scholarly journals Chloride-Binding Capacity of Portland Cement Paste Blended with Synthesized CA2 (CaO·2Al2O3)

2018 ◽  
Vol 2018 ◽  
pp. 1-11 ◽  
Author(s):  
Yunsu Lee ◽  
Mingyun Kim ◽  
Zhengxin Chen ◽  
Hanseung Lee ◽  
Seungmin Lim
Keyword(s):  
Portland Cement ◽  
Cement Paste ◽  
Binding Capacity ◽  
Water Soluble ◽  
Chloride Binding ◽  
X Ray Diffraction ◽  
Total Chloride ◽  
X Ray ◽  
Isotherm Equation ◽  
Portland Cement Paste

A chloride-binding capacity is the major factor to mitigate the ingress of chloride into concrete. This paper presents the chloride-binding capacity of Portland cement paste containing synthesized CA2 (CaO·2Al2O3). The CA2 was synthesized in the high-temperature furnace and characterized by X-ray diffraction for inspecting the purity. The synthesized CA2 was substituted for Portland cement by 0%, 5%, and 10% by weight, and the NaCl solution was used as an internal chloride, which is assumed as a total chloride. The chloride-binding capacity of cement paste was calculated from a water-soluble chloride extraction method by the application of the Langmuir isotherm equation. And the hydration products were analyzed using X-ray diffraction and thermogravimetric analysis. We demonstrate that the CA2 increases an AFm phase in the Portland cement system, and the incorporation of CA2 consequently enhances the chloride-binding capacity of cement paste samples.

Performance of Chloride Binding by Aluminate Hydrates in Cement-Based Composite Materials

2012 ◽  
Vol 583 ◽  
pp. 211-214
Author(s):  
Mi Feng Gou ◽  
Xue Mao Guan
Keyword(s):  
Composite Materials ◽  
Chemical Interaction ◽  
Binding Capacity ◽  
Freundlich Isotherm ◽  
Water Soluble ◽  
Chloride Binding ◽  
Test Results ◽  
X Ray Diffraction ◽  
Total Chloride ◽  
Free Chloride

The chloride binding capacity of aluminate hydrates in cement-based composite materials is investigated. The total chloride contents and free chloride contents were analyzed by acid-soluble method and water-soluble method. The chemical interaction of chloride with the hydrates of aluminate phases in cement was also studied by X-ray diffraction. Test results show that the monosulfate hydrate has chloride binding capacities, whereas ettringite has no capacity to bind chloride. The chloride binding by monosulfate hydrate is attributed to the formation of Friedel’s salt and Kuzel’s salt by the ion exchange of SO42- with Cl- and the nonlinear relationship can be represented best by a Freundlich isotherm.

scholarly journals Effects of Highly Crystalized Nano C-S-H Particles on Performances of Portland Cement Paste and Its Mechanism

Crystals ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 816
Author(s):  
Yuli Wang ◽  
Huijuan Lu ◽  
Junjie Wang ◽  
Hang He
Keyword(s):  
Portland Cement ◽  
Cement Paste ◽  
Setting Time ◽  
Tricalcium Silicate ◽  
Strength Development ◽  
Early Age ◽  
Hydration Products ◽  
X Ray ◽  
Early Strength ◽  
Portland Cement Paste

In order to improve the early age strength of ordinary Portland cement-based materials, many early strength agents were applied in different conditions. Different from previous research, the nano calcium silicate hydrate (C-S-H) particles used in this study were synthesized through the chemical reaction of CaO, SiO2, and H2O under 120 °C using the hydrothermal method, and the prepared nano C-S-H particles were highly crystalized. The influences of different amounts of nano C-S-H particles (0%, 0.5%, 1%, 2% and 3% by weight of cement) on the setting time, compressive strength, and hydration heat of cement paste were studied. The hydration products and microstructure of the cement paste with different additions of nano C-S-H particles were investigated through thermogravimetry-differential thermal analysis (TG-DTA), X-ray powder diffraction (XRD), and scanning electron microscope (SEM) tests. The results show that the nano C-S-H particles could be used as an early strength agent, and the early strength of cement paste can be increased by up to 43% through accelerating the hydration of tricalcium silicate (C3S). However, the addition of more than 2% nano C-S-H particles was unfavorable to the later strength development due to more space being left during the initial accelerated hydration process. It is suggested that the suitable content of the nano C-S-H particles is 0.5%−1% by weight of cement.

