Rapid Flex CJ – Control Joint Filler

Rapid Flex CJ is a rapid-curing, UV-resistant polyurea control joint filler built for fast turnaround on industrial concrete floors

Rapid Flex CJ is a 100% solids, two-component, semi-rigid polyurea that cures quickly for fast joint shaving, meeting ACI 302 section 4.10 recommendations. It's also effective for repairing damaged joint nosing and cracks.

Key Features & Benefits

• Simple 1:1 mixing ratio with a pourable, pumpable consistency
• UV-resistant, maintaining color integrity (Dovetail Gray when mixed)
• High elongation rate (200%) minimizes tearing from movement
• Semi-rigid flexibility without welding slabs together or becoming brittle with age
• Ideal hardness (Shore A 85) supports wheel load transfer while allowing moderate movement
• USDA accepted; additional architectural colors available

Application Instructions

• Surface Preparation

  • Joint Cleaning: Ensure joints are clean, dry, and free of curing compounds, densifiers, sealers, or any other foreign substances. Use a vacuum-equipped dry-cut abrasive blade and oil-free compressed air to remove water or dust before application.
  • Joint Depth: Install Rapid Flex CJ full depth in sawcut control joints and at least 2 inches deep in joints greater than 2 inches. Avoid using compressible backer rod in sawcut control joints. In construction joints, dry sand or backer rod can be used to reduce volume while maintaining a minimum 2-inch depth.

  Mixing and Application

  • Mixing Instructions: Ensure Rapid Flex CJ components are at least 50°F for mixing. Stir or shake each component before dispensing. Use a 1:1 ratio, low-pressure duplex/plural component metered pump with a 3/8” x 24” static mixer.
  • Application Process: For cartridge or plural component pump applications, dispense mixed material into a waste container first to ensure uniform color and consistent 1:1 ratio. Then, dispense properly mixed Rapid Flex CJ into the prepared joint. Overfill joints and allow to cure for about 1 hour, up to 24 hours before shaving flush with the floor using a razor scraper.
  • Curing and Shaving: Rapid Flex CJ sets quickly, reducing the risk of staining joint sides. If installed before maximum concrete shrinkage, a crack may appear, which can be refilled with Rapid Flex CJ after cleaning with SpecChem Solvent 100.

Packaging

Available in 22 oz cartridges and 10-gallon units.

Supporting Documents

Safety Data Sheet (SDS)

Technical Data Sheet (TDS)

Shelf Life

Rapid Flex CJ should be stored in its original containers, kept tightly closed between 55-90°F, ensuring a shelf life of one year from the date of manufacture.

Standards

• Approved for use in USDA, FDA, and CFIA regulated environments
• Complies with ACI 302 guidelines for “Floor Joint Filler”
• 100% solid content, VOC-free, and LEED compliant