THE FEASIBILITY OF MUDSTONE MATERIAL AS A NATURAL LANDFILL LINER

This paper presents the results of a series of laboratory tests invest igating on physical properties and hydraulic conductive behaviors of a mudstone material obtained from southwestern Taiwan. The Atterberg li mits and particle-size distribution examinations showed the liquid lim it = 34.1%, the plasticity index = 15.2%, the percentage fines (< No. 200 sieve) greater than or equal to 95.1%, the percentage of clay (< 2 mu m) greater than or equal to 30%, and the activity = 0.5. These cha racteristics perfectly satisfied the essential requirements for soil p roperties of landfill liner. Based on the column experiments using two different grain sizes of beads to simulate the mudstone liner constru cted on the gravel and the sandy soil, the hydraulic conductivity less than or equal to 1 x 10(-7) cm/s could be achieved if the hydraulic g radient is less than 13.9 (gravel) and 17.8 (sand), respectively. Howe ver, the hydraulic conductivity rose with an increase in hydraulic gra dient. It was attributed to the fine granular mudstone penetrated thro ugh the simulated beads and led to the fine granular mudstone that cou ld not fill up the void of beads. Moreover, the results of permeabilit y tests performed using the rigid-wall and flexible-wall permeameters revealed that all of the hydraulic conductivities were less than 1 x 1 0(-7) cm/s for the mudstone with water contents from 17% to 37% (rigid -wall) and 14% to 29% (flexible-wall). Thus, it was confidently expect ed that this mudstone material could be applied on landfill soil liner . (C) 1998 Elsevier Science B.V.