Remediation techniques for heavy metal-contaminated soils: Principles and applicability

Adsorption kinetic models: Physical meanings, applications, and solving methods.

Keywords: Mecanique des sols ; Drainage ; Ecoulement souterrain Reference Record created on 2004-09-07, modified on 2016-08-08

Applications of soil physics.

http://www.saetaequina.com/files/1-s2_0-S0950061811006763-main.pdf

A simple review of soil reinforcement by using natural and synthetic fibers

Removal of Methylene Blue from aqueous solutions by adsorption on Kaolin: Kinetic and equilibrium studies

The environmental challenges from coal mining include coal mine accidents, land subsidence, damage to the water environment, mining waste disposal and air pollution. These are either environmental pollution or landscape change. A conceptual framework for solving mine environmental issues is proposed. Clean processes, or remediation measures, are designed to address environmental pollution. Restoration measures are proposed to handle landscape change. The total methane drainage from 56 Chinese high methane concentration coal mines is about 101.94 million cubic meters. Of this methane, 19.32 million, 35.58 million and 6.97 million cubic meters are utilized for electricity generation, civil fuel supplies and other industrial purposes, respectively. About 39% of the methane is emitted into the atmosphere. The production of coal mining wastes can be decreased 10% by reuse of mining wastes as underground fills, or by using the waste as fuel for power plants or for raw material to make bricks or other infrastructure materials. The proper use of mined land must be decided in terms of local physical and socio-economical conditions. In European countries more than 50% of previously mined lands are reclaimed as forest or grass lands. However, in China more than 70% of the mined lands are reclaimed for agricultural purposes because the large population and a shortage of farmlands make this necessary. Reconstruction of rural communities or native residential improvement is one environmental problem arising from mining. We suggest two ways to reconstruct a farmer's house in China.

Environmental issues from coal mining and their solutions

The enormous amount of wastes produced during wood processing operations in many countries provides challenging opportunities for the use of wood waste as a construction material. In this research, wood waste (sawdust and wood shaving) ash (WWA) of pretreated timber of 0, 5, 10, 15, 20, 25, and 30% by weight of cement was added as a supplement to a concrete of mix proportion 1:2:4:0.56 (cement:sand:coarse aggregate:water cement ratio), and the strengths and the water absorption of the matrix were evaluated. Also, the metal leachability of WWA was analyzed. The compressive and the flexural strengths of WWA concrete for the ages investigated ranged from 12.83 to 28.66 N∕ mm2 , and 3.65 to 5.57 N∕ mm2 , respectively, with the lowest values obtained at 30% additive level of ash. When compared with the strength of plain concrete (control), the compressive and flexural strengths of WWA concrete were between 62 and 91% and 65 and 98%, respectively, of the former. The trend of the water absorption of WWA concrete...

Potential of Wood Waste Ash as an Additive in Concrete

In this paper, class F fly ash, bottom ash, polypropylene fibers, and nylon fibers were evaluated as potential stabilizers in enhancing volume change properties of sulfate rich expansive soils. As a part of the research evaluation, a comprehensive laboratory experimental program was designed and conducted on two different subgrade soils from two locations in Texas. Four dosage levels of each stabilizer, two compaction moisture content levels, and 14 days curing period were investigated. Volume change behavioral tests including volumetric free swell, volumetric shrinkage strain, and vertical swell pressure tests were conducted on both isolated stabilizer treated and combined ash-fiber stabilized soils. Ash stabilizers showed improvements in reducing swelling, shrinkage, and plasticity characteristics by 20–80% whereas fibers treatments resulted in varied improvements. In combined treatments, class F fly ash mixed with nylon fibers was the most effective treatment on both Dallas and Arlington soils, where the soil property enhancements were considered average-to-moderate. Possible mechanisms that resulted in the soil property improvements are discussed along with the recommended stabilizers and their dosages for expansive soil treatments.

Volume Change Behaviors of Expansive Soils Stabilized with Recycled Ashes and Fibers

Compression test results of kaolinite with water and nine organic fluids of a wide range of dielectric constants are presented in this paper. As the dielectric constant was increased from approximately 2 in nonpolar fluids to 80 in water, void ratio and compression index of the kaolinite decreased first, reaching a minimum at a dielectric constant of 24 in ethanol, and then increased. The swelling index also increased with the dielectric constant. The effects of the pore fluids are chiefly attributed to van der Waals attractive force. When the attractive force is large, shearing resistance at interparticle contacts is large, enabling soil particles to form an open-flocculated structure with large void ratio and compressibility. Efforts were made to accurately compute the attractive force for the kaolinite in the test fluids. Its variation with the dielectric constant agreed with the variation of compressibility qualitatively and compared with experimental results on stability of kaolinite/fluid suspensions reasonably well. Double-layer repulsive forces were also found to influence the compressibility slightly. Due to an increase in double-layer thickness, the compressibility increased with a decrease in electrolyte valence and concentration. The test results also indicate that the physiochemical effects diminish with an increase in overburden stress. Under an overburden stress of 300 kPa, pore fluid properties had essentially no effect on the compressibility of the kaolinite.

Pore Fluid Properties and Compressibility of Kaolinite

Desiccation cracking in drying soil is a common natural phenomenon, and it significantly impacts the soil’s mechanical and hydraulic behavior. In this study, experimental desiccation tests were conducted on an initially saturated soil layer. Several aspects of the behavior of the soil—water evaporation, volume shrinkage, crack initiation, and propagation—were investigated. By applying image processing techniques, the geometric or morphological characteristics of the crack patterns were quantitatively described. The results show that cracking occurred during the constant evaporation rate stage, when the soil was still fully saturated at a water content of 41%. A growing crack obeys certain objective laws, and it finally splits the soil surface into relatively regular patterns: The first crack generally occurs on surface defects at the bottom of “potholes” and at the fringe of aggregates. Cracks intersect with one another at right angles, and the final crack pattern is dominated by square shapes. Most crack...

Hilary I. Inyang

Papers

Environmental issues from coal mining and their solutions

Potential of Wood Waste Ash as an Additive in Concrete

Volume Change Behaviors of Expansive Soils Stabilized with Recycled Ashes and Fibers

Pore Fluid Properties and Compressibility of Kaolinite

Experimental Investigation of the Desiccation Cracking Behavior of Soil Layers during Drying