Mapping the Distribution of Corrosion Products in Cement Exposed to Sulfate using Energy Dispersive X-ray Diffraction

2001 ◽  
Vol 678 ◽  
Author(s):  
Angus P. Wilkinson ◽  
Cora Lind ◽  
Stuart R. Stock ◽  
Kimberly E. Kurtis ◽  
Nikhila Naik ◽  
...  
Keyword(s):  
Surface Layer ◽  
Calcium Carbonate ◽  
Cement Paste ◽  
Test Specimen ◽  
Sulfate Attack ◽  
Energy Dispersive ◽  
Type I ◽  
X Ray Diffraction ◽  
X Ray ◽  
Portland Cement Paste

AbstractThe use of energy dispersive X-ray diffraction (EDXRD) to produce 1 D maps of the phases present inside both an alumina-aluminum test specimen and a 1.0 cm diameter cylinder of type I portland cement paste is discussed. The surface of the cement paste sample was found to be rich in calcium carbonate and deficient in portlandite relative to the bulk. After 7 days exposure to 1000 ppm Na2SO4 there was no evidence for the formation of a surface layer rich in crystalline sulfate containing phases. EDXRD appears to be a powerful tool for the study of sulfate attack on portland cements.

Impact of the associated cation on chloride binding of Portland cement paste

2015 ◽  
Vol 68 ◽  
pp. 196-202 ◽  
Author(s):  
K. De Weerdt ◽  
A. Colombo ◽  
L. Coppola ◽  
H. Justnes ◽  
M.R. Geiker
Keyword(s):  
Portland Cement ◽  
Cement Paste ◽  
Chloride Binding ◽  
Portland Cement Paste

scholarly journals Influence of Polyethylene Terephthalate Powder on Hydration of Portland Cement

Polymers ◽  
2021 ◽  
Vol 13 (15) ◽  
pp. 2551
Author(s):  
Min Ook Kim ◽  
Jun Kil Park ◽  
Taek Hee Han ◽  
Joonho Seo ◽  
Solmoi Park
Keyword(s):  
Portland Cement ◽  
Polyethylene Terephthalate ◽  
Cement Paste ◽  
Pore Solution ◽  
Isothermal Calorimetry ◽  
Test Results ◽  
X Ray Diffraction ◽  
Replacement Ratio ◽  
Chemical Changes ◽  
X Ray

The management of plastic waste is a massive challenge and the recycling of plastics for newer applications is a potential solution. This study investigates the feasibility of using polyethylene terephthalate (PET) powder in cementitious composites. The changes in the strength and microstructure of Portland cement incorporating PET powder with different replacement ratios were systematically analyzed through the measurements of compressive strength, isothermal calorimetry, X-ray diffraction, thermogravimetric analysis, and Raman spectroscopy. In addition, the possible chemical changes of cement paste samples were studied upon exposure to different conditions, including deionized water, seawater, and simulated pore solution. Based on the test results and analysis, no apparent chemical changes were observed in the cement paste samples, regardless of the exposure conditions. In contrast, the PET powder incorporated into concrete exhibited remarkable changes, which may have occurred during the mixing process. The results also suggested that the maximum replacement ratio of PET powder should be less than 10% of the binder (by mass) to minimize its influence on cement hydration, due to the interaction between water and PET. The PET-containing samples showed the presence of calcium aluminate hydrates which were absent in the neat paste sample.

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