Relationship between NMR 29Si Chemical Shifts and FT-IR Wave Numbers in Calcium Silicates

Okada, Yoshihiko; Masuda, Takuro; Takada, Minori; Xu, Lingling; Mitsuda, Takeshi

doi:10.1007/978-3-642-80432-8_4

Cited by 13 publications

(10 citation statements)

References 12 publications

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“…5. The FTIR spectra of the hydrated cement paste are characterized by a large signal between 800 and 1200 cm −1 with the peak at 957 cm −1 which may be associated with the asymmetric stretching vibration ν 3 of Si-O bonds 38,39 . Similar data were obtained for hydrated C 3 S pastes 40,41 , where the peak between 967 and 954 cm −1 was associated with the asymmetric stretching vibration of Si-O bonds in the C-S-H gel Q 2 units.…”

Section: Results and Interpretationmentioning

confidence: 99%

Carbon Capture and Utilization by mineralization of cement pastes derived from recycled concrete

Skoček

Zając

Haha

2020

Sci Rep

116

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Reduction of co 2 emissions associated with cement production is challenging in view of the increasing cement demand and the fact that major part of the emissions originates from the main raw material used -limestone -which can be only to extremely low amount substituted. A carbon capture and Utilization (CCU) approach based on mineralization of fines derived from concrete appears to be a viable alternative to reduce these emissions. the co 2 sequestration and the reactivity of the obtained carbonated recycled fines is experimentally demonstrated for lab as well as industrial materials for different mineralization conditions. It is shown that all CO 2 originally released by limestone calcination during clinker production can be sequestered by the full carbonation of the fines within a short time. Upon full carbonation, gels with pozzolanic properties form in the fines irrespective of the conditions tested. The carbonated fines have specific CO 2 savings more than 30% higher than the simple clinker replacement by limestone.Global urbanization and economic development increase demand for new buildings and infrastructure and hence for concrete. Already now, concrete is the second most used substance by mass after water. Even though concrete has low specific CO 2 emissions below 150 kg CO2,eq /ton concrete 1 , its abundance makes it responsible for 5-8% of man-made CO 2 emissions 1-4 . Most of the concrete's emissions result from production of the main cement component, the clinker. Hence, focus of researchers as well as of cement producers has been on lowering the clinker content in cements and on improving the efficiency of clinker production. As summarized in 1 , both these approaches have already reached their potentials in mature economics. Almost all suitable Supplementary Cementitious Materials (SCMs) available are already used in cement and concrete production. For the clinker production, further energy efficiency improvements would have only a minor effect as the energy consumption approaches the lowest theoretical value and is often driven by additional objectives such as alternative fuels usage rate.Nevertheless, the cement industry needs to drastically reduce its emissions and at the same time satisfy the increasing cement demand of the global economy 5 . At the level of concrete structures and concrete applications, several approaches can bring considerable CO 2 savings. These include re-usable structures with extended service life or concretes with reduced cement contents 3,6 . At the level of cement production, extended use of calcined clays and limestone as SCM are the only approaches applicable at large enough scale. With the ongoing departure from coal-fired power plants and decreasing demand for pig iron in mature markets, the availability of blast furnace slags and fly ashes is expected to decrease. Calcined clays and limestone have the potential to replace these SCMs in the current market as well as provide sufficient volumes of SCMs in growing markets. However, clinker replacement by limestone o...

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Section: Results and Interpretationmentioning

confidence: 99%

Carbon Capture and Utilization by mineralization of cement pastes derived from recycled concrete

Skoček

Zając

Haha

2020

Sci Rep

116

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“…The exact and accurate structural analysis of calcium-silica gels based on the m 3 vibration of FTIR spectra can be complicated as m 3 causes a broad absorption band resulting from the overlapping of similar absorptions. However, the m 3 band shifts to higher wave number with increasing degree of polymerization of the silicate compound due to the increase of the bond strength of Si-O [58]. Thus, the exact positions of these bands are dependent on the calcium to silica (Ca/Si) atomic ratio of the calcium-silica gel phase as this ratio also represent the degree of silicate polymerization of the C-S-H [60].…”

Section: Fitr Spectroscopic Observationsmentioning

confidence: 95%

“…The FTIR spectra for silicate compounds usually exhibit a large absorption between 800 and 1200 cm -1 which correspond to the asymmetrical stretching vibration (m 3 ) of Si-O bond [31,49]. The absorption bands of calcium silicates at 800 cm -1 or below correspond to the out-of-plane skeletal (m 4 ) and in-plane skeletal (m 2 ) [58,59] vibrations of Si-O bond. In this study, the FTIR spectra were collected in the range of 800-4000 cm -1 , but the main focus was given on 800-1800 cm -1 region to understand the structure of the calcium-silica gel formed during the carbonation reaction of calcium silicate phases.…”

