For thin-layer repairs over surface imperfections, RLA Penapatch Fairing Coat Mortar provides a smooth, fine-textured finish on concrete, masonry, and existing RLA mortars. Formulated with a blend of cement and polymers, this compound achieves rapid early strength with minimal shrinkage, producing a surface that does not telegraph or show through overlaid architectural coatings. It is suitable for both internal and external vertical applications, and can be left exposed as a stand-alone final coat or overcoated with protective finishes.
Penapatch Fairing Coat Mortar relies on a polymer-modified cementitious design to achieve excellent adhesion to mineral substrates without requiring a separate bonding agent under standard conditions. The fast-setting chemistry achieves a 20 MPa compressive strength at 28 days while maintaining a low drying shrinkage profile of less than 300 microstrain, preventing fine cracking across thin applications up to 5mm deep. When applied over other repair mortars, it fills surface blemishes, voids, and defects to create a uniform, paint-ready substrate.
Ensure the substrate is fully cured (new concrete must be cured at least 21 days), clean, and free of laitance or bond-inhibiting contaminants. Remove weak concrete and use scabbling or water blasting to establish a mechanical key. Pre-soak the surface with clean water, ensuring no free-standing water remains before application.
For highly porous surfaces, apply RLA Rendergrip A prior to pre-soaking to prevent the mortar from flash drying and to preserve workability. Mix the mortar using a forced action drill mixer and paddle, slowly adding the powder to 5.9 to 6.0 litres of water to prevent lumping. Apply by trowel to the desired thickness up to 5mm. Do not overwork the surface or re-temper partially set product. In warm conditions, high winds, or direct sun, apply RLA Rendergrip A as a curing compound immediately after the final trowel to prevent premature drying.
No, this product is specifically formulated for thin-layer repairs up to a maximum of 5mm per application. For deeper sections, use a suitable bulk repair mortar first, then apply the Fairing Coat Mortar for a smooth finish.
If the underlying substrate moves or cracks, the reflective cracking will transfer through the Fairing Coat Mortar. This product does not bridge active cracks; it requires a stable foundation.
Finishes can be applied after 48 hours when ambient temperatures are between 10°C and 35°C. If temperatures are below 10°C, allow an additional 24 hours of curing time before overcoating.
No, do not use RLA Penapatch Fairing Coat Mortar in areas subject to rising dampness or where it will be continuously wet. This limitation protects against bond failure and product degradation.
| Application | Key benefit | Primary trades |
|---|---|---|
| Infilling concrete surface imperfections | Achieves a smooth, uniform surface that will not reflect through architectural coatings. Fast setting provides a 25-minute working time, speeding project flow. | Concrete repairers, renderers, painters |
| Repairing concrete defects up to 5mm thick | Excellent bond strength to concrete and negligible shrinkage reduces callback risk. Durable repair for minor damage. | Patch repairers, general builders |
| Vertical concrete repairs | Excellent workability and controlled slump make overhead and vertical applications manageable, reducing material waste and improving finish quality. | Renderers, concrete patchers |
| Finishing over other RLA mortars | Creates a fine-textured, smooth surface, preparing rougher repairs for decorative coatings or exposure. | Concrete repairers, coating applicators |
| Exposed final coat on concrete | Can be left exposed as a final finish, offering a durable and light grey aesthetic without requiring further coatings. Compressive strength of 20 MPa at 28 days supports this. | Commercial builders, maintenance teams |
Mechanically remove laitance and weak material; clean thoroughly. Pre-dampen to SSD and ensure no standing water remains.
Scabbling, grinding, or high-pressure water-blasting to provide a consistent key.
Pre-soak, then allow surface to return to SSD prior to application.
Add powder to 5.9–6.0 L of clean water per 20 kg while mixing with a low/medium-speed paddle to a smooth, soft mortar.
Minimises lumps and ensures uniform consistency. Do not re-temper once set begins.
Use warm water in cool weather and chilled water in hot conditions to optimise working time.
Trowel apply to the required finish. Limit single-pass thickness to 5 mm; feather-edge as needed for patching.
Apply with firm pressure to ensure full contact; avoid over-working the surface.
Protect from premature drying. Use a compatible curing agent on exposed repairs and in warm or windy conditions. Coatings can generally be applied after ~48 hours at 10–35 °C; allow longer below 10 °C.
Danger: Causes serious eye damage. May cause an allergic skin reaction. May cause respiratory irritation. Causes skin irritation.
Wear protective gloves (neoprene rubber), protective clothing, safety glasses with side shields or chemical goggles, and face protection. Use a particulate respirator (P1, P2, or P3 depending on exposure) in dusty conditions. Remove and destroy contaminated leather items like shoes and belts.
Use only outdoors or in a well-ventilated area to avoid breathing dust or fumes. Prevent concentration in hollows and sumps.
Store in original, securely sealed containers in a cool, dry area at room temperature, away from cold floors and direct sunlight. Store locked up. Dispose of contents and container at an authorised hazardous or special waste collection point according to local regulations. Do not allow wash water to enter drains.
Proper surface preparation is critical for adhesion and longevity. Adhering to these guidelines prevents bond failure and ensures the repair holds.
Surface prep: Surfaces must be clean and free from oil, grease, paint, or any contaminants that might inhibit bond. Remove all cracked or weakened concrete to expose a solid base. Scabble or water blast the surface to remove laitance and create a mechanical key. New concrete surfaces must cure for at least 21 days before application.
Primer: Surfaces should be pre-soaked with fresh, clean water. Ensure no excess or freestanding water remains, as this will reduce bond strength. For highly porous surfaces, apply RLA Rendergrip A before pre-soaking to prevent flash drying and maintain workability.
| Property | Value |
|---|---|
| Colour | Light Grey |
| Wet Density | 1800 kg/m³ |
| Application Temperature | Min 5ºC - Max 35ºC |
| Water per 20kg bag | 5.9 – 6.0 litres |
| Yield per 20kg bag | 14 litres |
| Flexural Strength (1 day) | 3.0 MPa (ASTM C348-86 @ 20ºC) |
| Flexural Strength (7 days) | 5.0 MPa (ASTM C348-86 @ 20ºC) |
| Flexural Strength (28 days) | 7.1 MPa (ASTM C348-86 @ 20ºC) |
| Compressive Strength (1 day) | 4 MPa (AS1012 & AS2073 @ 20ºC & 50% RH) |
| Compressive Strength (7 days) | 18 MPa (AS1012 & AS2073 @ 20ºC & 50% RH) |
| Compressive Strength (28 days) | 20 MPa (AS1012 & AS2073 @ 20ºC & 50% RH) |
| Drying Shrinkage (7 Days) | <100 microstrain (AS 1012.13) |
| Drying Shrinkage (28 Days) | <300 microstrain (AS 1012.13) |
| Drying Shrinkage (56 Days) | <450 microstrain (AS 1012.13) |
| Setting Time (Initial) | 25 minutes (@ 20°C) |
| Setting Time (Final) | 50 minutes (@ 20°C) |
| Overcoat Window | 48 hours (10ºC – 35ºC) |
| Shelf Life | 12 months |
Here are some common examples on where RLA Penapatch Fairing Coat Mortar used by our customers.
