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The construction of man-made barriers in the ground is one of the traditional tasks of civil engineers. During the last few years this activity has become increasingly important particularly with regard to protecting the environment from hazardous wastes. One method for the securing of old waste deposits is their encapsulation with vertical barriers, using plastic-concrete cut-off walls.
In this paper, the securing of a hazardous waste deposit in Switzerland with such a vertical barrier is described. The suitability of different materials for the cut-off walls was investigated. Mineral sealing materials of different compounds were used. The workability of new concrete mixtures was tested, and their mechanical, chemical and mineralogical properties examined in the laboratory. Of great importance was the influence of the contamined ground water on the barrier material itself. The long-term concrete behaviour due to chemical attack was investigated using a number of different testing methods. The determination of permeability, diffusion, retention and pore-radius were the principal areas of interest.
The influence of various thinner liquids on the workability of the new mixtures was investigated, and the hardening properties of these mixtures tested.
The construction of a full scale test cut-off wall (at a scale 1:1 on a building site) allowed an evaluation to be made of the field behaviour of these plastic-concrete wall materials. The results gave indications regarding workability, hardening, cracking and joints. A comparison was possible between the test results obtained in the laboratory, and those from the full scale field investigation.
Finally, some general advice is given which will be usefull when isolating hazardous waste deposits using vertical barrier systems of plastic-concrete rnaterial.
Clay; ClayGroup; remediation; encapsulation; slurry walls; contaminated sites; barriers; Ton; Einkapselung; Dichtwande; Barrieren; Altlasten; Sickerung; Sanierung