Feasibility study on the application of coal gangue as landfill liner material.

In the present study, influence of wetting–drying cycles on swelling pressures of sand–bentonite mixtures used in the construction of sanitary landfills to have an impermeable liner was investigated before and after lime treatment of the mixtures. Swelling pressure tests were conducted to see if the swelling pressures were affected by wetting–drying cycles. First series of specimens were prepared as a mixture of sand and bentonite only. In the first series of specimens, sand was mixed with bentonite in various proportions with their optimum water contents and compacted by using standard proctor energy. In the second series of the specimens, lime in various proportions was added to the mixtures of sand–bentonite. Then, the sand–bentonite mixtures stabilized by lime were compacted with the standard proctor energy at their optimum moisture contents. Five wetting–drying cycles were performed on each specimen and values of swelling pressures were measured at the end of each cycle. Results of swelling pressure tests indicated that the swelling pressure is decreased when lime is added to the mixtures. In addition, decrements were observed on swelling pressures by wetting–drying cycles. The results of the experiments of this investigation showed that the beneficial effect of lime stabilization to control the swelling pressures was partly lost by the wetting–drying cycles. However, the test results indicated that the swelling pressures of the specimens made of sand–bentonite mixtures stabilized by lime were lower than the swelling pressures of the specimens made of only sand–bentonite mixtures.

Effect of wetting-drying cycles on swelling behavior of lime stabilized sand-bentonite mixtures

Quantity-based and toxicity-based evaluation of the U.S. Toxics Release Inventory.

This paper presents the consolidation and swelling characteristics of fly ash–montmorillonite clay mixes. Nine types of fly ash samples collected from different thermal power plants of the Eastern part of India have been used in this study. The amount of montmorillonite clay added to each fly ash sample is 10, 20, 30, 40, and 50%. The compression index (cc) of the fly ashes indicates that the rate of consolidation is very fast. With an increase in montmorillonite clay content from 0.0 to 50%, the compressibility of the fly ash–montmorillonite clay mix increases, irrespective of the type of fly ash. The value of the compression index (cc) of montmorillonite clay indicates that the embankments and fills made of fly ash–montmorillonite clay mixtures (i.e., 30, 40, and 50% of montmorillonite clay in the mix) and the structures constructed on such fills would suffer large deformation, whereas fly ash and fly ash mixed with 20% montmorillonite clay would not suffer large deformation. Specimens used for ...

Volume Change Behavior of Fly Ash–Montmorillonite Clay Mixtures

Laboratory and field testing for utilization of an excavated soil as landfill liner material.

A series of permeameters (columns) was used to evaluate the effects of the percolation of water and 1,000 {micro}g/mL of zinc chloride solution through a mixture of montmorillonite clay, sand, and lime. The column test results show that the addition of lime changes the chemical and physical properties of the clay. The hydraulic conductivities for the mixture of clay with different percentages of lime at first increases with increasing lime and then decreases with increasing lime. The breakthrough curves indicate that the Zn(II) capture is increased and Zn(II) breakthrough is delayed with increasing lime addition. Lime also enhances the clay/lime mixture`s ability to resist puncture by sharp objects. Based on the effects of lime on Zn(II) captured by the clay, an explanation for the interacting effects of lime and Zn(II) capture on changing hydraulic conductivity is suggested. The results of this research demonstrate the potential of using lime-treated clay liners for landfills. Such liners would have lower hydraulic conductivity, better resistance to puncture, and enhanced ability to capture heavy metals.

T.D. Tsai

Papers

A new landfill liner to reduce ground-water contamination from heavy metals