Hydraulic conductivity of fly ash as a barrier material: some problems in determination
Katarzyna Zabielska-Adamska
Abstract
Abstract Recently, researchers have conducted investigations with the possibility of utilising fly ash as a barrier material, which is justified by its chemical, physical and mechanical properties. The mean necessary characteristic, which should be tested is coefficient of permeability. The diversification of test methods and sample preparation techniques can significantly change test results. The purpose of the article is to describe the fly ash permeability in dependence on compaction and moisture content at compaction, as a material embedded into the sealing layer of storage yards. The impact of sample saturation on hydraulic conductivity is shown too. The hydraulic conductivity was investigated for unsaturated and fully saturated fly ash samples, which had been compacted by the Standard and Modified Proctor methods at various water contents, ranging over optimum water content ± 5%. The lowest values of hydraulic conductivity were obtained at the highest moisture contents w = w opt + 5%, for both compaction methods. It is proven that compacted fly ash, in spite of its likeness to non-cohesive soils, must be assessed while considering water content during compaction, as in the case of compacted cohesive soils.