Measurements of the Permeability Coefficient of Waste Coal Ash under Hydrostatic Pressure to Identify the Feasibility of Its Use in Construction

Abstract

The aim of this research was to measure the filtration properties of waste coal ash under the influence of hydrostatic pressure generated in a three-axial compression apparatus. The scope of work included determining the compactibility parameters, maximum bulk density and optimal moisture content. Permeability tests were performed for a sample with an average grain composition at three compaction indices IS: 0.964, 0.98 and 1.00. The hydrostatic pressure ranging from 0.5 to 1.8 bar corresponded to the layer depths from 2.17 to 7.83 m. Gradually increasing the pressure during the first loading cycle caused irreversible changes in the structure of the sample by local material agglomeration or grain interlocking. The water permeability coefficient was higher in the second loading cycle than in the first cycle. It was shown that waste coal ash cannot be used as a construction material on its own. To obtain constant filtration properties, the waste coal ash material should be doped, or an optimal compactionshould be used (IS = 1.00). The results presented in this study are important for assessing the use of waste coal ash for construction engineering purposes.