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The Quality Control of Silicone Structural Sealant during Construction (2)
There are four tests for construction quality control of construction silicone sealant: butterfly test, pull-off time test, factory peel-off adhesive test, tapping test. The previous Baiyun online article introduced the butterfly test and pull-off time test in detail; today we continue to give you details on the factory peel-off adhesive test and tapping test.
First, peeling adhesive test
For different construction environments, different batches of aluminum, glass and structural adhesives, etc., in order to ensure the stability of the adhesive, it is necessary to carry out the structural adhesive peel adhesion test with the approval. And the curing conditions of this adhesive test must be consistent with the actually produced curing conditions, so as to avoid inconsistent adhesion results due to differences in temperature and humidity.
1. Clean the substrate surface, apply a primer (if necessary), and apply an anti-adhesive tape on one end.
2. Apply a proper amount of sealant on the surface of the substrate, length> 20cm, width> 20cm, thickness 3-6cm, and at least 5cm long sealant should cover the release tape.
3. Trim the sealant to ensure that the sealant completely conforms to the bonding surface.
4. In the curing period of 3-21 days (the time required for the general two-component structural adhesive is short and the time required for the one-component structural adhesive is long), the sealant is pulled at a 180 degree angle every day and tapped to check the cohesive failure area of the substrate surface. In case of confirming whether it is well bonded or not, how long it takes to maintain it.
5. If the cohesive failure on the surface of the substrate (see figure b below) after peeling off the sealant is above 95%, the adhesion test is acceptable.
6. If the sealant fails to adhere to the substrate (see a), stop immediately and look for the cause.
Peel adhesion test can timely monitor the structural adhesive and the substrate for abnormal adhesion. During the test, if we find poor adhesion, we should immediately stop the construction and find out the reason. Poor bonding of the structural adhesive will directly affect the safety of the curtain wall. The reasons for the failure of the peeling adhesion test are: differences between substrates or glue batches, large environmental changes, and short maintenance times. We need to solve the problem of poor bonding of structural adhesives in time to avoid problems found after large-scale construction, reduce losses, and ensure the safety of curtain walls.
Second, the finished unit unit tapping test
Check the construction quality and bonding quality of the single-element finished product structural glue.
1. Randomly selected units have been maintained. The sampling frequency is generally as follows: 3 for the first 100 units and 1 for every 100 units.
2. Cut the adhesive surface of the glass and aluminum frame with a cutter to leave the structural adhesive on the glass or aluminum frame.
3. After the glass and aluminum frame are completely separated, measure the width of each cut point with the ruler and the thickness of the liner material used.
4. Make sure that the adhesive bonding width and thickness, adhesive width, and the liner material are not bonded to each other. Check the gel hardness, color, and whether there are bubbles or cavities.
5. Confirm the adhesiveness between the structural adhesive and the substrate: Use the pull-pull test method, cut a small amount of structural adhesive along the adhesive surface of the substrate, and then forcefully pull at an angle of 180°C to see if there is a bond failure area; No obvious bond failure, the tool can be used to cut the adhesive surface and repeat the above hand pull test process several times.
6. If the width and thickness of the structural adhesive meet the design requirements, there is no adhesion with the liner material, the hardness and color are normal, there are no voids and bubbles, and the cohesive failure area of the base material exceeds 85%. We believe that the structure of the single element The glue construction quality is qualified.
7. If there are any indicators that do not meet the qualification requirements, we need to stop construction immediately to find out the reasons. Confirm that there is a problem and need to be reworked.
The tapping test of the finished unit piece is a test to confirm the final construction quality of the structural adhesive. Only after the qualified tapping test of the finished unit parts can the unit parts be delivered to the site for installation.
In the tapping test, the common problems are: the width of the structural adhesive is not qualified, the local injection is not full, there are bubbles and cavities, the adhesive cohesive failure area does not reach 85%, the colloidal color is shallow, and the mixing is uneven. When the failure of tapping test is met, it shall be traced according to the construction record and the sampling frequency shall be increased.
The two Baiyun online articles introduced the four tests for the construction quality control of structural adhesives. We believe that everyone understands how to control the construction quality of structural adhesives. In the actual construction process, construction quality control must be strictly in accordance with requirements to ensure the quality and safety of the project.
The quality control test of the above four architectural silicone structural adhesives is an important method to ensure the construction quality of structural adhesives. In the structural rubber construction project, we must do these four tests to ensure that every single unit is safe and permanent on the building curtain wall!