Hairline to fine concrete cracks compromise structural integrity. ARDEX RA 142's super low viscosity (190 cps) penetrates even the tightest 0.05mm cracks. It structurally fuses concrete for lasting repair, restoring monolithic strength.

Why this product exists

Concrete structures often develop hairline to fine cracks. These micro-fractures can impact the long-term durability and load-bearing capacity of a slab or element. ARDEX RA 142 is a two-component, solvent-free epoxy adhesive engineered for the structural repair of these dormant concrete cracks, from 0.05mm to 3mm wide. Its formulation ensures deep penetration for both gravity-feed and pressure injection applications, making it suitable for restoring the integrity of horizontal and vertical concrete surfaces. It also serves as a robust bonding agent for concrete and forms a high-strength mortar for spall repair when mixed with aggregate.

The numbers that matter

  • Mixed Viscosity: 190 cps. This super low viscosity allows ARDEX RA 142 to penetrate cracks as fine as 0.05mm. It fills the entire crack profile, ensuring a complete and structural bond even in the tightest fissures.
  • Compressive Strength: 70 MPa (7 days). Once cured, this epoxy develops exceptional compressive strength. This effectively restores the monolithic strength of the concrete, preventing further deterioration and maintaining structural performance.
  • Shear Bond Strength: 11 MPa (7 days). A high shear bond strength ensures ARDEX RA 142 creates a tenacious bond between the crack faces or between new and old concrete. This resistance to shearing forces prevents delamination and ensures long-term repair stability.
  • Gel Time: 20 minutes (at 24°C). A 20-minute gel time provides adequate working time for application, especially during complex injection procedures. It ensures the epoxy can be fully placed before curing begins, while still allowing for efficient project completion.

What it's like to use

ARDEX RA 142 comes in a dual cartridge system, simplifying mixing and dispensing. Proper surface preparation is critical: concrete must be clean, dry (for best results), and mechanically roughened for optimal adhesion. For vertical crack injection, ARDEX RA 88 is the recommended capping paste to secure injection ports and seal the crack surface, forming a complete system. Maintain ambient and substrate temperatures between 10°C and 35°C. Lower temperatures will slow the cure, while higher temperatures accelerate it. Clean tools immediately after use with white spirits or mineral turps before the epoxy hardens.

Where this product excels

  • Civil Construction: For structural repair of dormant hairline to fine cracks in concrete bridge decks, columns, and beams, restoring the load-bearing capacity of these critical elements.
  • Flooring & Masonry: As a high-strength bonding agent for pre-cast concrete elements or for repairing spalls and shear fractures in concrete slabs, particularly in industrial or commercial settings.
  • Waterproofing: Preparing concrete substrates by structurally repairing dormant cracks before the application of waterproofing membranes, ensuring a stable and intact base for long-term system performance.

How it fits in a real system

ARDEX RA 142 is a core component of the Ardex concrete repair system for structural crack injection. When addressing vertical cracks, it works in conjunction with Ardex RA 88 Plus Multi-Purpose Epoxy Repair Adhesive. RA 88 acts as the capping paste, sealing the crack face and securing injection ports, creating the necessary containment for RA 142 to be pressure-injected into the crack. This sequence ensures the super low viscosity RA 142 effectively penetrates and fills the entire crack network for a comprehensive structural repair.

Choose this when

  • When structurally repairing dormant hairline to fine concrete cracks (0.05mm to 3mm) in slabs, columns, or beams.
  • When high bond strength is required to restore monolithic behaviour to concrete sections or to bond hardened concrete together.
  • When preparing concrete surfaces by filling minor cracks and spalls prior to applying waterproofing membranes or other flooring systems.
  • When making high-strength spall repairs by mixing the epoxy with a suitable aggregate.

Don't use this when

  • Not for: Cracks wider than 3mm; consider ARDEX RA 144 for medium cracks.
  • Not for: Cracks subject to movement; this is a rigid, structural repair, not a flexible sealant for active joints.
  • Not for: Applications below 10°C or above 35°C, as this affects cure rates and product performance.
  • Not for: Stopping seeping or flowing water; cracks must be dry for best results, or water flow must be stopped prior to injection.
  • Not for: Thinning with solvents, which will prevent proper curing and compromise performance.

Understanding the Ardex Epoxy Repair Range

ARDEX RA 142 is specifically engineered for the structural injection of hairline to fine concrete cracks. For wider cracks (beyond 3mm), ARDEX RA 144 provides a suitable solution with a slightly higher viscosity designed to fill larger voids effectively. When performing vertical crack injection, ARDEX RA 142 is designed to be paired with Ardex RA 88 Plus Multi-Purpose Epoxy Repair Adhesive, which functions as a high-strength capping paste. RA 88 creates the essential seal and secures the injection ports, allowing RA 142 to be precisely injected into the crack network and achieve its full structural repair potential.