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Backfill Material
The Experts below are selected from a list of 6264 Experts worldwide ranked by ideXlab platform
Henghu Sun – One of the best experts on this subject based on the ideXlab platform.
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Performance and leaching analysis of a novel coal sludge-based Backfill Material
Clean Technologies and Environmental Policy, 2012Co-Authors: Yuan Yao, Henghu Sun, Shushu Jiang, Rui Zhang, Chao Feng, Xiaoyuan HanAbstract:In this article, an innovative Backfill Material is introduced as a green Material largely utilizing two major coal mining waste: coal refuse and coal sludge. Coal refuse is rock-like solid waste, comparatively, raw coal sludge is slurry. A smart recipe design of Backfill Material was introduced, which contains only 1 % of cement and the rest 99 % of raw Material is from industry waste. The Backfill Material at 75 % pulp density shows excellent performance such as high unconfined compressive strength, great flowability, and low bleeding rate. Also, the article discusses the morphology change of the Backfill harden body during different curing ages, the observation through SEM–EDS illustrates the distinguished morphological characterization of the needle-like ettringite and amorphous gel. Furthermore, TCLP results indicate that this designed Backfill Material is environmentally acceptable and none of the heavy metal leaching has over the limitation by US Environmental Protection Agency (EPA).
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Characterization of a new silica alumina-based Backfill Material utilizing large quantities of coal combustion byproducts
Fuel, 2012Co-Authors: Yuan Yao, Henghu SunAbstract:Abstract In this paper, a new silica alumina-based Backfill Material utilizing large quantities of coal combustion byproducts (CCPs) was investigated. The experimental results show that this Material had excellent workability as fresh Backfill slurry because of its high flowability and low bleeding rate, and the data also demonstrate that the Material had good mechanical properties in a compressive test, as the hardening body of the Backfill Material reached around 7 MPa in 360 days. The results indicate that milled fly ash with a large specific surface area (represented as the Blaine value) significantly enhanced the performance of the silica alumina-based Backfill Material. The optimal design for this Backfill Material in this experiment was a composition of 30% milled fly ash at a pulp density 75.2%. Although the Backfill slurry contained a large amount of industrial solid waste, the TCLP results indicate that none of the tested hazardous elements exceeded EPA limits, indicating that this Backfill Material is able to stabilize and/or solidify the hazardous elements very well.
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a novel silica alumina based Backfill Material composed of coal refuse and fly ash
Journal of Hazardous Materials, 2012Co-Authors: Yuan Yao, Henghu SunAbstract:Abstract In this paper, a systematic study was conducted to investigate a novel silica alumina-based Backfill Material composed of coal refuse and fly ash. The coal refuse and fly ash had different properties under various thermal activation temperatures (20 °C, 150 °C, 350 °C, 550 °C, 750 °C and 950 °C). It is known that a thermal activation temperature ranging from 20 °C to 950 °C significantly increases the flowability and pozzolanic properties of the coal refuse; however, the flowability of fly ash decreases when the activation temperature is higher than 550 °C because of a severe agglomeration phenomenon on its surface. An optimal design for this Backfill Material was determined to include an activated portion composed of 5% coal refuse at 750 °C and 15% fly ash at 20 °C. This combination yields the best performance with excellent flowability, a high compressive strength and a low bleeding rate. The microanalysis results corresponded well with the performance tests at different activation conditions. In the coal refuse, kaolinite peaks began to decrease because of their transformation into metakaolin at 550 °C. Chlorite peaks disappeared at 750 °C. Muscovite peaks decreased at 750 °C and disappeared at 950 °C. During this process, muscovite 2M 1 gradually dehydroxylated to muscovite HT. Furthermore, this paper examined the environmental acceptance and economic feasibility of this technology and found that this silica alumina-based Backfill Material composed of coal refuse and fly ash not only meets EPA requirements but also has several advantages in industry feasibility when compared with hydraulic Backfill, rock Backfill and paste Backfill.
Yuan Yao – One of the best experts on this subject based on the ideXlab platform.
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Performance and leaching analysis of a novel coal sludge-based Backfill Material
Clean Technologies and Environmental Policy, 2012Co-Authors: Yuan Yao, Henghu Sun, Shushu Jiang, Rui Zhang, Chao Feng, Xiaoyuan HanAbstract:In this article, an innovative Backfill Material is introduced as a green Material largely utilizing two major coal mining waste: coal refuse and coal sludge. Coal refuse is rock-like solid waste, comparatively, raw coal sludge is slurry. A smart recipe design of Backfill Material was introduced, which contains only 1 % of cement and the rest 99 % of raw Material is from industry waste. The Backfill Material at 75 % pulp density shows excellent performance such as high unconfined compressive strength, great flowability, and low bleeding rate. Also, the article discusses the morphology change of the Backfill harden body during different curing ages, the observation through SEM–EDS illustrates the distinguished morphological characterization of the needle-like ettringite and amorphous gel. Furthermore, TCLP results indicate that this designed Backfill Material is environmentally acceptable and none of the heavy metal leaching has over the limitation by US Environmental Protection Agency (EPA).
