668 Silicone Concrete Joint Sealant Low Modulus Class 50
silicone concrete joint sealant Low Modulus Class 50
GB 668 is specially designed for the lasting weatherproofing seal of concrete joints. Because of its low modulus and excellent extension and compression recovery (+100/-50 percent of original joint width), GB 668 exhibits outstanding performance in highway, airport, bridge and other concrete joints where high movement occurs. Accelerated weather aging test proves that GB 668 is definitely qualified to withstand the temperature extremes and strong violet rays of concrete pavement. Once exposed to moisture in the air, GB668 begins its room temperature cure to form an elastic silicone rubber with lasting weatherproofing seal performance.
FEATURES
One part,ready to use as supplied ,good gunnability, dispensed directly from container into joints by hand or with an air-powered pump
Excellent unprimed adhesion and bonding to concrete
Highmovementcapability-able to accommodate the extension and contraction, and shear deformation of concrete joints without itself being destroyed
Lowmodulus-abletostretchinthejointwithlittleforce.Thiscan better protect the concrete surfaces from being damaged
Resilient-oncecured,stronganti-embeddingperformance,preventing gravels and other incompressible into the joints which may result in joint edge failure
Highlyelasticityandextensionrecovery-thesealantcanbestretchedto 100 percent or compressed to 50 percent of the joint width. When released, it will resume its original shape without splits or cracks
Excellenttemperatureextremeresistance-curedGB668hasastable performance over the temperature range from -60°C to +150°C
Excellent lasting weatherability-the Si-O-Si high energy bond can not be destroyed by UV or ozone
TYPICAL PROPERTIES
These values are not intended for use in preparing specifications.
| Test Method | Property | Unit | Result |
| GB/T 13477 (ASTM D 2377) | Tack free time | min. | 60 |
| GB/T 13477 (ISO 8394) | Extrusion rate | ml/min. | 180 |
| GB/T 531 (ISO7619) | Hardness | Shore A | 30 |
| GB/T 13477 (ISO 8339) | 100% modulus | MPa | 0.4 |
| GB/T 528 (ISO 37) | Elongation at break(dumbbell type) | % | 600 |
| GB/T 13477 (ISO 11600) | Movement capability | % | +100～-50 |
| ASTM C793 | Aging resistance | Qualified | |
| GB 18583-2008 | TVOC | g/L | 53 |
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*GB: Chinese National Standard ASTM: American Society for Testing and Materials ISO: International Standardization Organization
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LIMITATIONS
GB 668 should not be applied:
In totally confined spaces as sealant requires atmospheric moisture for cure
To frost laden or damp concrete surfaces
When substrate surface temperature is below 4℃ or over 40℃
New concrete should be allowed to cure and dry for at least 28 days of good drying weather. For each day of rain that occurs during that period, an additional day should be added to the 28-day drying time. For fast completion and or high early concrete
mixes, please contact GB Technical Services
The sealant bead should be recessed below the surface of concrete surface to prevent abrasion from traffic and snow removal equipment.
The adhesion to substrates other than concrete should be checked before performing full-scale sealing.
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