Permeability and Consolidation Characteristics of Compacted Fly Ash

Abstract

Detailed testing regarding geotechnical utilization was carried out on fly ash from the Dadri thermal power station. The chemical composition and physical properties of the fly ash were determined. The morphology of the fly ash particles was studied by scanning electron microscopy. An X-ray diffraction test was also conducted. The geotechnical testing program included the classification tests, the compaction test, the consolidation test, and the permeability test. The influence of the head loss across the specimen, the effective stress, and the void ratio on the permeability was studied. The paper explains the details and results of the tests, especially those of the consolidation and permeability behaviors. The results showed that the coefficients of permeability and consolidation of the compacted fly ash were comparable to those of nonplastic silts. The variation in head loss across the specimen had only a small influence on the coefficient of permeability. Even at a high effective stress there was no appreciable reduction in the coefficient of permeability. The consolidation and permeability characteristics of the Dadri fly ash have been compared with those of some other Indian fly ashes. The geotechnical utilization of the Dadri fly ash has been explained through illustrative examples.