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Characterization of a new silica alumina-based Backfill Material utilizing large quantities of coal combustion byproducts
Fuel, 2012Co-Authors: Yuan Yao, Henghu SunAbstract:Abstract In this paper, a new silica alumina-based Backfill Material utilizing large quantities of coal combustion byproducts (CCPs) was investigated. The experimental results show that this Material had excellent workability as fresh Backfill slurry because of its high flowability and low bleeding rate, and the data also demonstrate that the Material had good mechanical properties in a compressive test, as the hardening body of the Backfill Material reached around 7 MPa in 360 days. The results indicate that milled fly ash with a large specific surface area (represented as the Blaine value) significantly enhanced the performance of the silica alumina-based Backfill Material. The optimal design for this Backfill Material in this experiment was a composition of 30% milled fly ash at a pulp density 75.2%. Although the Backfill slurry contained a large amount of industrial solid waste, the TCLP results indicate that none of the tested hazardous elements exceeded EPA limits, indicating that this Backfill Material is able to stabilize and/or solidify the hazardous elements very well.
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a novel silica alumina based Backfill Material composed of coal refuse and fly ash
Journal of Hazardous Materials, 2012Co-Authors: Yuan Yao, Henghu SunAbstract:Abstract In this paper, a systematic study was conducted to investigate a novel silica alumina-based Backfill Material composed of coal refuse and fly ash. The coal refuse and fly ash had different properties under various thermal activation temperatures (20 °C, 150 °C, 350 °C, 550 °C, 750 °C and 950 °C). It is known that a thermal activation temperature ranging from 20 °C to 950 °C significantly increases the flowability and pozzolanic properties of the coal refuse; however, the flowability of fly ash decreases when the activation temperature is higher than 550 °C because of a severe agglomeration phenomenon on its surface. An optimal design for this Backfill Material was determined to include an activated portion composed of 5% coal refuse at 750 °C and 15% fly ash at 20 °C. This combination yields the best performance with excellent flowability, a high compressive strength and a low bleeding rate. The microanalysis results corresponded well with the performance tests at different activation conditions. In the coal refuse, kaolinite peaks began to decrease because of their transformation into metakaolin at 550 °C. Chlorite peaks disappeared at 750 °C. Muscovite peaks decreased at 750 °C and disappeared at 950 °C. During this process, muscovite 2M 1 gradually dehydroxylated to muscovite HT. Furthermore, this paper examined the environmental acceptance and economic feasibility of this technology and found that this silica alumina-based Backfill Material composed of coal refuse and fly ash not only meets EPA requirements but also has several advantages in industry feasibility when compared with hydraulic Backfill, rock Backfill and paste Backfill.
Andrea Vallati – One of the best experts on this subject based on the ideXlab platform.
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The performance analysis of a new thermal Backfill Material for underground power cable system
Applied Thermal Engineering, 2016Co-Authors: Paweł Ocłoń, Marco Bittelli, Paul Cisek, Eva Kroener, Marcin Pilarczyk, Dawid Taler, Ravipudi Venkata Rao, Andrea VallatiAbstract:Lafarge Gruntar™ Material is proposed in this paper as a new thermal Backfill component, and different mass fractions such as 5%, 10%, and 15% are examined. The thermal properties of the developed Backfill are determined by experiments with respect to water content and time. Based on the experimental data it is found that the 15% mass fraction Lafarge Gruntar™ Material provides the most favorable thermal conductivity i.e. over 1.00 W/(m K) in the dry state. This paper also presents a thermal performance optimization procedure for the high voltage underground power cable system. The new thermal Backfill Material is considered to be installed within the cable system to improve its thermal performance. The analyzed system consists of three underground power cables situated in a flat formation (in−line arrangement) in thermal Backfill, buried in the native soil. To avoid extensive mechanical loads caused by vibrations, when locating beneath a paved ground (e.g. under road crossings), the cables are situated in High Density Polyethylene (HDPE) casing pipes filled with sand−bentonite mixture. The pipes are then placed into a thermal Backfill and buried in the native soil. The Installation of thermal Backfill Material is relatively expensive since in many cases the buried line is installed over many kilometers. Therefore, it is important to determine the optimal dimensions of the cable bedding layer to minimize the Material and installation costs while keeping efficient heat dissipation from the cables. The momentum-type Particle Swarm Optimization (PSO) solver, with a dynamic penalty function, is used to minimize the cable Backfill cross-sectional area while not exceeding the allowable temperature of the cable operation. The performed optimization procedure obtains the converged solution. The temperature distribution in soil, cables, and the cable Backfill layer is determined using the Finite Element Method. The Campbell − de Vries thermal conductivity model is employed for the soil surrounding the underground power cable system. An MATLAB code is written for solving the heat conduction equation and to determine the temperature distribution within the underground power cable system. By using the momentum-type Particle Swarm Optimization algorithm, it is possible to design the best-found dimensions of the cable bedding layer (width and height). Moreover, the dynamic penalty function employed in the optimization procedure has assured the determination of the maximum temperature of cable conductor close to its best-found value.