Development of a nondestructive test method for seams of polymeric waterproofing membranes (feasibility study) (FGU2004/003)
Overview
Background & policy context:
In practice, the existing test methods for welded seams of polymeric waterproofing membranes appear to be costly and of limited value. Several arguments seem to favor the application of contact-less and imaging, nondestructive test methods. However, it has to be proven first that these methods yield reliable data even under harsh conditions in tunneling. Thermography has indicated defects and in-homogeneities in waterproofing layers in other areas of applications (such as e.g., bridge constructions). The feasibility of using thermographic methods or other nondestructive test methods, eventually in combination shall be evaluated under laboratory and (if the second phase of the project will be approved after the first year) also under tunnel conditions.
Objectives:
The main aim of the project is to prepare a feasibility study on the use and applicability of thermography methods for quality control of mainly hand welded seams of polymeric waterproofing membranes for applications in, e.g., tunneling and other areas.
Methodology:
The use of thermographic methods to seals in general and specifically on geo-membranes in bridge and road construction has been investigated and delivered there in field trials evidence of defects or in-homogeneities. Preliminary tests in the laboratory to tunnel sealing systems of the AlpTransit construction project has also shown that larger adherent or non-adherent points of welds of plastic waterproofing membranes can in principle be distinguished with thermography. Before use in tunnel conditions but the process and the individual test parameters may have been optimized depending on the system and the detection limits are determined. Different combinations of materials, complex geometries and varying ground conditions and environmental factors are factors whose impact on the feasibility are still unknown.
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