SpecChem > Products > Repair Mortars > Duo Patch

Duo Patch Green Conscious Product

Two-component polymer-modified concrete repair mortar with corrosion inhibitor

Duo Patch is a two-component, polymer-modified concrete repair mortar, enriched with an integral corrosion inhibitor. It’s designed for a variety of applications including horizontal, form and pour, and vertical and overhead when mixed to a stiffer consistency. Duo Patch is particularly effective in industrial settings such as warehouses, parking decks, and roadways, offering superior durability under heavy loads and abrasion.

  • Integrates corrosion inhibitor for added durability.
  • Suitable for repairs ranging from feather edge to 2 inches.
  • Can be used for interior and exterior overlay applications.
  • Provides excellent durability, adhesion, and freeze-thaw resistance.
  • Features an easy-to-trowel high slump consistency.
  • Cures to a natural concrete gray color, blending seamlessly with existing structures.

Tech Sheet
Safety Sheet
Spanish Tech Sheet


Surface Preparation: Ensure the concrete surface is solid, clean, and free from all contaminants, such as oil, grease, dust, and loose particles. To enhance durability, consider saw-cutting the perimeter of the repair area to be slightly deeper than the repair depth, creating a reinforced edge. The surface should be roughened up to a minimum Concrete Surface Profile (CSP) of 5, following the ICRI 310.2 Guideline, and kept in a saturated-surface-damp (SSD) state with no standing water.

Priming/Scrub Coat: Clean all exposed steel reinforcement of rust and apply SpecPrep SB for rust protection. The concrete surface should be SSD and primed with SpecPrep SB, applied via spray or brush. The repair mortar should be applied while the primer is still tacky or within its open time (refer to SpecPrep SB technical data sheet for specifics). Alternatively, a scrub coat of the repair mortar can be applied to the damp surface, followed immediately by the repair mortar before the bond coat dries.

Mixing Instructions

Mix 7.0 to 7.5 pints of DUO PATCH Admix with a 50-pound bag of DUO PATCH material using a low-speed drill to achieve the desired consistency. Start by adding the DUO PATCH Admix to the mixing container, then gradually incorporate the DUO PATCH powder, mixing for 2-3 minutes. Mix only what can be used within the pot life. For applications over 1/2″ thick, do not exceed 7 pints of DUO ADMIX. DUO PATCH can be applied from a feather edge up to 1″ in one layer for light traffic areas.

For deeper repairs over 1″, extend DUO PATCH with clean, SSD, 3/8″ pea stone up to 60% by weight (30lbs), mixing for an additional 2 minutes. This increases yield and should be used within 15-20 minutes of mixing.


DUO PATCH is available in two packaging options:

  • A 50 lb bag with a 1-gallon jug of DUO PATCH Admix.
  • A 60 lb pail unit, containing a 50 lb bag of DUO PATCH and a 1-gallon jug of DUO PATCH Admix.

Shelf Life

Unopened bags of DUO PATCH have a shelf life of 12 months when stored in a dry area. Store in a cool, dry location away from direct sunlight to maximize shelf life. Ensure the DUO PATCH Admix does not freeze.

Test Data

  • Set Time at 70°F (according to ASTM C266): The initial set time is approximately 40 minutes, with a final set time around 50 minutes.
  • Compressive Strength (as per ASTM C109):
    • At 1 day, the compressive strength reaches 2,500 psi.
    • At 7 days, it increases to 4,000 psi.
    • By 28 days, the strength peaks at 6,000 psi.
  • Bond Strength (following ASTM C882 modified): After 7 days, the bond strength is measured at 1,800 psi.
  • Length Change (based on ASTM C157):
    • Wet Cure at 28 days shows a slight expansion of +0.04%.
    • Air Cure at 28 days indicates a minor contraction of -0.02%.
  • Flexural Strength (according to ASTM C348):
    • At 7 days, the flexural strength is 650 psi.
    • At 28 days, it rises to 1,300 psi.
  • Yield: Each bag yields approximately 0.42 cubic feet.


Clean tools and equipment with water before the DUO PATCH hardens. Following these steps ensures a smooth application process and extends the life of your tools.