Butyl Sealant

Butyl rope sealant for joints of concrete structures.
Premium-Grade, Butyl-Based Rope Sealant

MarMac Butyl Sealant C-990 is a premium-grade, preformed, butyl-based rope sealant designed to be permanently flexible, tacky, and resistant to moisture and to deterioration by exposure to dilute chemical solutions.

Features & Benefits
  • Meets or exceeds ASTM C-990 specification
  • Chemical resistant
  • Permanently flexible, including in cold weather
  • Fast & easy application, including in extreme weather conditions
  • No shrinkage, non-corrosive
  • No visual deterioration, will not oxidize or harden with age
  • No adhesion loss or cracking
  • Hydrostatic performance

Meets all requirements of ASTM C 990 Section 6.2. Meets requirements of AASHTO M-198 with the exception of flash point and fire point.

Not recommended for use in areas of concentrated oils or hydrocarbon solutions. Prior to working with MarMac Butyl Sealant C-990, consult the product label and Safety Data Sheet (SDS) for necessary health and safety precautions.

During testing method ASTM C 990 for chemical resistance, MarMac Butyl Sealant C-990 had no visible change after 30 days of immersion in 5% solutions of HCI, H2SO4, NaOH, KOH, or H2S. Upon testing in accordance with ASTM C 765, MarMac Butyl Sealant had no sag or shape change after 14 days when tested at 158°F for elevated temperature flow, and did not experience cracking or adhesion loss when tested at -10°F for low temperature flexibility.

MarMac Butyl Sealant C-990 should be stored in its original packaging (shelf life 2 years), out of direct sunlight, protected from the elements. Material should be kept away from direct heat, sparks and open flame. For optimum results, store in a tepid (60-80°F) environment prior to installation. Storage temperature should not exceed 120°F (49°C).

Service Temperature Range -40 °F 250 °F
Application Temperature 20 °F 120 °F
Color Black Visual
Specific Gravity 1.15-1.40 ASTM D 71
Hydrocarbon Content 50 % min ASTM C 990
Ash Content 45-48 % AASHTC T111
Ductility 6.0 cm ASTM D 113
Compression Index @ 77°F 44-55 lbf/in3 ASTM C 972
Compression Index @ 0°F 130-160 lbf/in3 ASTM C 972
Cone Penetration @ 77°F 55-85 lbf/in3 ASTM D 217
Solids Content 99 % min ASTM C 681

The surface of the structure to be sealed should be dry and clean of dirt and debris. Take roll of MarMac Butyl Sealant C-990 from case and avoid touching the sealant to dirt and other materials on the job site to ensure proper adhesion. Apply C-990 with exposed sealant against the concrete structure and apply around the joint without stretching. Cut to length and complete seal by butting the cut ends without overlapping and molding the ends together. Remove the protective release paper by peeling it away from the sealant. Set the joint properly with the sections aligned and straight. MarMac Butyl Sealant C-990 will adhere to the concrete surface and fill the annular space in a uniform manner between the tongue and groove when the pieces are properly joined.


0.75″ (8- 14.5′ rolls)
1.00″ (6- 14.5′ rolls)
1.25″ (4- 14.5’rolls)
1.50″ (4- 11′ rolls)


Septic Tanks
Box Culverts
Reinforced Concrete Pipe
Concrete Valves
Utility Vaults
Vertical Panel Structures

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*All statements and technical information are based on tests and/or data which MarMac Manufacturing deems reliable, however, MarMac does not warrant or guarantee the accuracy or completeness of such information. Please read further manufacturer liability and warranty information.