Two-component Polyurethane Sealant for Joint Sealing

Description:

Comensflex 8277L is a two-component low modulus 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:
		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			%	≥80
6		Solid content			%	≥99
7		Hardness（23℃）			Shore A	25±5
8		Water impermeability			／	0.4Mpa, 2h
9		Elasticity modulus		25±2℃	Mpa	≤0.3
				-30±2℃		≤0.6
10		Tensile strength		Standard	Mpa	≥2.0
				condition
11		Elongation at break		Standard	%	≥800
				condition
12		Elasticity at low		Standard	-35℃	No crack
		temperature		condition
13		Bonding		Heat	60% definite	No breakage
		performance at		treatment	elongation

	definite elongation	Alkaline
		treatment
14	Bonding strength	Dry surface	MPa	≥1.0

• Construction Technology:
• 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 s est 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.

• Comensflex 8277L 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 8277L 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.

 

• 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.