Sikadur®-31 Epoxy Adhesive | High-Strength Structural Repair Mortar

Sikadur®-31 is a professional two-component epoxy-based adhesive and repair mortar developed with special fillers. It stands out with its solvent-free formulation, moisture tolerance, and thixotropic structure.

The product provides strong adhesion on various surfaces, including concrete, steel, stone, brick, and epoxy-based substrates. It can be safely used for both bonding and repair applications thanks to its versatile performance.

Due to its non-sag properties, Sikadur®-31 is a reliable epoxy solution for structural repair applications, including vertical and overhead repairs.

Key Features

• Solvent-free formulation with high moisture resistance
• Thixotropic structure prevents sagging even in overhead applications up to 10 mm thickness
• Provides excellent adhesion performance on concrete, steel, stone, epoxy, and polymer-based surfaces
• Functions as both an adhesive and a repair mortar in a single product
• Does not require a primer and cures without shrinkage
• Provides high chemical resistance and complete water impermeability
• Offers strong mechanical resistance against structural loads
• Easy to mix and practical to apply
• Density: approximately 1.65 kg/L (A+B, +20°C)

Mechanical Performance Values

Compressive strength:
Approximately 60–70 N/mm²

Flexural tensile strength:
Approximately 30–40 N/mm²

Tensile strength:
Approximately 15–20 N/mm²

Bond strength:

• Concrete: >4 N/mm² (failure in concrete)
• Steel: approximately 15 N/mm²

Surface Preparation

Proper surface preparation is essential to achieve maximum adhesion performance.

• Concrete and mortar surfaces must be at least 28 days old.
• The surface must be sound, dry, clean, and open-textured.
• Oil, grease, cement laitance, paint, and existing coatings must be completely removed.
• Steel surfaces should be cleaned by vacuum after sandblasting.
• Moisture levels and dew point conditions must be checked. The surface temperature should be at least +3°C above the dew point.
• For polyester and epoxy surfaces, wet-on-wet application with a suitable primer is recommended.

Application Steps

• Components A and B are mixed until a uniform grey color is achieved.
• The mixture is transferred into a clean container and mixed again for approximately 1 minute.
• As an adhesive, it can be applied using a spatula, trowel, or notched trowel.
• For repair mortar applications, the use of formwork is recommended.
• On metal profiles, it can be applied up to 5 mm thickness and should be supported for at least 12 hours.
• After curing, adhesion can be checked by applying light hammer impact on the surface.

Recommended Application Areas

Sikadur®-31 is suitable for:

• Professional applications requiring high structural strength
• Bonding solutions where strong adhesion is required on difficult surfaces
• Technical repair solutions requiring waterproof repair mortar
• Bonding applications exposed to positive and negative loads
• Overhead structural repair works

Frequently Asked Questions (FAQ)

Does Sikadur®-31 sag in overhead applications?

No. Thanks to its thixotropic structure, it does not sag in applications up to 10 mm thickness.

What is the bond strength on concrete?

It provides adhesion strength of more than 4 N/mm², with failure occurring in the concrete substrate.

Is Sikadur®-31 waterproof?

Yes. It provides complete resistance against water vapor and liquid water.

How is its chemical resistance?

Thanks to its epoxy-based formulation, it provides high resistance against various chemical effects.

Is a primer required before application?

No. Sikadur®-31 does not require a primer for application.