Finnish demands divide geosynthetics committee.
Since one and a half year CEN/TC 189 and working group meetings are dominated by the Finnish demand to modify the existing mandate, which has been the basic document for the development of a set of ten application-related product standards on geotextiles. As a consequence all these standards should be revised without delay.
Meanwhile the Finnish have succeeded to take the first hurdle by obtaining effectively a new mandate, issued by the "standing committee for the construction sector", an European group of high public officials. The new mandate requires to include "elongation" as a mandatory parameter (needed for CE conformity marking) for the functions "separation" and "filtration/drainage", which at first sight seems a minor change.
However, several countries suspected that the rationale behind this request was to introduce the notion "absorbed energy" (a combination of elongation and tensile strength) in product specifications, which could be very disadvantageous to woven structures. At first instance there was a great reluctance in CEN/TC 189 to accept the new mandate, even more because no proper technical discussion had taken place within the TC before this new mandate was issued. Eventually the new mandate was accepted because CEN/TC 189 still had the responsibility and freedom to decide on the test method to assess elongation.
The dispute now focuses on the choice of the test method. For the Finnish (and for most other delegations) this is very simple: with each tensile test (measured with the wide-width test) the elongation at breaking load is also measured and it seems logical to use both data obtained in one single test. Other countries, such as the UK and Belgium, argue that measuring elongation really means measuring deformability, which is actually a multi-axial phenomenon. Hence they propose as an alternative to use the CBR-test, in which the material is stretched by a plunger in all directions until it breaks. To demonstrate the relevance of this method, comparative tests were presented, but both sides remained on their positions.
After extensive discussions in WG 1 (general requirements) no consensus could be reached and it was decided to ask technical advice from WG 3, the working group specialized in testing mechanical properties. Because the European Commission insists on an urgent reply to this topic an extra WG 3 meeting is called on 22nd June in Milan. The WG 3 advice will then be submitted to CEN/TC 189 by a postal ballot.
In the margin of all these mandate discussions draft standards were finalized on geotextiles used in asphalt reinforcement and on geosynthetic barriers used in transportation infrastructure. They will soon be forwarded to CEN for formal vote.
FF
2007-06-18
