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Comensflex 8279 Two-component Polyurethane Sealant for Joint Sealing
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  • Comensflex 8279 Two-component Polyurethane Sealant for Joint Sealing
sku: Comensflex 8279
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Comensflex 8279

Two-component Polyurethane Sealant for Joint Sealing

1. Description
Comensflex 8279 is a two-component polyurethane sealant for various joint sealing, which owns
the features of high elongation and good elasticity after A and B mixing. It is a high-performance
polyurethane material for sealing and waterproofing for construction.

2. Uses
Concrete construction expansion joint, expansion joint of railway, airport runway, and
highway/railway bridge.

3. Characteristics
Easy to apply, high solid content, high elongation, good water resistance, excellent durability and
fatigue resistance. Its service life is much longer than asphalt joint sealant. The sealant is of high
bonding strength, with no trickling at summer time or hardening and cracking at winter time. It
keeps an elastomer permanently, which is effective sealing and waterproofing.

4. Technical Data
Comensflex 8279

Items Unit Data
1 Levelability Even and smooth
2 Application time h ≥1
3 Hardness(23℃) Shore A 30±5
4 Tack free time h ≤12
5 Elastic recovery rate % ≥70
6 Complete dry time h ≤24
7 Tensile strength Standard condition Mpa ≥1.0
8 Elongation at break Standard condition % ≥700
9 Elasticity at low temperature Standard condition -35℃ No crack
10 Bonding performance at
definite elongation
Heat treatment

60% definite


No breakage
Alkaline treatment

5. Construction Technology:
(1) Preparing Work
Expansion Joint Clearance
The expansion joint should be dry and clean with no sundries such as foam and matchwood,
etc. Clear away the quicksand and oil. If necessary, clear away the sundries and quicksand
with blower.
The clearance of the expansion joint is a factor of the good performance of the sealant. The
wet or dirty expansion joint will cause bulge or falling down of the sealant. And the oil or
dust will impact the bonding effect. Thus, there will be separation between the sealant and the
surface under the cold condition. Comens will not shoulder the responsibility if there is
quality problem due to the uncleaness of expansion joint.
According to the need, we usually suggest to use the PE pad under the joint, to avoid stress
concentration due to bonding on three sides. The diameter of the round pad should be bigger
than the 25% width of the expansion joint to avoid leakage of the sealant.
(2) Comensflex 8279L is packed with the ratio of 5:1. Mix uniformly before applying it. Put
the component B into A, then mix with the mixer (around 300rpm, cannot be mixed
manually). Mix for at least 3 minutes to assure the materials uniformly mixed. (Note:
scrape the adhering material deposited on the side or bottom of the drum). Put the
mixture into a new container according to the consumption, then mix for one more

6. Packaging:
Comensflex 8279A:25kg/pail,
Comensflex 8279B:5kg/pail.
1 part Comensflex 8279A match with 1 part Comensflex 8279B

7. Storage and shelf life:
Store in a cool and dry place. Avoid direct sunlight. If stored at the recommended conditions
in original, unopened containers, the shelf life of 8279A is 9months, 8279B is 12months.
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