SpecChem > Products > Repair Mortars > RepCon UW Mortar

RepCon UW Mortar

Fiber-reinforced underwater hand pack repair mortar

RepCon® UW Mortar is a single-component, polymer-modified, fiber-reinforced concrete repair mortar designed for underwater applications. This mortar is ideal for use in environments from 1/2” up to several inches deep, providing minimal washout and exceptional resistance to salt water, chlorides, and sulfates. Typical uses include underwater concrete tanks, dams, seawalls, piles, piers, and other marine or hydraulic structures.

  • Single-component formula, just add water.
  • Anti-washout technology enables easy hand placement.
  • Cohesive consistency ensures optimum adhesion.
  • Suitable for application up to several inches thick.
  • High early strength allows for quick turnaround in tidal zones.
  • Non-shrink properties ensure maximum durability.
  • Fiber-reinforced for additional strength.

Tech Sheet
Safety Sheet


Surface Preparation: Ensure the concrete is sound and clear of marine growth and other contaminants such as laitance. Achieve optimal results by saw-cutting the repair perimeter at least 1/2” deep and water blasting to a uniform depth with a high surface profile for bonding. The surface temperature must be between 45°F and 90°F.

Mixing: Mix 5.5-6.0 pints of clean water per 50-pound bag, depending on the desired consistency, using a heavy-duty low-speed drill. Add water to the container first, followed by the RepCon® UW Mortar powder. Mix for 3-4 minutes to a non-sag consistency. The mixture will seem dry initially but will become smooth after continuous mixing. Only mix what can be applied within about 10 minutes.

Placement: After mixing, place the mortar in a bucket and submerge to maximize work time. Firmly place the mortar into the prepared area to ensure thorough contact with the bonding surface.


  • Available in 50 lb bags or 50 lb plastic pails.

Shelf Life

  • Shelf life of unopened bags is 12 months when stored in a dry, cool area away from direct sunlight.


  • Coverage: Approximately 20 sq-ft at 1/4” thickness.

Test Data

  • Set Time at 70°F (ASTM C266): Initial Set: 10 min, Final Set: 20 min.
  • Compressive Strength (ASTM C109):
    • 1 hour: 3,050 psi
    • 3 hours: 4,100 psi
    • 1 day: 5,150 psi
    • 7 days: 10,200 psi
    • 28 days: 11,300 psi
  • Underwater Bond Strength (14 days, ASTM C882): 1,150 psi
  • Flexural Strength (28 days, ASTM C348): 1,200 psi
  • Coefficient of Thermal Expansion (ASTM C531): 4.1 x 10^-6 in/in/°F