Expansion Joints and Pre-Compressed Sealants

Chemical-Resistant, Structural Expansion Joint and Construction Joint Sealant

CHEMSEAL Expansion Joint Picture

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Additional Data:

CHEMSEAL Chemical Resistance Chart





EMSEAL Recommends: Submerseal is recommended for use in most submerged applications. Its single bellows construction and increased silicone thickness makes it ideally suited to accommodate the significant head-pressure of continuous submersion. While CHEMSEAL's polysulfide surface bellows offer resistance to a wider range of chemical solutions, the use of polysulfide instead of silicone requires a more complex product construction and application process which increases installation time and procedures. When not limited or prohibited by contact with extraordinary chemical composition, EMSEAL recommends considering Submerseal for all applications requiring continuous immersion in chlorinated water and other liquids.

CHEMSEAL is a chemical-resistant,
joint-face-adhered, precompressed, primary seal for retrofit and new structural expansion joints and construction joints where contact with chemicals and chemical dilutions is expected.

The CHEMSEAL line of products is tested in a hydrostatic-head pressure simulator to continuously resist water pressure of various levels without product deflection or leaking. Consult EMSEAL for status and for applications involving your particular expected head pressures.

CHEMSEAL builds on a track record of over 30 years of sealing structural expansion joints with impregnated foam sealants and is an evolution of EMSEAL's DSM SYSTEM.

Microsphere-modified-acrylic-impregnated foam sealant, factory pre-coated with chemical resistant polysulfide sealant. Watertight, clean handling, UV stable, non-staining, low temperature flexible, high-temperature stable.

The polysulfide coating is SynthacalkTM GC2+ and is resistant to the effects of sunlight, rain, snow, ozone, aging, shrinkage, and daily and seasonal cycling changes caused by temperature fluctuation.

Standard sizes from 1/2" to 2" (12mm to 50mm) for applications under constant submersion up to 5-feet of head pressure. For larger sizes up to 4" (100mm) contact EMSEAL to determine conditions and application.

Note: Sizes under 1 1/2" (40mm) are manufactured with a single bellows. Larger sizes incorporate multiple bellows.

Movement Capability
+25% and -25% (Total 50%) of nominal material size.


Manufactured to resist the harsh conditions found when expansion systems contact non-purified water or liquid-suspended chemicals. Some examples are:

Waste Water Tanks Chlorinated Water
Spill Containment Fountains
Industrial Testing Tanks Pools
Cooling Towers Water Parks & Water Features
Product Description
Featuring a polysulfide-bellows sealing surface and backed by an integral, pressure-resisting impregnated foam backing, CHEMSEAL+5 provides a lasting solution to joint sealing applications involving chemicals or chemical dilutions.

The system is comprised of (see Figure 1) precompressed, polysulfide-and-impregnated-foam hybrid installed into field-applied epoxy adhesive on the joint faces with the polysulfide bellows locked to the joint faces with a field-applied polysulfide sealant band.

CHEMSEAL+5 features EMSEAL’s microsphere-modified acrylic impregnation infused into the cellular foam base material.

Figure 1: CHEMSEAL+5 SYSTEM in Typical Installation (Single-sided)



Chemical Resistant:  See Chemical Resistance Chart

Watertight — CHEMSEAL+5 is installed with the tensionless polysulfide bellows facing the liquid ensuring that watertightness is achieved.

Non-Invasive Anchoring — there are no hard metal-to-substrate connections with CHEMSEAL+5. This includes embedded pins, anchors, screws, bolts or tracks, trays or rails. The system is locked to the joint faces by means of the 1) backpressure of the foam; 2) the epoxy adhesive, and 3) the injected polysulfide sealant band at the joint face to foam-and-polysulfide-bellows interface.

Movement Capability +25% and -25% (50% total) of nominal material size. (See "Performance")

Versatility — The standard CHEMSEAL+5 color is gray. Uniform bellows appearance, chemical resistance, and ability to handle variations in joint size through size-switching are among other system features.

