In the production of directly demoulded concrete goods, quality is decided in seconds. From discharge into the mould to final compaction, everything has to go right: fast, even mould filling, consistent density across the board, and enough green stability to survive immediate demoulding without deformation. Filling aid admixtures are designed specifically for this critical window. 

How do filling aids work?

Their core job is to improve how stiff concrete behaves during mould charging and compaction. Semi-dry concrete is always a balancing act: it needs enough cohesion to hold its shape, but not so much internal friction or stickiness that it resists flowing into edges, corners and fine mould details. Filling aids shift this balance in the right direction, through better wetting and distribution of fine particles, reduced adhesion to machine surfaces, and more even movement of the mix under vibration and pressing. The result is more consistent behaviour during production, without losing the green stability needed for immediate demoulding. 

Mix design optimisation and standard compaction aids can both reduce stickiness and improve mould filling. A dedicated filling aid goes further, achieving the best stickiness reduction while also supporting compaction at a level close to a standard compaction aid. 

Production benefits from filling aids

In practice, this means fewer typical production problems: underfilled edges, density differences across the production board, visible compaction pores and uneven surface texture. Lower porosity and more uniform compaction improve strength, reduce water uptake and support long-term durability. More stable production also means fewer rejects and less waste, so filling aids matter for process efficiency just as much as product quality. 

Influencing factors

• moisture content and its even distribution across each batch
• aggregate grading and fines content, which control particle packing and internal friction
• cement type and binder fineness, which affect how the admixture interacts with the paste
• temperature and plant conditions, which influence stiffening rate and working time
• machine settings, vibration energy and pressing force, which determine how well the admixture's potential converts into real compaction

Application and products

Key benefits include:

• consistent density across the production board
• reduced waste and rejects
• better compaction
• smoother surfaces
• higher and more reliable mechanical properties, all in a chloride- and alkali-free formula