Long-term leaching behaviours of cement composites prepared by hazardous wastes

Yang, Zhenzhou; Ji, Ren; Liu, Huan; Wang, Xidong; Zhang, Zuotai

doi:10.1039/c8ra02773k

Cited by 6 publications

(1 citation statement)

References 35 publications

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“…Whilst this study has demonstrated that the STSB-GGBS binder has very good geoenvironmental credentials in terms of leaching performance, small-scale modification to the binder design and/or dosage is required to further reduce the mobility of Pb and longerterm leaching testing is recommended. According to the NEN 7375 protocol, concretes should be subjected to regular leachate testing over 180-days, as undertaken by Yang et al (2018) who assessed an eco-friendly Portland cement-based concrete containing sewage treatment sludge as a partial replacement for CEM-I. Finally, an environmental impact analysis of the STSB-GGBS binder is recommended for future work, involving the use of life cycle analysis frameworks with cradle-to-cradle approaches.…”

Section: Conclusion and Recommendationsmentioning

confidence: 99%

Compressibility, Structure, and Leaching Assessments of an Alluvium Stabilized with a Biochar–Slag Binder

Sargent,

Gonzalez,

Ennis

2023

J. Geotech. Geoenviron. Eng.

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Deep dry soil mixing is a ground improvement technique commonly used for treating soft soils. Portland cement is the most commonly used binder, but its long-term use is unsustainable due to the high CO2 emissions associated with its manufacture. Alkali-activated cements are a low carbon alternative, involving the use of pozzolanic industrial by-products and wastes. This study provides insights into the one-dimensional compressibility, internal cemented 'structure' and leaching characteristics of an alluvial soil stabilised with a new 100% waste-based cementitious binder, comprising biochar as the alkali activator and blast furnace slag as the pozzolan. The binder has recently been demonstrated by the authors to satisfy European soil stabilisation 28-day compressive strength requirements when using dosages of 7.5 and 10% by dry weight. The biochar successfully activated the pozzolanic properties of the slag; whereby the stabilised soil mixtures developed a cemented microstructure which resulted in improvements in compressibility and stiffness. Oedometer datasets for untreated, biocharslag-and CEM-II-stabilised alluvium were successfully processed through a framework developed by the authors to quantify their artificially cemented internal structure, for use as an input parameter in advanced constitutive soil models. Leaching results indicated that the heavy and trace metal content of 1-and 28-day cured biochar-slag stabilised samples complied with UK and European waste acceptance criteria, and mean baseline heavy metal concentrations for groundwater resources in England and Wales. This study advocates the new biochar-slag binder as a suitable replacement for Portland cements in soil stabilisation, contributing to the path towards net zero carbon emissions for the ground engineering sector and improving the circular economy.

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Section: Conclusion and Recommendationsmentioning

confidence: 99%

Compressibility, Structure, and Leaching Assessments of an Alluvium Stabilized with a Biochar–Slag Binder

Sargent,

Gonzalez,

Ennis

2023

J. Geotech. Geoenviron. Eng.

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Immobilization of radioactive sulphate waste simulate in polymer–cement composite based on recycled expanded polystyrene foam: evaluation of the final waste form resistance for Cs-134 and Co-60 leachability

Eskander,

Bayoumi,

Tawfik

2024

J Radioanal Nucl Chem

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The present study investigates to incorporate spiked sulfate solution simulate into polymer–cement composite (PCC) based on recycled expanded polystyrene foam. The main aim is to convert the waste stream into leach resistance solid forms able to slow down or even to retard the back release of hazardous radionuclides to the surrounding. Effective parameters e.g. leachant medium, temperature, radioactivity contents, leachant volumes and radionuclides speciation versus the leaching time were studied. The incremental leach rate (Rn, cm/day) and the leach index (Lx) were evaluated for the final waste form after 145 days. The experimental results revealed that the Lx for the all variances can fulfil the waste acceptance criteria for the disposal facility and are above the threshold value of 6. Moreover, leach rate percentages for Cs-134 and Co-60 were not exceeding 2%. The acquired data, based on lab leaching experiments, can recommend the developed PCC under consideration for solidification of radioactive sulphate waste stream safely.

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Valorization of incinerator bottom ash for the production of resource-efficient eco-friendly concrete: Performance and toxicological characterization

Ramesh¹,

Vongole²,

Nagraj³

et al. 2021

Archit. Struct. Constr.

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In recent times, the quantity of wastes generated from industries, hospitals, construction sites etc. is perpetually increasing from year to year. Producing concrete utilizing waste or discarded materials as a partial replacement to fine or coarse aggregates is one among the effective ways of waste utilization. The disposal of incinerator bottom ash usually produced by the incineration of inorganic constituents of the municipal solid wastes (MSW) in an eco-friendly way is one of the issues of concern, globally. By the way, the present study is related to the utilization of MSW incinerator bottom ash and recycled demolition waste aggregate as partial replacement materials for fine and coarse aggregate, respectively to produce eco-friendly concrete. This study adopted an innovative pretreatment technique for stabilizing the MSW incinerator bottom ash. Five distinct M20 grade concrete mixes were produced with different proportions of fine aggregate, MSW incinerator bottom ash, coarse aggregate, and recycled demolition waste aggregate along with cement and water. The incinerator bottom ash was replaced at 5% and 10% quantities with fine aggregate and the recycled demolition waste aggregate was replaced at 40% and 60% of the weight of the coarse aggregate. The strength and durability properties of the M20 grade concrete were analyzed. It was noticed that the strength and durability properties of the eco-friendly concrete specimens produced by incorporating 5% -incinerator bottom ash and 40% -recycled demolition waste aggregate were superior to that of the control mix concrete. Laboratory tank leaching tests showed that the eco-friendly concrete do not pose any significant environmental hazard. Furthermore, the microstructural analysis through scanning electron microscope (SEM) images, revealed dense aggregate paste matrix interfaces with less micro-pores and insignificant micro-cracks due to the incorporation of incinerator bottom ash as a partial replacement to the fine aggregate.

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Long-term leaching behaviours of cement composites prepared by hazardous wastes

Abstract: In order to evaluate the long-term environmental impact of Eco-Ordinary Portland Cement (EOPC) prepared by hazardous wastes, long-term leaching tests were conducted on the EOPC composites under deionized and saline water conditions.

Cited by 6 publications

References 35 publications

Compressibility, Structure, and Leaching Assessments of an Alluvium Stabilized with a Biochar–Slag Binder

Compressibility, Structure, and Leaching Assessments of an Alluvium Stabilized with a Biochar–Slag Binder

Immobilization of radioactive sulphate waste simulate in polymer–cement composite based on recycled expanded polystyrene foam: evaluation of the final waste form resistance for Cs-134 and Co-60 leachability

Valorization of incinerator bottom ash for the production of resource-efficient eco-friendly concrete: Performance and toxicological characterization

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