Changes in mineral composition, growth of calcite crystal, and promotion of physico-chemical properties induced by carbonation of β-C2S

Wang, Dan; Fang, Yang; Zhang, Yangyang; Chang, Jun

doi:10.1016/j.jcou.2019.06.005

Cited by 130 publications

(33 citation statements)

References 60 publications

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“…And the smaller sized carbonates would normally exhibit a high hardness and mechanical strength (Hu et al, 2010). Furthermore, the freshly formed carbonated with a smaller crystal size would also grow, leading to the interlocking among the carbonates (Wang et al, 2019a), as also shown in Figure 10, both of which can contribute to the compressive strength.…”

Section: Resultsmentioning

confidence: 98%

“…29 Si MAS-NMR measurements were used to investigate the structure of C-S-H gel formed during the hydration of ODD and OSD samples, and Figure 8 shows the 29 Si MAS-NMR spectra of ODD and OSD pastes at 28 days. Generally, the 29 Si MAS-NMR spectra in the OPC pastes shows different signals of Q n structural units, approximately (i) −68 to −75 ppm corresponding to the Q 0 , (ii) −76 to −82 ppm corresponding to the Q 1 , (iii) −82 to −88 ppm corresponding to the Q 2 , (iv) −88 to −98 ppm corresponding to the Q 3 , and (v) −98 to −120 ppm (Da Silva Andrade et al, 2019; Wang et al, 2019a, 2019b).…”

Section: Resultsmentioning

confidence: 99%

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Mechanism of strength evolution of seawater OPC pastes

Zhang

Sun

Zheng

et al. 2021

Advances in Structural Engineering

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This work investigated the strength degradation mechanisms of seawater ordinary Portland cement (OPC) pastes. Two types of specimens were prepared ((i) OSD sample (i.e. OPC was mixed with seawater, and then cured in deionized (DI) water) and (ii) ODD sample (i.e. OPC was mixed with DI water, and then cured in DI water, as the reference system)). The use of seawater in preparing OPC pastes effectively increased the hydration rate and early-age mechanical strength, but lowered the mechanical strength at the later age. The higher hydration degree and larger amounts of carbonates with a smaller crystal size enabled the seawater OPC pastes to exhibit a higher early-age mechanical strength, increasing by 13.0%–17.0% compared with the DI water OPC pastes. While the formation of Friedel’s salt and the formation of calcium-silicate-hydrate (C-S-H) gel with a lower polymerization degree and mean molecular chain length resulted in the deterioration of the pore structure and negatively affected the later-age strength development of the seawater OPC paste, decreasing by 5.8%–11.9% compared with the DI water OPC pastes.

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Section: Resultsmentioning

confidence: 98%

Section: Resultsmentioning

confidence: 99%

Mechanism of strength evolution of seawater OPC pastes

Zhang

Sun

Zheng

et al. 2021

Advances in Structural Engineering

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“…In steel slag matrix, the CaCO 3 minerals are expected to present a strong C–O vibration band in 731 cm −1 (calcite or aragonite) [ 35 ], 874 cm −1 (calcite) [ 36 , 37 ], and around 1420 cm −1 (calcite) [ 37 , 38 ]. And the Si–O asymmetric stretching vibration band around 520 and 975 cm −1 were related to β-C 2 S [ 37 ] and C–S–H [ 35 ]. And a weak stretching vibration band at 795 cm −1 could be assigned to quartz or amorphous SiO 2 [ 39 ].…”

Section: Resultsmentioning

confidence: 99%

“…The vibrations at 874 and 1420 cm −1 were assigned to the presence of calcite. The broad peak in 1420 cm −1 was due to the appearance of amorphous calcium carbonate (ACC, CaCO 3 ·nH 2 O) [ 28 , 37 , 40 ]. HSZ0-1d and HSZ15-14d had sharper calcite peaks than HSZ0-14d and HSZ15-1d in 1420 cm −1 .…”

Section: Resultsmentioning

confidence: 99%

Effect of Different Hydration Time on Carbonation Degree and Strength of Steel Slag Specimens Containing Zeolite

