The impacts of sodium nitrate on hydration and microstructure of Portland cement and the leaching behavior of Sr2+

Zheng, Zhao; Li, Yuxiang; Zhang, Zuhua; Xue, Ming

doi:10.1016/j.jhazmat.2019.121805

Cited by 35 publications

(25 citation statements)

References 50 publications

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“…When the magnesium ions were doped, the C‐M‐S‐H phases had the same characteristic peaks as C‐S‐H, suggesting that the incorporation of magnesium ions into C‐S‐H had no significant influence on its semi‐crystalline structure. The characteristic peak of a few residual sodium nitrates in the samples overlapped with the characteristic peak of C‐M‐S‐H at 2θ of 29° 34 . Even so, the crystallinity of C‐M‐S‐H can be inferred according to the characteristic peak of C‐M‐S‐H at 2θ of 50°.…”

Section: Resultsmentioning

confidence: 85%

Calcium‐silicate‐hydrates/polycarboxylate ether nanocomposites doped by magnesium: Enhanced stability and accelerating effect on cement hydration

et al. 2022

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C‐S‐H/PCE (calcium‐silicate‐hydrates/polycarboxylate ether) nanocomposites have a significant accelerating effect on early hydration and early strength development of cementitious materials. In this study, magnesium ions are doped into C‐S‐H/PCE nanocomposites, and it is found that C‐S‐H/PCE nanocomposites doped by appropriate magnesium ions have much better stability. Besides, the accelerating effects of the modified nanocomposites on early cement hydration also get improved. The doped magnesium ions displace calcium ions and promote the absorption of PCE. Moreover, the incorporation of magnesium ions results in two unique morphologies of nanocomposites, that is, globule and gel. The globules are semi‐crystalline similar to C‐S‐H, while the gels are amorphous and have more branched silicate chains.

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Section: Resultsmentioning

confidence: 85%

Calcium‐silicate‐hydrates/polycarboxylate ether nanocomposites doped by magnesium: Enhanced stability and accelerating effect on cement hydration

et al. 2022

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“…In a previous study, a cement paste with LRM neutralized by sulfuric acid had a compressive strength ratio of less than 90% after 1 day of aging [ 16 ], while our LRMN samples neutralized by nitric acid had a higher strength than the Plain sample. This is attributed to the accelerated hydration and highly developed strength in the presence of NaNO 3 , which was generated by the nitric acid neutralization of LRM, as confirmed by the XRD results in Figure 3 [ 19 ].…”

Section: Resultsmentioning

confidence: 85%

“…In addition, the XRD analysis results are in agreement with the compressive strength results shown in Figure 4 , the hydration results of C3S and C2S, and the formation of C–S–H and portlandite (as shown in Figure 6 c). NaNO 3 accelerates hydration [ 19 ] and promotes the development of the strength, as confirmed by the compressive strength results of the cement paste with LRM + N after 1 day of aging. Furthermore, the hydration progressed faster as portlandite started to appear after 28 days of hydration, portlandite and C–S–H promote the strength of all samples.…”

Section: Resultsmentioning

confidence: 88%

“…Nitrates, such as calcium nitrate (Ca(NO 3 ) 2 ) and sodium nitrate (NaNO 3 ), are often used as hardening accelerators to improve the initial strength of cement [ 17 , 18 ]. Sufficient quantities of sodium nitrate promote the hydration of solidified cement matrices during the pre-induction period and shorten the acceleration period [ 19 ].…”

Section: Introductionmentioning

confidence: 99%

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Hydration Properties of Cement with Liquefied Red Mud Neutralized by Nitric Acid

Kang

Hye-Ju

Lee³

2021

Materials

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An increasing amount of red mud (RM) is being generated globally due to the growth in aluminum production. To avoid RM pollution, low-cost methods for effectively recycling RM are being investigated. We propose a method for recycling RM as a construction material. Liquefied RM (LRM) was neutralized by nitric acid and added to cement paste, and the hydration heat, compressive strength, and hydration products were investigated. The cement paste with neutralized LRM had a higher compressive strength than that of plain cement paste and cement paste with LRM without neutralization at 1 day of aging; this indicates that nitric acid neutralization increases the early-age strength. Furthermore, the cement paste with 10% neutralized LRM showed 28 days-compressive strength and hydration heating curves similar to the plain mixture, indicating the positive impact of LRM neutralization on the strength. It was noted that a greater quantity of portlandite was produced earlier in cement paste with neutralized LRM than in that without. Therefore, the proposed method of using RM as a concrete additive has the potential to reduce the cost and environmental impact of both construction materials and RM waste management.

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“…Radioactive wastes, such as ILW and LLW, produced from decommissioning processes are disposed in near-surface facilities and landfills to isolate these wastes from the natural ecosystem for sufficient periods of time [6][7][8]. To ensure safe disposal, fluidizable radioactive wastes such as concentrated wastes, spent resins, sludge, and dry active wastes must be solidified or immobilized homogeneously to limit the release of radionuclides and maintain the structural integrity of the disposal environment [9].…”

Section: Introductionmentioning

confidence: 99%

Leaching Behavior of Cesium, Strontium, Cobalt, and Europium from Immobilized Cement Matrix

Goo

Kim

Kang³

et al. 2021

Applied Sciences

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Numerous low-level and intermediate-level radioactive wastes are generated from the decommissioning processes of nuclear power plants; these wastes are immobilized to prevent the release of radionuclides under disposal conditions. In this study, we investigated the leaching behavior of Cs, Sr, Co, and Eu, which are common in immobilized decommissioning wastes. Ordinary Portland cement (OPC) was used as an immobilization agent. During the test, leaching of the nuclides occurred in the order of Cs, Sr, Co, and Eu and decreased over time. The results showed that 41.4% of the total Cs leached over 90 days, although the other elements leached in quantities less than 1.5%. CaCO3 was precipitated by the release of cementitious materials, indicating carbonation of the leachate. The leachability indexes in all cases exceeded the acceptable criteria (>6). The results of the present study suggest that OPC can be effectively used as a binding material to immobilize nuclides (Cs, Sr, Co, and Eu) contained in decommissioning wastes.

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The impacts of sodium nitrate on hydration and microstructure of Portland cement and the leaching behavior of Sr2+

Cited by 35 publications

References 50 publications

Calcium‐silicate‐hydrates/polycarboxylate ether nanocomposites doped by magnesium: Enhanced stability and accelerating effect on cement hydration

Calcium‐silicate‐hydrates/polycarboxylate ether nanocomposites doped by magnesium: Enhanced stability and accelerating effect on cement hydration

Hydration Properties of Cement with Liquefied Red Mud Neutralized by Nitric Acid

Leaching Behavior of Cesium, Strontium, Cobalt, and Europium from Immobilized Cement Matrix

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