Strength and Leaching Characteristics of Magnesium Phosphate Cement-Solidified Zinc- Contaminated Soil under the Effect of Acid Rain

Xu, Song; Wu, Xuehui; Cai, Yuanqiang; Ding, Yaokun; Wang, Zhe

doi:10.1080/15320383.2018.1438364

Cited by 17 publications

(10 citation statements)

References 20 publications

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“…The advantages of MKP cements include fast setting [9,26,27], high early strength [9,[27][28][29], low shrinkage [9,29,30], and strong bonding with Portland cement concrete substrates [9,10,31,32]. MKP cements have been used as rehabilitation materials [9,31,32], as stabilization/solidification agents for immobilizing wastes containing heavy metals [33][34][35][36], and been considered as potential binders for conditioning low-level nuclear wastes [3,[37][38][39][40][41][42][43]. Recent research involved also the use in medical technology due to their good biocompatibility and antibacterial properties [44,45].…”

Section: Introductionmentioning

confidence: 99%

Influence of magnesium-to-phosphate ratio and water-to-cement ratio on hydration and properties of magnesium potassium phosphate cements

Winnefeld

Kaufmann

et al. 2019

Cement and Concrete Research

134

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Magnesium-to-phosphate (Mg/PO4) and water-to-cement (w/c) ratios are important 9 factors controlling hydration and properties of magnesium potassium phosphate (MKP) cements.This study investigated the influence of Mg/PO4 molar ratios (2.7, 4 and 8) and w/c (0.25 and 5) on cement hydration, compressive strength and volume stability. Low w/c ratio slowed down cement hydration at lower Mg/PO4 beyond 1 day, and prevented the precipitation of intermediate hydrates at higher Mg/PO4. At lower Mg/PO4 expansion and strength loss were observed with time due to the continuing hydration within the already hardened cement. Higher Mg/PO4 resulted in faster hydration, higher strength, and in the precipitation of traces of brucite, which had no significant influence on the long-term volume stability and strength. Therefore, moderate Mg/PO4 molar ratios between 4 and 8 depending on w/c ratio used are recommended for the production of MKP cements with robust performance.

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Section: Introductionmentioning

confidence: 99%

Influence of magnesium-to-phosphate ratio and water-to-cement ratio on hydration and properties of magnesium potassium phosphate cements

Winnefeld

Kaufmann

et al. 2019

Cement and Concrete Research

134

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“…In addition to its sustainable nature, MPC possesses the properties of fast setting, high early-stage strength, low shrinkage, and excellent compatibility with impurities and contaminants due to its strong chemical stability and high bonding strength. , These advantages make MPC a high-performance S/S material in hazardous waste treatment ( e.g. , PTEs contaminated soil/sediment and radioactive waste). ,, In previous research, the long-term stability of the MPC-treated Zn-rich waste has been comprehensively investigated by different leaching schemes. , When exposed to the radical conditions ( e.g. , acid rain environment), MPC-treated groups can provide lower PTEs leachability than cement-based groups .…”

Section: Introductionmentioning

confidence: 99%

Designing Magnesium Phosphate Cement for Stabilization/Solidification of Zn-Rich Electroplating Sludge

Zhang

Wan

Wang

et al. 2022

Environ. Sci. Technol.

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Electroplating sludge is a hazardous waste due to its high potential to leach toxic elements into the natural environment. To alleviate this issue, we tailored magnesium phosphate cement (MPC) as a low-carbon material for stabilization/solidification (S/S) of Zn-rich electroplating sludge. The interaction between MPC and ZnO was investigated to clarify the precipitate chemistry, microstructure transition, and chemical environment of Zn species in the MPC-treated Zn sludge system. Comprehensive characterization (by X-ray diffraction (XRD), 31P nuclear magnetic resonance (NMR), and extended X-ray absorption fine structure spectroscopy (EXAFS)) and thermodynamic modeling results revealed that the incorporated ZnO preferentially reacted with phosphate to form Zn3(PO4)2·2H2O/Zn3(PO4)2·4H2O, changing the orthophosphate environment in the MPC system. Stronger chemical bonding between Zn and phosphate in comparison to the bonding between Mg and phosphate also resulted in the formation of amorphous Zn3(PO4)2·2H2O/Zn3(PO4)2·4H2O. Zn3(PO4)2·4H2O precipitate appears to predominate at high {K+}{H+}{HPO4 2–} values, and the formation of Zn3(PO4)2·2H2O/Zn3(PO4)2·4H2O competed for the Mg sites in the MPC system, leading to the inhibition of formation of Mg–phosphate precipitates. Overall, this work uncovers the precipitate chemistry and microstructure transition of Zn species in the MPC system, providing new insights into the sustainable S/S of Zn-contaminated wastes by adopting MPC.