US Patent 9,200,437 Patent Pending
Expanded Universal-90's information)

Continuity of Seal
— as in all EMSEAL expansion joint systems, continuity of seal through changes in plane and direction is an essential performance differentiator. CHEMSEAL+5 is manufactured in straight-run sticks which are joined in the field with EMSEAL’s exclusive "Universal- 90’s" which are factory-fabricated single-piece 90-degree units. In addition to guaranteeing watertightness, EMSEAL’s "Universal-90’s" allow for much faster and secure installation by eliminating field cutting at angles. And because they are coated on both sides they can easily be installed at inside and outside corners as needed.

Figure 2: EMSEAL’s warranted watertight, factory-fabricated Universal-90’s at inside and outside corners ensure continuity of seal while eliminating field execution of directional changes.

"Universal-90", Factory-Fabricated Transition Pieces from EMSEAL ensure continuity of seal in expansion joints.


Double-Sided Straight-Run Option — CHEMSEAL+5 is also available with double-sided protection manufactured with the chemical-resistant bellows on both sides of straight lengths for use in applications where contamination from two sides is possible. (See Figure 3)
Figure 3: CHEMSEAL+5 SYSTEM in Installation Where Contamination from Both Sides is Possible (Double-sided)


Capable of movements of +25%, -25% (50% total) of nominal material size.

CHEMSEAL+5 will maintain its watertight capabilities and shape under a constant submerged depth (hydrostatic pressure) of up to 5 feet.

Standard sizes from 1/2" (12mm) to 4" (100mm). Other sizes available subject to review of application. Consult EMSEAL.

Substrates must be solid, parallel, plumb and capable of resisting approximately 2.5 psi backpressure from the foam.

Chemical Resistance: The polysulfide sealant is not degraded by contact with many chemicals. (See Chemical Resistance Chart)

Applicable Standards: The polysulfide coating meets or exceeds all aspects of Federal Specification TT-S-00227E, Type II, Class A in all respects except Section 3.5.7, “Stain and Color Change”, ASTM C920, Type M, Grade NS, Class 25, Use NT, M, G, A with the exception of ASTM C510 “Stain and Color Change”. Also exceeds the test requirements of ASTM C1247 for sealants exposed to continuous immersion in liquids and NSF Standards 61, Section 6 for Joining and Sealing Materials.


• CHEMSEAL+5 is produced by coating an impregnated cellular foam with a chemical-resistant polysulfide liquid sealant.

• The polysulfide external facing is factory-applied to the foam at a width greater than the maximum offered extension and is cured before final compression.

• Polysulfide application and curing takes place in a factory-controlled environment. In contrast to field-applied liquid sealant and backer rod installations, no movement takes place during curing that can cause deformation or stresses in the material.

• When compressed, a bellows is created in the coating. As joint movement occurs the bellows simply folds and unfolds free of tension on the bond line, and virtually free of tensile stresses in the polysulfide material.

• The foam provides a resilient backing to the polysulfide coating, making the system capable of resisting head pressure and reasonable transient point loads.

• CHEMSEAL+5 is supplied in 6.56 LF (2m) shrink-wrapped lengths (sticks). "Universal-90" factory-fabricated corners with a standard length of 6-inches (one leg) and 12-inches (other leg) are also available and are required for executing transitions in plane. CHEMSEAL+5 is precompressed to less than the joint size for easy insertion. After removal from the shrink-wrap and hard board restraining packaging, it expands gradually.


IMPORTANT: The following instructions are a summary. Refer to "CHEMSEAL Install Data" and job-specific instructions of an EMSEAL technician for complete procedures. FOR PROFESSIONAL USE ONLY. KEEP OUT OF REACH OF CHILDREN.

• Store indoors at room temperature. Expansion is quicker when warm, slower when cold. Substrate temperature must range between 50deg.F (10deg.C) and 110deg.F (43deg.C).

