| Nondestructive testing and image analysis were used to evaluate various characteristics of geomembranes including thickness, surface characteristics, and underlying materials. Tests were conducted both in the laboratory and in the field. The thickness tests on smooth geomembranes were conducted on five types of geomembranes, including HDPE, PVC, PP, LLDPE, and EPDM. The thickness tests for textured geomembranes were conducted on 2 types of materials manufactured using 3 different textural motifs, including HDPE and LLDPE. The thicknesses on smooth geomembranes were determined using mechanical, ultrasonic, and magnetic methods. The thicknesses on textured geomembranes were determined using mechanical and image analysis methods. Comparisons were made between the thickness measurements obtained using different methods. Effectiveness of each method to determine the thicknesses accurately was investigated. The reasons for dissimilarities between thickness measurements were also investigated. Thickness distributions for the textured geomembranes were developed using image analysis method.; The surface characteristics of textured geomembranes were also determined. A technique was developed to categorize textured geomembranes based on surface properties. Optimum testing conditions for surface analysis were established.; Finally, use of nondestructive testing for determination of type and condition of materials underlying geomembranes was investigated. Ultrasonic pulse-echo technique was employed for investigation of the underlying materials. Differences between the amplitudes of the waveforms reflected from bottom of the geomembranes were determined and used for identifying the type and condition of the underlying materials.; Overall, it is determined that nondestructive testing and image analysis can be used to characterize properties of geomembranes. These methods offer various advantages over conventional destructive methods including ease of use, applicability in the field, and more representative measurements. |
