Deteriorated hardened cement paste structure analyzed by XPS and 29Si NMR techniques

Kurumisawa, Kiyofumi; Nawa, Toyoharu; Owada, Hitoshi; Shibata, Masahito

doi:10.1016/j.cemconres.2013.07.003

Cited by 64 publications

(21 citation statements)

References 44 publications

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“…Figure illustrates the chemical shift in the reference and the white‐zone sample. As expected, in the reference sample only

Q^{1}

(chain end) and

Q^{2}

(within chain) peaks were visible, and neither

Q^{3}

Q^{4}

were observed, since chain structures were the major constituents in HCP . However, in the white zone, clear

Q^{3}

and

Q^{4}

peaks were observed, which indicated that branched and networked structures were formed due to a high degree of calcium depletion.…”

Section: Resultssupporting

confidence: 63%

“…It is well‐established that a 29 Si spectrum of the silicate anion is represented in the range of −70 to −76 ppm for

Q^{0}

(monomer), −78 for

Q^{1}

(dimer or end group in a chain), −81 to −85 for

Q^{2}

(chain), −93 to −102 for

Q^{3}

(branched structure), and −107 to −115 for

Q^{4}

(networked structure) . The average degree of C‐S‐H connectivity

true \overset{n}{true}

is calculated as follows,

\bar{n} = \frac{Q^{1} + 2 Q^{2} + 3 Q^{3}}{Q^{1} + Q^{2} + Q^{3}} .

…”

Section: Methodsmentioning

confidence: 99%

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Effect of the paste–anode interface under impressed current cathodic protection in concrete structures

Zhang

Tang

Bernin³

et al. 2018

Materials & Corrosion

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Impressed current cathodic protection (ICCP) is a powerful method to prevent and stop corrosion of steel in concrete structures. To evaluate the long‐term effect of ICCP, accelerated tests have been adopted using high current densities. A carbon fiber reinforced polymer mesh was introduced as anode. The presented research focused on the changes at the paste–anode interface as a consequence of applying current. The treated samples were characterized by various techniques. Calcium dissolution was found with an average thickness of 0.34 mm around the anode after charges of 6 × 106 C/m2 were applied, equivalent to applying 4 mA/m2 of anode surface for 30 years. Calcium dissolution resulted in a white zone around the anode, where the calcium silica ratio was lowered and almost no crystal phase was observed. NMR results show clear Q3 and Q4 peaks in the white zone, which contained extended branched and networked structures of hardened cement paste. An increased resistance caused by the formation of the white zone may eventually make the system fail because of insufficient current densities. CFRP has been proven suitable for ICCP application even at a current density of 4 A/m2 of anode surface.

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“…Figure illustrates the chemical shift in the reference and the white‐zone sample. As expected, in the reference sample only

Q^{1}

(chain end) and

Q^{2}

(within chain) peaks were visible, and neither

Q^{3}

Q^{4}

were observed, since chain structures were the major constituents in HCP . However, in the white zone, clear

Q^{3}

and

Q^{4}

peaks were observed, which indicated that branched and networked structures were formed due to a high degree of calcium depletion.…”

Section: Resultssupporting

confidence: 63%

“…It is well‐established that a 29 Si spectrum of the silicate anion is represented in the range of −70 to −76 ppm for

Q^{0}

(monomer), −78 for

Q^{1}

(dimer or end group in a chain), −81 to −85 for

Q^{2}

(chain), −93 to −102 for

Q^{3}

(branched structure), and −107 to −115 for

Q^{4}

(networked structure) . The average degree of C‐S‐H connectivity

true \overset{n}{true}

is calculated as follows,

\bar{n} = \frac{Q^{1} + 2 Q^{2} + 3 Q^{3}}{Q^{1} + Q^{2} + Q^{3}} .

…”

Section: Methodsmentioning

confidence: 99%

Effect of the paste–anode interface under impressed current cathodic protection in concrete structures

Zhang

Tang

Bernin³

et al. 2018

Materials & Corrosion

View full text Add to dashboard Cite

show abstract

“…This could be verified by the XPS analysis (Figure and Table S5). The increased binding energies of Si 2p in C0 and C3 as compared with C 3 S implied the higher degree in the polymerization of C–S–H gel after hydration of C 3 S . Considering that Ca 2+ could be coordinated with COO − replacing partial Na + and the structure of the guluronate blocks in SA allowed a high degree of coordination of Ca 2+ , the binding energy of COO − ···Ca 2+ bond was stronger than that of ironic COO − ···Na + bond, causing that the electron cloud density of O=C−O in COO − ···Ca 2+ tended to average as compared with that in COO − ···Na + .…”

Section: Discussionmentioning

confidence: 99%

Design of novel organic–inorganic composite bone cements with high compressive strength, in vitro bioactivity and cytocompatibility

Ding

Chen

et al. 2019

J Biomed Mater Res

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In this work, novel bioactive organic–inorganic composite bone cements consisting of tricalcium silicate (C3S), sodium alginate (SA), and calcium sulfate hemihydrate (CS) were successfully fabricated for the first time via a special method designing material composition and internal structure simultaneously, which was intended to enhance mechanical performance by combining progressive hydration process of C3S with distinctive gelation capacity of SA and further improve degradability and self‐setting properties with the addition of CS. Depending on the synergistic combination of hydration and gelation, the C3S/SA/CS composite cements (45/45/10 wt %) obtained extremely higher compressive strength up to 92.41 MPa as compared with each single component. The reinforcing mechanisms involving interfacial interaction and interior microstructure were proposed to explain this enhancement phenomenon. Additionally, the final setting time could be reduced from 68 min to 21 min with the increasing CS content. The composite cements possessed good apatite mineralization ability in simulated body fluid solution and moderate degradation rate in phosphate buffer solution. What's more, the composite cements exhibited excellent cytocompatibility and increased proliferation of rat bone‐marrow stem cells. This study could provide guidelines for the preparation of bioactive composite cements with enhanced mechanical performance, which may be suitable for load‐bearing bone repair. © 2019 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 107B: 2365–2377, 2019.

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“…Fig. 3(b) displays the peak-fitted Ca 2p signals from PA0.0 (the red dotted line is the curve fitting results) [20]. All the Ca 2p spectra exhibited complex structures, with two main peaks centered at 346.9 eV and 350.3 eV, respectively.…”

Section: Xps Analysismentioning

confidence: 97%

Research on the chemical mechanism in the polyacrylate latex modified cement system

Wang

Zheng

et al. 2015

Cement and Concrete Research

114

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Deteriorated hardened cement paste structure analyzed by XPS and 29Si NMR techniques

Cited by 64 publications

References 44 publications

Effect of the paste–anode interface under impressed current cathodic protection in concrete structures

Effect of the paste–anode interface under impressed current cathodic protection in concrete structures

Design of novel organic–inorganic composite bone cements with high compressive strength, in vitro bioactivity and cytocompatibility

Research on the chemical mechanism in the polyacrylate latex modified cement system

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