External water-proofing wrap for concrete structures
High Performance Water-Proofing Membrane for Concrete Structures

MarMac SealWrap is a high performance, water-proofing membrane used for sealing the joints of concrete structures. SealWrap is produced in easy-to-transport and store rolls. SealWrap is designed to be heavy duty compared to other sealing membranes because it is reinforced with an internal layer of woven polypropylene for puncture and tear resistance. It is not appropriate for use over expansion joints or joints that move.

Features & Benefits
  • Aggressive tack & initial adhesion to all concrete surfaces
  • Continuous adhesion after backfill
  • Puncture & tear resistant
  • Infiltration & exfiltration proof
  • Resistant to drying, oxidation & hardening
  • Primer not typically needed
  • Economical & effective
  • Available in a range of widths & lengths
MarMac SealWrap For Concrete Structure Joints Graphic

SealWrap meets or exceeds all requirements of ASTM C877, with the exception of Type lIl scope only covering butyl-based mastics and does not set material specs for bitumen-based mastics. MarMacʼs mastic exceeds the material specs set forth in C877 Type II which addresses the standard for rubberized asphaltic mastic.

Parts of ASTM C990 are commonly referenced for exterior wraps. SealWrap meets the physical requirements for Bitumen Sealants with the exception of the softening point. MarMacʼs mastic softening point is, by design, much lower (175°F) than the specified 320°F. Our material is designed for limited and controlled softening at any temperature above 40°F to achieve a unique initial tack strength and so the material continuously bonds with the concrete’s porous surfaces.

SealWrap should be stored in its original packaging, out of direct sunlight, protected from the elements. Material should be kept away from direct heat, sparks and open flame. For optimum results, couplers should be stored in a tepid (60-80°F) environment prior to installation.

Ash-inert matter 8% 15%
Volatiles 0.1% 2.0%
Softening temp 175°F
Specific gravity 0.95 1.05
Penetration 60 dmm 90 dmm
Flow 10 mm 10 mm
Tensile strength 4000 psi
Elongation at break 100%
Tear resistance 1500 psi
Water absorption 0.01%
The surface of the structure to be sealed should be clean of dirt and debris. The surface should be as dry as possible in field conditions. Specified width of wrap shall be placed against the structure, mastic side to the structure, spanning the joint to be sealed. The protective release film shall be removed from the edge of the wrap and be applied to the structure wall centering the joint gap. Continue to remove the release film as the wrap is applied in full circumference, while keeping hand tension to prevent wrinkling, ensuring adhesion and alignment. The wrap should overlap itself a minimum of three inches (3″) with the overlap at the top of the pipe in an accessible position. Hand press the overlapped edges to ensure a seal.


9″, 12″ & 14″ width rolls
Repair kit available
*Custom widths (up to 36″) & roll lengths available upon request.


Reinforced Concrete Pipe
Box Culverts
Detention & Burial Vaults
Tornado Shelters

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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.