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Chao Yan - One of the best experts on this subject based on the ideXlab platform.
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Expansive soil modified by waste steel slag and its application in Subbase Layer of highways
Soils and Foundations, 2019Co-Authors: Qianwen Liu, Yongfeng Deng, Qi Feng, Chao YanAbstract:Abstract Steel slag is a waste by-product of the steel industry. The recycling usage of steel slag is limited due to the mutative chemical compositions it contains and its low cementation. In this investigation, the composition adjustment and activation of steel slag were studied to produce an optimal slag-based composite with improved cementation efficiency. The controlling moduli of cement clinker were introduced to standardise the composite. Subsequently, the composite was used to modify Hefei expansive soil (a kind of engineering waste for swelling properties) in embankment construction. The basic physical properties including free swelling ratio, California bearing ratio, unconfined compressive strength, microstructure, and mineral evolution were evaluated to understand the engineering performance and mechanism of modified expansive soils. The results show that the cementation of the slag was significantly improved after the composition adjustment and activation. Furthermore, the treated soil can satisfy the requirement of the Chinese standard for first-class road/highway when the composite incorporation ratio is more than 5%. The microstructural and mineralogical analysis shows that the component adjustment and activation enrich the cementation of the slag, resulting in the suppression of the swelling potential and improved strength. The above findings improve the reuse efficiency of steel slag, especially in expansive soil modifications.
Thomas Hojlund Christense - One of the best experts on this subject based on the ideXlab platform.
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life cycle assessment of disposal of residues from municipal solid waste incineration recycling of bottom ash in road construction or landfilling in denmark evaluated in the road res model
Waste Management, 2007Co-Authors: Harpa Irgisdotti, Gurbakhash Singh Hande, Michael Zwicky Hauschild, Thomas Hojlund ChristenseAbstract:Two disposal methods for MSWI bottom ash were assessed in a new life cycle assessment (LCA) model for road construction and disposal of residues. The two scenarios evaluated in the model were: (i) landfilling of bottom ash in a coastal landfill in Denmark and (ii) recycling of bottom ash as Subbase Layer in an asphalted secondary road. The LCA included resource and energy consumption, and emissions associated with upgrading of bottom ash, transport, landfilling processes, incorporation of bottom ash in road, substitution of natural gravel as road construction material and leaching of heavy metals and salts from bottom ash in road as well as in landfill. Environmental impacts associated with emissions to air, fresh surface water, marine surface water, groundwater and soil were aggregated into 12 environmental impact categories: Global Warming, Photochemical Ozone Formation, Nutrient Enrichment, Acidification, Stratospheric Ozone Depletion, Human Toxicity via air/water/soil, Ecotoxicity in water/soil, and a new impact category, Stored Ecotoxicity to water/soil that accounts for the presence of heavy metals and very persistent organic compounds that in the long-term might leach. Leaching of heavy metals and salts from bottom ash was estimated from a series of laboratory leaching tests. For both scenarios, Ecotoxicity(water) was, when evaluated for the first 100 yr, the most important among the twelve impact categories involved in the assessment. Human Toxicity(soil) was also important, especially for the Road scenario. When the long-term leaching of heavy metals from bottom ash was evaluated, based on the total content of heavy metals in bottom ash, all impact categories became negligible compared to the potential Stored Ecotoxicity, which was two orders of magnitudes greater than Ecotoxicity(water). Copper was the constituent that gave the strongest contributions to the ecotoxicities. The most important resources consumed were clay as liner in landfill and the groundwater resource which was potentially spoiled due to leaching of salts from bottom ash in road. The difference in environmental impacts between landfilling and utilization of bottom ash in road was marginal when these alternatives were assessed in a life cycle perspective.
Qianwen Liu - One of the best experts on this subject based on the ideXlab platform.
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Expansive soil modified by waste steel slag and its application in Subbase Layer of highways
Soils and Foundations, 2019Co-Authors: Qianwen Liu, Yongfeng Deng, Qi Feng, Chao YanAbstract:Abstract Steel slag is a waste by-product of the steel industry. The recycling usage of steel slag is limited due to the mutative chemical compositions it contains and its low cementation. In this investigation, the composition adjustment and activation of steel slag were studied to produce an optimal slag-based composite with improved cementation efficiency. The controlling moduli of cement clinker were introduced to standardise the composite. Subsequently, the composite was used to modify Hefei expansive soil (a kind of engineering waste for swelling properties) in embankment construction. The basic physical properties including free swelling ratio, California bearing ratio, unconfined compressive strength, microstructure, and mineral evolution were evaluated to understand the engineering performance and mechanism of modified expansive soils. The results show that the cementation of the slag was significantly improved after the composition adjustment and activation. Furthermore, the treated soil can satisfy the requirement of the Chinese standard for first-class road/highway when the composite incorporation ratio is more than 5%. The microstructural and mineralogical analysis shows that the component adjustment and activation enrich the cementation of the slag, resulting in the suppression of the swelling potential and improved strength. The above findings improve the reuse efficiency of steel slag, especially in expansive soil modifications.
Ivan Drouadaine - One of the best experts on this subject based on the ideXlab platform.