Zhang

Chang

2020

Materials

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Steel slag partially substituted by zeolite (SZ) was beneficial for improving the compressive strength and carbonation degree of SZ specimens after a combined curing (hydration and then carbonation) process due to pozzolanic reaction between them. By previous work results, the zeolitic substitution ratios of 5 wt.% and 15 wt.% in steel slag specimens (SZ5 and SZ15) gained the optimum compressive strength and carbonation degree, respectively, after 1 day hydration and then 2 h carbonation. This study investigated the effect of previous hydration time (1, 3, 7, 14, and 196 days) on carbonation degree and strength of SZ specimens after subsequent carbonation curing. Two zeolitic substitution ratios (5 wt.% and 15 wt.%) were selected and pure steel slag specimens were also prepared as controls. Compressive strength results revealed that the optimum hydration curing time was 1 day and the optimum zeolitic substitution ratio was 5 wt.%. The pozzolanic reaction happened in SZ specimens was divided into early and late pozzolanic reaction. In the late hydration, a new mineral, monocarboaluminate (AFmc) was produced in SZ15 specimens, modifying the carbonation degree and strength further. And the mechanism of pozzolanic reaction in early and late hydration in SZ specimens was explained by several microscopic test methods.

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“…Along with the carbonation reaction, new peaks at around − 101 and − 111 ppm appeared. The peak at − 101 ppm is attributed to the hydroxylated surface sites of the silica gel and is assigned to Q 3 species, while the peak at − 111 ppm is attributed to the Q 4 sites of a polymerized 3D network of the silicate tetrahedrons 18,32,33 . Ashraf et al 7 suggests that the presence of cross linked Q 3 species indicates that the silica gel formed after the carbonation reaction is a Ca-modified silica gel.…”

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confidence: 99%

Carbonated rankinite binder: effect of curing parameters on microstructure, strength development and durability performance

Smigelskyte

Šiaučiūnas

Hilbig

et al. 2020

Sci Rep

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Due to the high CO 2-footprint of ordinary Portland cement (OPC), the search for alternative binders is now in a full swing. Rankinite-which is a hydraulically inactive material and low in calcium, is a real alternative to OPC, as it absorbs the harmful greenhouse gas from the air through carbonation hardening. Nevertheless, the carbonation hardening has not yet been fully clarified and sufficiently investigated. In this study we show that rankinite achieves a final strength exceeding 100 MPa at 45 °C and 24 h, whereby the binder is only ~ 50% carbonated. The reaction is diffusion limited while a dense layer of carbonation products around the rankinite grains hinders a higher degree of carbonation. The carbonation reaction could be fully characterized by spatially resolved microanalysis such as LA-ICP-MS, NMR and XRD. Finally, durability tests show the excellent suitability of the rankinite binder for a wide range of applications, making it an attractive material not only from an environmental point of view. Concrete is the second largest processed commodity after water consumed annually by the population of Earth 1. Due to such vast demand for the building materials, ordinary Portland cement (OPC) industry is responsible for over 5% of global anthropogenic greenhouse gas emissions, with almost equal amount of CO 2 emitted to the atmosphere after production of one tonne of cement 2-4. Accordingly, the scientific community is struggling to find the solutions for greenhouse gas mitigation and reduction of the negative effect of the cement production. Even though, in the past decades many options to alleviate the adverse effect of OPC production to the environment were proposed 5 , however, recent studies have shown that strategies like clinker substitutions, alternative fuels and/or improved energy efficiency alone will not be sufficient enough to meet the target CO 2 reductions 6. Thus, finding alternative cementitious materials with lower CO 2 footprint than OPC is one the major challenges for the building material industry and the scientific community. At the moment, one of the most promising approaches is the production of low-lime calcium silicate cement (CSC) 7-11. This type of binding material not only requires lower amounts of limestone but also has lower production temperature, thereby resulting in much lower CO 2 emissions 12. Moreover, such binders are environmentally amicable not only due to lower CO 2 emissions, but also for the ability to permanently store CO 2 in the concrete structure in their carbonation hardening process 13. Implementation of such efficient carbonation technologies can potentially lead to cementitious materials becoming one of the largest global CO 2 sequestration sectors 14. Rankinite-Ca 3 Si 2 O 7-is one of such low lime calcium silicates that can be used as an alternative binder that gained more interest recently 7,15,16. Since the CaO/SiO 2 ratio of rankinite is almost twice lower than of ordinary cement, thus it requires lower amounts of calcareous raw materials. The fuel and...

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Changes in mineral composition, growth of calcite crystal, and promotion of physico-chemical properties induced by carbonation of β-C2S

Cited by 130 publications

References 60 publications

Mechanism of strength evolution of seawater OPC pastes

Mechanism of strength evolution of seawater OPC pastes

Effect of Different Hydration Time on Carbonation Degree and Strength of Steel Slag Specimens Containing Zeolite

Carbonated rankinite binder: effect of curing parameters on microstructure, strength development and durability performance

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