Shrinkage characteristics of heat-tacked GCL seams

The behavior of heat-tacked GCL seams under cyclic wetting and drying is examined. It is shown that the transverse shrinkage behavior of heat-tacked seams was similar to that observed in previous shrinkage tests performed on unseamed GCL. It is shown that the heat-tacked seam has strength comparable to the GCL adjacent to the seam and hence it is likely the strength of the GCL itself that will govern failure of the GCL in applications where there can be significant shrinkage. The strength of the heat-tacked seam subjected to 40 wet-dry cycles was at least as high as that of virgin heat-tacked samples, suggesting that 40 wet-dry cycles did not weaken the heat-tacked seam. After 40 cycles, the samples remained heat-tacked, suggesting the technique has promise as one method of preventing panel shrinkage for GCLs highly susceptible to shrinkage. It is noted that these tests are small-scale laboratory tests, under idealized conditions, and that the behavior in the field may differ due to more extreme conditions that may occur in the field and due to the greater amount of material between seams available to shrink and hence induce forces in the heat-tacked GCL seam.