commercial GGBS. The results showed promising reactivities measured using the R3 isothermal calorimeter-based testing protocol. Based on the comparison to GGBS, the study indicated that generating reactive and appropriate SCMs from EAF slags will partly be a challenge in balancing the crystallization of the MeO-type solid solution rich in magnesia and addressing the iron oxide content in the amorphous phase. Graphical Abstract

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Rheology, mechanical properties, and hydration of synergistically activated coal gasification slag with three typical solid wastes

Xiang,

Qiu,

Zhao

et al. 2024

Cement and Concrete Composites

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Early age hydration of model slag cement: Interaction among C3S, gypsum and slag with different Al2O3 contents

Cited by 30 publications

References 42 publications

Effect of Calcium Aluminate and Carbide Slag on Mechanical Property and Hydration Mechanism of Supersulfated Cement

Effect of Calcium Aluminate and Carbide Slag on Mechanical Property and Hydration Mechanism of Supersulfated Cement

Insights into the Valorization of Electric Arc Furnace Slags as Supplementary Cementitious Materials

Rheology, mechanical properties, and hydration of synergistically activated coal gasification slag with three typical solid wastes

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