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When a concrete surface shows minor defects, bug-holes, or an inconsistent finish, the goal is a rapid, smooth, and durable cosmetic repair. It needs to disappear under an architectural coating or stand alone as a uniform surface. The RLA Penapatch Fairing Coat Mortar achieves this. It provides a fine-textured, fast-setting compound for thin-layer repairs, delivering a consistent, ready-to-coat finish. The right product ensures the surface looks right, every time.
RLA Penapatch Fairing Coat Mortar was specifically formulated to address surface imperfections on concrete and masonry. It delivers a fine-textured, polymer-modified cementitious compound that repairs cosmetic defects and provides a smooth, uniform finish up to 5mm thick. Its design prioritises excellent adhesion and negligible shrinkage, preventing common issues like telegraphing imperfections through subsequent architectural coatings or finishes. This compound creates a durable layer that can either be over-coated or left exposed for a clean, architectural look.
This fairing coat mortar is engineered for precision and rapid results. Its ability to be applied up to 5mm in a single layer means precise feather-edging and thin-build repairs are achievable without slumping. A fast initial set time of 25 minutes at 20°C allows for quick turnaround, while reaching 4 MPa compressive strength in 1 day and 20 MPa in 28 days (tested to AS1012 & AS2073) ensures a durable repair that resists impact and wear. Crucially, drying shrinkage is less than 300 microstrain at 28 days (tested to AS 1012.13), minimising the risk of reflective cracking and maintaining a consistently smooth finish under coatings.
RLA Penapatch Fairing Coat Mortar is designed for straightforward application. Mix a 20kg bag with 5.9 – 6.0 litres of clean water using a drill mixer until a smooth, soft mortar consistency is achieved. Work within the 25-minute initial set time, applying the mortar by trowel to the required thickness, feather-edging where necessary. The product is workable between 5°C and 35°C; adjusting water temperature can help manage working time in extreme conditions. For highly porous surfaces, or to assist with curing in warm, windy conditions, RLA recommends using RLA Rendergrip A as a primer or curing agent to reduce flash drying and premature setting.
This fairing coat mortar is ideal for situations demanding a superior aesthetic finish on concrete and masonry surfaces:
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.