Section: Fitr Spectroscopic Observationsmentioning

confidence: 99%

Carbonation behavior of hydraulic and non-hydraulic calcium silicates: potential of utilizing low-lime calcium silicates in cement-based materials

2016

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This paper presents a study on the carbonation behaviors of hydraulic and nonhydraulic calcium silicate phases, including tricalcium silicate (3CaOÁSiO 2 or C 3 S), c-dicalcium silicate (c-2CaOÁSiO 2 or c-C 2 S), b-dicalcium silicate (b2CaOÁSiO 2 or b-C 2 S), rankinite (3CaOÁ2SiO 2 or C 3 S 2 ), and wollastonite (CaOÁSiO 2 or CS). These calcium silicate phases were subjected to carbonation reaction at different CO 2 concentration and temperatures. Thermogravimetric analysis (TGA) tests were performed to quantify the amounts of carbonates formed during the carbonation reactions, which were eventually used to monitor the degree of reactions of the calcium silicate phases. Both hydraulic and non-hydraulic calcium silicates demonstrated higher reaction rate in case of carbonation reaction than that of the hydration reaction. Under specific carbonation scenario, non-hydraulic low-lime calcium silicates such as c-C 2 S, C 3 S 2 and CS were found to achieve a reaction rate close to that of C 3 S. Fourier transformed infrared (FTIR) spectroscopy and scanning electron microscope (SEM) tests were performed to characterize the carbonation reaction products of the calcium silicate phases. The FTIR spectra during the early stage of carbonation reaction showed formation of calcium silicate hydrate (C-S-H) from C 3 S, c-C 2 S, b-C 2 S, and C 3 S 2 phases with a similar degree of polymerization as that of the C-S-H that forms during the hydration reaction of C 3 S. However, upon further exposure to CO 2 , these C-S-H phases decompose and eventually converted to calcium-modified (Ca-modified) silica gel phase with higher degree of silicate polymerization. Contradictorily, CS phase started forming Ca-modified silica gel phase even at the early stage of carbonation reaction. This paper also revealed the stoichiometry of the Ca-modified silica gel that formed during the carbonation reaction of the calcium silicate phases using the SEM/energy dispersive spectroscopy (EDS) and TGA results.

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“…Unfortunately, the structure corresponding to Q 2 L is not clear. The intensity of the Q 1 peak provides important information about the length of silicate chains in C-S-H. Usually, to discuss a sample's structure, previous works have calculated the sample's Q 2 /Q 1 ratios [6,7,11,12]. The Q n denotes the differences in connections of silicate tetrahedra (see Fig.…”

Section: Si Nmr Spectroscopymentioning

confidence: 99%

“…The differences in chemical shifts were assigned to the differences in connectivities of silicate tetrahedra. To represent the connectivities, the terms Q n (0 ≤ n ≤ 4) are often used, where n is the number of oxygens bridging adjacent tetrahedra [6,7,11,12]. That is, Q 0 corresponds to monomer silicates, Q 1 denotes end-groups and Q 2 represents middle groups in the silicate tetrahedral chains, as shown in Fig.…”

Section: Si Nmr Spectroscopymentioning

confidence: 99%

Structure alteration of C-S-H (calcium silicate hydrated phases) caused by sorption of caesium

Iwaida¹,

Nagasaki²,

Tanaka³

et al. 2002

Radiochimica Acta

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Cement / Caesium / Sodium / Sorption / XRD / 29 Si NMRSummary. The sorption behavior of Cs onto C-S-H (calcium silicate hydrated phases) was investigated by evaluating the effect of sorption on the C-S-H structure.The C-S-H have a tobermorite-type layer structure. Each layer consists of central calcium and oxygen atoms sandwiched by silicate tetrahedral chains. Additional calcium and water are located in interlayer zones. The XRD spectra showed that the tobermorite-type layer degraded and that the sorption of Cs made the fragments of layer intergrowths much smaller. The fragmentation of the tobermorite-type layer was observed for C-S-H in contact with CsCl solution or with CsOH solution, but not for the C-S-H in contact with Na solution. Furthermore, 29 Si NMR spectroscopy revealed that the sorption of Cs onto C-S-H induced cleavages of silicate chains in C-S-H. It was also suggested that the OH − ion contributed to breaking the silicate chains.

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Relationship between NMR 29Si Chemical Shifts and FT-IR Wave Numbers in Calcium Silicates

Cited by 13 publications

References 12 publications

Carbon Capture and Utilization by mineralization of cement pastes derived from recycled concrete

Carbon Capture and Utilization by mineralization of cement pastes derived from recycled concrete

Carbonation behavior of hydraulic and non-hydraulic calcium silicates: potential of utilizing low-lime calcium silicates in cement-based materials

Structure alteration of C-S-H (calcium silicate hydrated phases) caused by sorption of caesium

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