28. 10. 2022


Silylated adhesives for bonding parquet to subfloor

On June 9, UNI published the standard "UNI 11864: 2022 Building adhesives - Adhesives for bonding parquet to subfloor - Silylated adhesives, thermal stability test - Test method and requirements " this technical document arises from the work carried out by the members of the group “GL 04 adhesives for general use in construction” of UNICHIM (a body federated to UNI which deals with unification in the chemical sector).
It was a real team work as the companies involved made their laboratories available for the implementation of interlaboratory testsaimed to define the most effective test method for verifying and assessing the performance of these particular adhesives types that, in some cases in use, had shown problems promptly resolved by the industrial sector, but not pointed out by the tests provided by the international standard: "EN ISO 17178: 2020 Adhesives - Adhesives for bonding parquet to subfloor - Test methods and minimum requirements". The results of the tests performed, thanks to the UNICHIM’s expertise, were also analyzed from a statistical point of view to assess their robustness.
The standard specifies a test method to assess the thermal stability of a silanic termination adhesive for bonding parquet and/or wood floors in general to a substrate. It also specifies the requirements to be overcome with this type of adhesives. This Standard can be included as a durability determination test in addition to ISO 17178, which defines the minimum requirements for adhesives for bonding parquet floors.
The test procedure provides gluing oak wood elements on the surface of a standardized screed and determining the tensile strength perpendicular to the surface of the support after respectively:
  • conditioning in a standard atmosphere (23 ° C and 50% r.h.) for 49 days
  • high temperature conditioning (7 days at 23 ° C and 50% r.h. + 41 days at 90 ° C + 1 day at 23 ° C and 50% r.h.)
The standard provides a requirement for which the percentage variation, between the average value of the tensile strength after elevated temperature conditioning and after conditioning in a standard atmosphere, shall be greater than 85%.
The assessment of the consistency of the data that led to this requirement was managed directly by UNICHIM, the working group considered useful to share this approach with the users of the standard, and this information was collected in the informative annex. Perhaps, consulting this document from the end, i.e. by reading the informative appendix first and then the normative text, could be an excellent starting point to better understand its philosophy and technical value.

For info:
Paolo Tirelli