Shelf Life: One year in original unopened packaging stored at temperatures not to exceed 80-deg.F (26deg.C)

• Precautions: Wear chemical-resistant gloves and/or barrier hand cream when handling liquid polysulfide sealant or epoxy. Remove promptly from skin with a commercial hand cleaner before eating or smoking. Avoid inhaling vapors.

• Sequencing: Install factory-fabricated transition and/or termination pieces first. Connect straight run material to in-place terminations and transitions. Cut closing pieces 3/8-inch (10mm) longer than the opening to be joined. Compress material longitudinally to fit.

• Ensure nominal material size matches joint size.

• Mix epoxy and trowel a thin layer onto the joint faces to at least the depth of the CHEMSEAL+5 foam.

• Remove shrink-wrap packaging, hardboard.

• Wipe polysulfide facing using clean lint-free rag made damp with solvent.

• Insert material into joint to determined depth below the substrate surface such that the tops of the bellows are essentially flush with the substrate surface.

• The polysulfide liquid sealant is shipped in 1.5 gallon kits in two components. Thorough blending of the base and activator components is essential for optimum sealant performance. Remove the Activator (part A) from the Base (part B) container. Also be sure to remove the polyethylene sheet or tray from the B container. Before adding Part A, mix Part B with a mixing paddle with a low-speed, heavy-duty electric drill. Then add Part A to Part and mix for 6-minutes, or until the material is completely blended, scraping down the sides of the container and mixing paddle periodically during mixing. DO NOT mix base and activator components from one shipment with components from another. DO NOT divide or split a kit--The full 1.5 gallon kit must be mixed and the mixed sealant drawn up into a bulk gun from which it will be dispensed. The working time on a mixed kit is about 1 hour at 70-deg F. (21-deg C). Some wastage should be expected and extra kits may need to be ordered by the applicator depending on the total quantity, temperature at time of installation and staging of the work.

• Inject a band of liquid polysulfide between mating bellows’ faces.

• Join lengths by pushing polysulfide-coated ends firmly together.

• Before the epoxy or the mixed polysulfide cures, force the tip of the bulk gun cone between the foam and the substrate and inject a polysulfide sealant band. Tool the overflow sealant into a cover bead between the top of the polysulfide bellows and the substrate.

• Tool the polysulfide between joined lengths so that the bellows are not restrained by excess polysulfide.

NOTE: It is critical that any exposed foam ends or any other foam exposed during installation be field coated with the liquid polysulfide sealant supplied. The resilient foam backing is not resistant to chemical exposure.

• Clean Up: Remove polysulfide sealant from equipment before it cures using MEK*, Toluene*, or Xylene*. These solvents are not effective after the polysulfide has cured. Cured material may be removed by cutting it away with sharp tools, sandpapering or softening with chlorinated solvents*.

*(Solvents mentioned or referred to are toxic and flammable. Observe solvent manufacturer’s precautions and refer to Material Safety Data Sheets as well as local and federal requirements for same handling and use).

IMPORTANT Allow liquid polysulfide to attain a complete cure before filling area with liquid (7 days minimum).

• Maintenance: If the polysulfide bellows or sealant bands are damaged but remain intact, cut out the damaged area and recaulk. No primer is required. If the bond has been affected or the foam backing of the CHEMSEAL is compromised, remove the damaged area, clean and prepare the substrates in accordance with instructions and reinstall new material.

Availability and Price

CHEMSEAL+5 is available for shipment internationally subject to shipping restrictions for flammable and hazardous materials. Prices are available from local representatives and/or directly from the manufacturer. The product range is continually being updated, and accordingly EMSEAL® reserves the right to modify or withdraw any product without prior notice.


* TM- Synthacalk is a trademark of Pecora Corporation, Harleysville, PA

EMSEAL JOINT SYSTEMS LTD. 25 Bridle Lane, Westborough, MA 01581
EMSEAL LLC. 120 Carrier Drive, Toronto, ON M9W 5R1



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