ISO 24068-2:2021 Building and civil engineering sealants – Determination of the degree of cure-Part 2: Build-up of tensile and adhesion properties in test joint specimens .
6 Preparation of test specimen
The sealant in its unopened package, the substrate pieces, and the spacers shall be conditioned at (23 ± 2) °C and (50 ± 10) % relative humidity for a minimum of 16 h prior to the preparation of the test specimens.
For each substrate type. each cure interval, and the reference cure (method A or B, see 7.2.2. ZZ.3 and Claiise8), three test specimens shall be prepared. Thus, a minimum of six test specimens are needed for the test (assuming the experimenter choses one substrate, one cure interval and one reference cure for the testing).
For multi-component sealants, the instructions of the sealant manufacturer regarding the mixing procedure shall be followed. One-component sealants can be applied directly from the original container.
For each test specimen, two substrate pieces (sd) and two spacers (52) shall be assembled in accordance with ISO 8339 and set on the anti-adherent substrate (5,3). Follow the instructions of the sealant manufacturer whether a primer is to be used.
Fill the volume between the substrate supports and spacers with sealant. The following precautions shall be taken:
a) ensure that no air pockets are entrapped in the sealant by filling the test joint cavity from the bottom; b) ensure that no leaks occur at the bottom of the test joint specimen;
c) trim the sealant surface so that it is flush with the faces of the substrate supports and spacers.
The test specimens shall he set on the edge of one of the supports. The anti-adherent substrate shall he removed as soon as possible. The specimens shall be placed in this position to allow curing or optimum drying of the sealant. The spacers shall be maintained in place during conditioning.
7 Conditioning of test and reference specimens
7.1 Conditioning of test specimens
The test specimens shall be conditioned (cured) for a specified period of time (cure interval) at standard conditions of (23 ± 2) °C and (50 ± 10) % relative humidity. One or several arbitrary cure intervals may be selected, as agreed by the parties concerned. Typically, cure intervals are selected from the following: 16 h, 24 h, 48 h, 72 h, 4 d (96 h), 7 d (168 h), 14 d (336 h).
7.2 Conditioning of reference specimens
7.2.1 General
The three reference specimens shall be conditioned either in accordance with method A (see 722) or method B (see Z2..3), or any other reference cure period or conditions (method C: custom) as agreed by the parties concerned.
7.2.2 Method A
The reference specimens shall be conditioned for 28 d at (23 ± 2) °C and (50 ± 10) % relative humidity.ISO 24068-2 pdf download.