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Ten-year chemical evolution of leachate and municipal solid waste incineration bottom ash used in a test road site
Journal of Hazardous Materials, 2009Co-Authors: David Dabo, Rabia Badreddine, Laurent De Windt, Ivan DrouadaineAbstract:The use of municipal solid waste incineration (MSWI) bottom ash for road and car-park construction is an appropriate solution to reduce their disposal and the consumption of natural materials. In addition to leaching tests, the environmental impact assessment of such a waste recycling scenario critically needs for reliable long-term field data. This paper addresses a 10-year pilot site where MSWI bottom ashes have been used as road aggregates in Northern France (oceanic temperate climate). The paper focuses on the long-term evolution of leachate chemistry and the mineralogical transformations of MSWI bottom ash over 10 years. Data interpretation is supported by geochemical modeling in terms of main pH-buffering processes. The leachate pH and concentrations in major elements (Ca, Na and Cl) as well as in Al and heavy metals (Cu, Pb and Zn) quickly drop during the first 2 years to asymptotically reach a set of minimum values over 10 years; similar to those of a reference road built with natural calcareous aggregates. SO4 release makes exception with a slightly increasing trend over time. Carbonation induced by CO2 inputs, which leads to the successive dissolution of portlandite, CSH and ettringite, is one of the main phenomenon responsible for the geochemical evolution of leachate. On the other hand, mineralogical observations and batch tests demonstrate a relative stability of the MSWI bottom ash inside the Subbase Layer. In particular, carbonation may be far to be completed and still in progress after 10 years. This is consistent with preferential rainwater flow and dilution at the road edges combined to diffusion inside the Subbase Layer.
R.c. Graves - One of the best experts on this subject based on the ideXlab platform.
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Performance of experimental highway base and Subbase Layers containing by-product materials from a coal-fired power plant: KY Route 3074, Bleich Road. Interim research report
1993Co-Authors: D.q. Hunsucker, R.c. GravesAbstract:Three 750-foot test sections of a 22-foot wide roadway were constructed on newly constructed subgrade in May and June, 1988. The three experimental sections contained experimental base and Subbase Layers comprised of mixtures utilizing by-product materials from a coal-fired power plant. One test section included a base Layer containing residue from an atmospheric fluidized bed combustion (AFBC) process, size No. 57 aggregate, and Class F fly ash. The second test section included a base Layer constructed ponded fly ash, hydrated lime, and dense-graded aggregate. The third test section included a Subbase Layer constructed of pond ash stabilized with AFBC residue. A control section was included in the study for comparison purposes. Previous reports have documented preliminary engineering, construction details, and initial performance evaluations of the three experimental sections constructed on State Route 3074 in McCracken County, Kentucky. This report summarizes performance information derived from the field trials. Performance measurements included distress surveys, Road Rater deflections, pavement rutting measurements, and field cores of the experimental base and Subbase Layers were obtained for laboratory evaluations. The two test sections containing residue from the AFBC process were regarded as failures due to the excessive expansion of the materials, although efforts were made tomore » eliminate, or minimize, the inherent expansive properties of the residue by prehydrating the AFBC residue prior to its use in the mixtures. The two Layers were eventually removed and replaced with conventional materials. The remaining experimental section has given good performance and service. No significant distresses have been noted. Rutting measurements indicated less rutting occurring in the ponded fly ash-hydrated lime-dense grade aggregate section than in the control section. Analyses of deflection data indicate superior structural characteristics.« less
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Performance of experimental highway base and Subbase Layers containing coal-fired power plant by-product materials: KY Route 3074, Bleich Road
1993Co-Authors: D.q. Hunsucker, R.c. GravesAbstract:Three 750-ft (26-m) test sections of a 22-ft (6.7-m) wide roadway were constructed on newly constructed subgrade in May and June, 1988. The three experimental sections contained experimental base and Subbase Layers comprised of mixtures utilizing by-product materials from a coal-fired power plant. One test section included a base Layer containing residue from an atmospheric fluidized bed combustion (AFBC) process, size No. 57 aggregate, and Class F fly ash. The second test section included a base Layer constructed of ponded fly ash, hydrated lime, and dense-graded aggregate. The third test section included a Subbase Layer constructed of pond ash stabilized with AFBC residue. A control section was included in the study for comparison purposes. Previous reports have documented preliminary engineering, construction details, and initial performance evaluations of the three experimental sections constructed on State Route 3074 in McCracken County, Kentucky. This report summarizes performance information derived from the field trials. Performance measurements included distress surveys, Road Rater deflections, pavement rutting measurements, and strength and durability measurements of field cores obtained from the experimental base and Subbase Layers for laboratory evaluations. The two test sections containing residue from the AFBC process were regarded as failures due to the excessive expansion of the materials, although efforts were made to eliminate, or minimize, the inherent expansive properties of the residue by prehydrating the AFBC residue prior to its use in the mixtures. The two Layers were eventually removed and replaced with conventional materials. The remaining experimental section has given good performance and service. No significant distresses have been noted. Rutting measurements indicated less rutting occurring in the ponded fly ash-hydrated lime-dense graded aggregate section than in the control section. Analyses of deflection data indicate superior structural characteristics compared to the control section. Unconfined compression tests indicate excellent strengths of the experimental mixture. The accomplishment of this application confirms that waste fly ash may be used successfully in stabilized road base construction.
