ARDEX A 828 Filling Compound & Smoothing Plaster
Fast-setting, crack-free plaster for filling, smoothing, and finishing interior walls and ceilings.
ARDEX A 828 is a brilliant white, rapid-hardening gypsum-based plaster designed for filling, smoothing, and finishing interior wall and ceiling surfaces. It’s ideal for use over a wide range of substrates, including concrete, render, plasterboard, aerated concrete, and even sound decorative coatings such as Artex. With excellent slump-free and non-shrink properties, ARDEX A 828 creates a smooth, durable surface that can be painted or wallpapered in as little as one hour.
Key Features & Benefits
- ✅ Fast drying – ready to paint in as little as 1–2 hours
- ✅ Versatile application – ideal for filling, levelling, and skimming walls and ceilings
- ✅ Covers old decorative finishes such as Artex and textured coatings
- ✅ Slump-free, tension-free, and crack-free formula for easy application
- ✅ Can be applied up to 30 mm thick in one coat
- ✅ Non-shrinking and suitable for deep wall repairs
- ✅ Lemon-scented version available for sensitive environments
- ✅ Ideal for smoothing and plastering render, concrete, plasterboard, aerated concrete, and construction boards
Ideal Applications
ARDEX A 828 is perfect for a wide range of interior wall and ceiling finishing tasks, including:
- Filling large surface depressions, cracks, and deep holes
- Repairing and levelling uneven walls and ceilings
- Covering old, sound decorative finishes such as Artex
- Dot-and-dab plasterboard installation
- Fixing electrical chases and dowelling wall plugs (non-structural)
- Smoothing concrete, render, or construction boards prior to decoration
- Filling and jointing gypsum plasterboards or prefabricated concrete slabs
Surface Preparation
Surfaces must be dry, rigid, clean, and free from dust, grease, or contaminants. Most absorbent backgrounds (such as gypsum or cement-based plasters) can receive ARDEX A 828 directly. For smooth or dense surfaces, priming is recommended:
- ARDEX P 51 (diluted 1 : 3 with water) for dense or smooth concrete
- ARDEX P 82 or ARDEX P 4 for non-absorbent or painted surfaces
Always perform a trial application on unfamiliar substrates.
Mixing Instructions
Gradually add 2 parts powder to 1 part clean water (approx. 13 L water per 25 kg bag) while stirring continuously. Use a drill with a spiral paddle for best results. Allow to stand for 2–3 minutes, then remix to a creamy, lump-free consistency. Working time at 20 °C is approx. 30 minutes.
Application
Apply ARDEX A 828 with a trowel, blade, or filling knife. Thanks to its slump-free formulation, the plaster stays in place even on ceilings and vertical surfaces. For best results:
- Fill holes gradually from the edges to prevent air entrapment
- Finish with a damp sponge or smoothing blade for a perfect surface—no sanding required
- Apply subsequent coats once the previous layer has hardened, if necessary
Apply only at temperatures above 5 °C.
Thickness & Drying Times
- Application thickness: Feather edge up to 30 mm
- Drying time (20 °C): 1–2 hours for 1–2 mm / 5–6 hours for 10 mm
Once dry, the surface can be painted or wallpapered directly.
Coverage
- Approx. 25 m² @ 1 mm thickness
- Approx. 8.5 m² @ 3 mm thickness
Technical Data
| Mixing Ratio | Approx. 13 L water : 25 kg powder (1 vol. water : 2 vol. powder) |
| Working Time (20 °C) | Approx. 30 minutes |
| Bulk Density | Approx. 1.0 kg/L |
| Mortar Weight (Freshly Mixed) | Approx. 1.5 kg/L |
| Material Requirement | Approx. 1.0 kg powder per m² per mm |
| Paint/Wallpaper Application | After surface is dry (typically 1–2 hours) |
| Ball Pressure Hardness (28 days) | Approx. 9 N/mm² |
| Tensile Bending Strength (28 days) | Approx. 4 N/mm² |
| pH Value | Approx. 8 |
| Embodied Carbon (A1–A3) | 0.49 kg CO₂ eq/kg |
Packaging & Storage
Supplied in 25 kg and 5 kg paper sacks with polyethylene lining. Store in original, unopened packaging, off the ground in cool, dry conditions, and protected from extreme temperatures. Shelf life: 12 months. Reseal part-used bags tightly.
Frequently Asked Questions
What is ARDEX A 828 used for?
ARDEX A 828 is a versatile filling and finishing plaster for interior walls and ceilings. It’s ideal for levelling, smoothing, and repairing uneven surfaces before painting or wallpapering.
Can ARDEX A 828 be applied over Artex?
Yes. ARDEX A 828 can be used directly over sound Artex and other decorative finishes to achieve a smooth, modern surface.
How long does ARDEX A 828 take to dry?
At 20 °C, thin layers (1–2 mm) can be painted after about 1 hour, while thicker layers (10 mm) dry within 5–6 hours.
Do I need to prime before applying ARDEX A 828?
Most absorbent surfaces do not need priming. However, smooth or non-absorbent surfaces should be primed using ARDEX P 51, P 82, or P 4 depending on substrate type.
What thickness can ARDEX A 828 be applied at?
It can be applied from a feather edge up to 30 mm in one coat without slumping or cracking.
Is ARDEX A 828 suitable for deep wall repairs?
Yes. Its fast-setting, non-shrink formulation makes it ideal for filling large holes, static cracks, and chases.
Can I sand ARDEX A 828?
Usually not required, as it can be sponge-finished. However, it can be sanded lightly once fully hardened if a finer surface is desired.