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“…On the other hand, researches, done by Aldaood et al [32], Du et al [33], Li et al [34], Zaimoglu [35], and Xu et al [36], showed that extreme environmental changes, such as freeze-thaw cycles, high-salt groundwater, acid rain infiltration, or dry-wet alternation, could result in changes in the properties of solidified contaminated soils and even cause the S/S to fail. Regions in China subjected to freezing are widely distributed: For example, permafrost regions accounts for approximately 21.5% of the total land area, seasonal frozen soil regions about 53.5%, transient frozen soil regions approximately 23.9%, and frozen soil-free regions only 1.1% according to the report by Xia [37].…”

Section: Introductionmentioning

confidence: 99%

Influence of Freeze–Thaw Cycles and Binder Dosage on the Engineering Properties of Compound Solidified/Stabilized Lead-Contaminated Soils

Zhong

Wang

et al. 2020

IJERPH

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The solidification/stabilization (S/S) method is the usual technique for the remediation of soils polluted by heavy metal in recent years. However, freeze-thaw cycles, an important physical process producing weathering of materials, will affect the long-term stability of engineering characteristics in solidified contaminated soil. In addition, it is still questionable whether using large dosages of binders can enhance the engineering properties of solidified/stabilized contaminated soils. In this study, the three most commonly used binders (i.e., cement, quicklime, and fly ash), alone and mixed in different ratios, were thus added to lead-contaminated soil in various dosages, making a series of cured lead-contaminated soils with different dosages of binders. Afterward, unconfined compression strength tests, direct shear tests, and permeability tests were employed on the resulting samples to find the unconfined compressive strength (UCS), secant modulus (E 50 ), internal friction angle (ϕ), cohesion (c), and permeability coefficient (k) of each solidified/stabilized lead-contaminated soil after 0, 3, 7, and 14 days of freeze-thaw cycles. This procedure was aimed at evaluating the influence of freeze-thaw cycle and binder dosage on engineering properties of solidified/stabilized lead-contaminated soils. Results of our experiments showed that cement/quicklime/fly ash could remediate lead-contaminated soils. However, it did not mean that the more the dosage of binder, the better the curing effect. There was a critical dosage. Excessive cementation of contaminated soils caused by too much binder would result in loss of strength and an increase in permeability. Furthermore, it was found that UCS, E 50 , ϕ, c, and k values generally decreased with the increase in freeze-thaw cycle time-a deterioration effect on the engineering characteristics of solidified lead-contaminated soils. Avoiding excessive cementation, 2.5% cement or quicklime was favorable for the value of E 50 while a 2.5% fly ash additive was beneficial for the k value. It is also suggested that if the freeze-thaw cycle continues beyond the period supported by excessive cementation, such a cycle will rapidly destroy the original structure of the soil and create large cracks, leading to an increase in permeability. The results also showed that the contaminated soils with a larger dosage of binders exhibited more significant deterioration during freeze-thaw cycles.

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Strength and Leaching Characteristics of Magnesium Phosphate Cement-Solidified Zinc- Contaminated Soil under the Effect of Acid Rain

Cited by 17 publications

References 20 publications

Influence of magnesium-to-phosphate ratio and water-to-cement ratio on hydration and properties of magnesium potassium phosphate cements

Influence of magnesium-to-phosphate ratio and water-to-cement ratio on hydration and properties of magnesium potassium phosphate cements

Designing Magnesium Phosphate Cement for Stabilization/Solidification of Zn-Rich Electroplating Sludge

Influence of Freeze–Thaw Cycles and Binder Dosage on the Engineering Properties of Compound Solidified/Stabilized Lead-Contaminated Soils

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