Key Joint Filler

KEY RESIN #780 is a 100% solids flexible epoxy joint filler used to protect saw-cut joints in concrete slabs on grade or repair existing damaged joints. KEY RESIN #780 absorbs the impact and shock of heavy loads and steel wheeled traffic, preventing erosion of control joint edges.

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SKU: 780 Category:
Mixed Viscosity2200cps
Mixing Ratio1 Part A to 1 Part B by Volume
Solids Content100%, by volume
Volatile Organic Content (VOC)-0-
Weight per Gallon Mixed10.50lb/gal
Pot Life40 minutes at 75F
Dry to Touch6 to 8 hours at 75F
Re-Coat8 to 10 hours at 75F
Sanding Time24 to 48 hours at 75F
Full Cure & Maximum Resistance48 to 72 hours
Artificial Weathering (ASTM G23-75 Type D)10 to 15% elastomeric property change after 1,000 hours
Bond Cohesion after Water Immersion (Fed. Spec. TT-S–00227E)No Failure After 25% Total Movement
Tensile Strength (ASTM D-638)600psi
Ultimate Elongation (ASTM D-638)100%
Tear Resistance (ASTM D 624-73)30lb/in
Service Temperature30 to 180F
Key Advantages
  • Easy 1 to 1 Mixing Ratio
  • Ultimate Elongation of 100%
  • Low Odor During Application and Cure–Can be Used in Occupied Facilities
  • Cures on Damp/Wet Surfaces
  • USDA Approved
Key Considerations
  • Substrate temperature must be a minimum of 50F
  • Substrate must be free of dirt, waxes, curing agents, and other foreign materials
  • Should not be installed on new concrete (at least 30 days after placement)
  • Should not be used as an expansion joint material
Composition100% Solids Epoxy Resin with Aliphatic Amines
Surface Preparation
Surface Preparation is the most critical portion of any successful resinous flooring system application. Remove all curing compounds, sealers, and any other foreign substances from joints. Immediately prior to applying KEY RESIN 780, remove all water and dust from all surfaces with an oil free air blast. Work must be performed by trained or experienced contractors or maintenance personnel. The KEY RESIN COMPANY service department is pleased to answer any questions.
Mixing & Installation
KEY RESIN 780 is mixed by combining equal parts by volume of Part A and Part B. Pre-mix each component prior to combining. Mix combination with a low speed drill for a minimum of three minutes.
KEY RESIN 780 can be poured from a suitable container or applied with a caulking gun. Two passes may be required, as pourable materials have a tendency to dish out. The filled joint MUST be flush with the floor. For complete installation instructions, contact your Key Representative or Key Resin Company’s Technical Service.
Clean UpClean skin with soap and water. Tools and equipment should be cleaned with xylene or lacquer thinner before KEY RESIN 780 gels.
Key Resins are available throughout the United States, Canada, and a number of other countries. Contact the KEY REPRESENTATIVE in your area for details.
KEY RESIN 780 is typically installed as a joint material for Key Flooring Systems. However, if needed, KEY RESIN 780 is easily cleaned with neutral soaps or detergents. Routine mechanical scrubbing is recommended for all surfaces having a non-skid texture.
Technical Service
Key Resin Company and KRC Associates, Inc. provide services and consultations on material selection, specification, troubleshooting, and other information on the proper repair and protection of concrete surfaces. KEY REPRESENTATIVES are available to assist you at any time.
Key Resin Company (“”Key””) warrants for a period of one (1) year that its products will be free of manufacturing defects and will be in conformity with published specifications when handled, stored, mixed and applied in accordance with recommendations of Key. If any product fails to meet this warranty, the liability of Key will be limited to replacement of any non-conforming material if notice of such non-conformity is given to Key within (1) one year of delivery of materials. Key may in its discretion refund the price received by Key in lieu of replacing the material. No customer, distributor, or representative of Key is authorized to change or modify the published specifications of this warranty in any way. No one is authorized to make oral warranties on behalf of Key. In order to obtain replacement or refund the customer must provide written notice containing full details of the nonconformity. Key reserves the right to inspect the non-conforming material prior to replacement. EXCEPT FOR THE EXPRESSED WARRANTY STATED ABOVE, THERE ARE NO OTHER WARRANTIES, EXPRESSED OR IMPLIED, INCLUDING WITHOUT LIMITATION, ANY IMPLIED WARRANTY OF MERCHANTABILITY OR FITNESS FOR PURPOSE. KEY’S OBLIGATION SHALL NOT EXTEND BEYOND THE OBLIGATIONS EXPRESSLY UNDERTAKEN ABOVE AND KEY SHALL HAVE NO LIABILITY OR RESPONSIBILITY TO THE PURCHASER OR ANY THIRD PARTY FOR ANY LOSS, COST, EXPENSE, DAMAGE OR LIABILITY, WHETHER DIRECT OR INDIRECT, OR FOR INCIDENTAL OR CONSEQUENTIAL DAMAGES.

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