In-situ laboratory X-ray diffraction applied to assess cement hydration

Matos, Paulo Ricardo de; Neto, José S. Andrade; Jansen, Daniel; Torre, Ángeles G. De la; Kirchheim, Ana Paula; Campos, Carlos Eduardo Maduro de

doi:10.1016/j.cemconres.2022.106988

Cited by 33 publications

(5 citation statements)

References 160 publications

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“…These phases came from the aggregates used (CG, FG, S1 and S2). The portlandite (Ca(OH) 2 ) (44-1481) [ 60 ], ettringite (Ca 6 Al 2 (SO 4 ) 3 (OH) 12 ·26 H 2 O) (00-0059) [ 60 ] and calcium silicate hydrate (2CaSiO 3 ·3H 2 O) (03-0556), also named C-S-H [ 60 ] phases, were the main hydration reactions [ 95 , 96 , 97 ]. The same phases were found at 14 and 28 days with no significant changes.…”

Section: Resultsmentioning

confidence: 99%

Carbon Emission Evaluation of CO2 Curing in Vibro-Compacted Precast Concrete Made with Recycled Aggregates

et al. 2023

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The objective of the present study was to explore three types of vibro-compacted precast concrete mixtures replacing fine and coarse gravel with a recycled/mixed concrete aggregate (RCA or MCA). The portlandite phase found in RCA and MCA by XRD is a “potential” CO2 sink. CO2 curing improved the compressive strength in all the mixtures studied. One tonne of the mixtures studied could be decarbonised after only 7 days of curing 13,604, 36,077 and 24,635 m3 of air using natural aggregates, RCA or MCA, respectively. The compressive strength obtained, XRD, TGA/DTA and carbon emission evaluation showed that curing longer than 7 days in CO2 was pointless. The total CO2 emissions by a mixture using CO2 curing at 7 days were 221.26, 204.38 and 210.05 kg CO2 eq/m3 air using natural aggregates, RCA or MCA, respectively. The findings of this study provide a valuable contribution to carbon emission evaluation of CO2 curing in vibro-compacted precast concrete with recycled/mixed concrete aggregates (RCA or MCA). The technology proposed in this research facilitates carbon capture and use and guarantees enhanced compressive strength of the concrete samples.

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Section: Resultsmentioning

confidence: 99%

Carbon Emission Evaluation of CO2 Curing in Vibro-Compacted Precast Concrete Made with Recycled Aggregates

et al. 2023

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“…The main reason is that magnesium slag has limited activity in this condition without alkali activation. When the amount of magnesium slag in the system is less than 20%, Ca(OH) 2 produced during the hydration process of cement can play a significant role in activating the magnesium slag, so that the magnesium slag can better participate in the hydration process [56]. As a result, magnesium slag can be used to replace part of the cement within a 20% dosage whilst the compressive strength can also be improved.…”

Section: Magnesium Slag and Granulated Blast Furnace Slag As Replacem...mentioning

confidence: 99%

Structural Characteristics and Cementitious Behavior of Magnesium Slag in Comparison with Granulated Blast Furnace Slag

Lu,

Zhao,

Zhang

et al. 2024

Materials

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Magnesium slag is a type of industrial solid waste produced during the production of magnesium metal. In order to gain a deeper understanding of the structure of magnesium slag, the composition and microstructure of magnesium slag were investigated by using characterization methods such as X-ray fluorescence, particle size analysis, X-ray diffraction, Fourier transform infrared spectroscopy and scanning electron microscopy. In addition, the state of Si occurrence in magnesium slag was analyzed using a solid-state nuclear magnetic resonance technique in comparison with granulated blast furnace slag. An inductively coupled plasma-optical emission spectrometer and scanning electron microscope with energy dispersive X-ray spectroscopy were used to characterize their cementitious behavior. The results show that the chemical composition of magnesium slag mainly includes 54.71% CaO, 28.66% SiO2 and 11.82% MgO, and the content of Al2O3 is much lower than that of granulated blast furnace slag. Compared to granulated blast furnace slag, magnesium slag has a larger relative bridging oxygen number and higher [SiO4] polymerization degree. The cementitious activity of magnesium slag is lower compared to that of granulated blast furnace slag, but it can replace part of the cement to obtain higher compressive strength. Maximum compressive strength can be obtained when the amount of magnesium slag replacing cement is 20%, where the 28-day compressive strength can be up to 45.48 MPa. This work provides a relatively comprehensive analysis of the structural characteristics and cementitious behavior of magnesium slag, which is conducive to the promotion of magnesium slag utilization.

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“…The progress of hydration was followed using in situ, time-resolved measurements by X-ray diffraction on specimens of cement paste placed on a support between two sheets of Kapton foil. The application of Kapton foil prevents evaporation of reactive water during experiments and it prevents specimen carbonization [39]. Diffraction patterns were collected using gonio scan with a step size of 0.0263 • and a scanning angle ( • 2Theta) from 4 to 70 • .…”

Section: Structure Changes During Cement Hydration Followed By Using ...mentioning

confidence: 99%

The Influence of GGBFS as an Additive Replacement on the Kinetics of Cement Hydration and the Mechanical Properties of Cement Mortars

Jozić,

Ljubičić,

Petrović

et al. 2023

Buildings

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Granulated blast furnace slag (GBFS) is a byproduct of the iron production process. The objective of this study is to determine the effects of ground granulated blast furnace slag (GGBFS), used as a replacement admixture (0–40 wt.%) for ordinary Portland cement (OPC), on the setting time, the heat of hydration, and the mechanical properties of cement mortar. The influence of GGBFS as a replacement additive on the setting time shows that it has an accelerating effect on cement hydration. Calorimetric measurements were performed on the cement paste system to determine the effects of GGBFS on the hydration of OPC. Calorimetric measurements carried out show that the replacement of GGBFS in an amount up to 40 wt.% reduces the total heat of hydration by up to 26.36% compared to the reference specimen. The kinetic analysis performed on the calorimetric data confirms the role of GGBFS as an accelerator by shortening the time during which the process of nucleation and growth (NG), as the most active part of hydration, is reduced up to 2.5 h. The value of the Avrami–Erofee constant indicates polydispersity and heterogeneous crystallization. Mechanical tests of cement mortars were performed after 3, 7, 14, 28, 70, and 90 days of hydration and showed that replacement addition of GGBFS slightly reduced the mechanical properties in the early phase of hydration, while in the later phase of hydration it contributed to an increase in the mechanical properties.

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In-situ laboratory X-ray diffraction applied to assess cement hydration

Cited by 33 publications

References 160 publications

Carbon Emission Evaluation of CO2 Curing in Vibro-Compacted Precast Concrete Made with Recycled Aggregates

Carbon Emission Evaluation of CO2 Curing in Vibro-Compacted Precast Concrete Made with Recycled Aggregates

Structural Characteristics and Cementitious Behavior of Magnesium Slag in Comparison with Granulated Blast Furnace Slag

The Influence of GGBFS as an Additive Replacement on the Kinetics of Cement Hydration and the Mechanical Properties of Cement Mortars

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