Two-Component PU (Polyurethane) Sealant for Concrete Construction Joint Sealing (Comensflex 8279)

• Bonding Function: Structural Adhesive
• Morphology: Uniform Paste
• Application: Construction
• Material: Polyurethane
• Color: Black
• Levelability: Even and Smooth
• Model NO.: Comensflex 8279
• Application Time: ≥1 H
• Tack Free Time: ≤12 H
• Complete Dry Time: ≤24 H
• Elastic Recovery Rate: ≥70 %
• Uses: Construction Expansion Joint
• Hardness (23 ºC): 30±5 (Shore a)
• Mix Ratio: 5 : 1
• Tensile Strength: ≥1.0 MPa
• Elongation at Break: ≥700 %
• Transport Package: 22.5kga+4.5kgb Pail
• Specification: ISO9001, ISO14001
• Trademark: Comensflex
• Origin: Beijing, China
• HS Code: 3506100090
• Production Capacity: 30000 Tons/Year

Product Description

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.

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

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.

Technical Data

	Items		Unit	Data
1	Levelability			Even and smooth
2	Application time		h	≥1
3	Tack free time		h	≤12
4	Complete dry time		h	≤24
5	Elastic recovery rate		%	≥70
6	Hardness (23 ºC)		Shore A	30±5
7	Tensile Strength	Standard condition	Mpa	≥1.0
8	Elongation at break	Standard condition	%	≥700
9	Elasticity at low temperature	Standard condition	-35 ºC	No crack
10	Bonding performance at definite elongation	Heat treatment	60% definite elongation	No breakage
		Alkaline treatment

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.

Note
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.

Pad
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 8279 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 minute.

Note:
Comensflex 8279 is of two-component. The mixing ratio must be 5: 1 and assure uniformly mixed.

If there is sediment in component A, it does not affect usage. But component A must be well mixed before mixing with component B.

(3) Applying technology
Put the mixture (A&B) into a suitable container, and affuse into the expansion joint. The level of the affusion should be 2-5mm lower than the joint edge. 30mins after affusion, use a scraper (thinner than the joint) to scrape the surface of the sealant lightly to make the sealant in the joint to form the U section, which meanwhile can eliminate the bubble in the sealant.
After working, no water can be put into the sealant within 24 hours.

Note:
(1) The work must be done at appropriate temperature.
(2) The consumption is different according to the depth of the expansion joints.
(3) The sealant must be applied in working time, or the work will be affected.
(4) The sealant must be conserved for at least 24hs at the humidity less than 80%RH, temperature 5-40 ºC.
(5) It does not affect usage if there is slight bubble or bulge after the sealant curing.
(6) The movement capability is 25LM, that is to say the deflection of the expansion joint should be less than 25% of the expansion joint.

Packaging
Comensflex 8279A:22.5kg/pail,
Comensflex 8279B:4.5kg/pail.
1 part Comensflex 8279A match with 1 part Comensflex 8279B

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 9 months, 8279B is 12 months.

Note
The sealant working time and curing rate are affected by the surrounding conditions. If the
temperature is low, the working time and curing time is longer, and the viscosity will be higher;
if the temperature is high, the working time and curing time is shorter; if the temperature is too
high, there will be bubbles in the sealant. The appropriate temperature is 5-40ºC, humidity is
lower than 80%. If the sealant is tacky or soft, it may caused by too high humidity or not
enough curing agent.


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