Coatings increase the performance of gCC

Uncoated calcium carbonate tends to absorb moisture e.g. from the air. This can lead to clumping (agglomeration), which makes processing in industrial processes more difficult. 

Calcium carbonate is often used as a filler in plastics and polymers. When hydrophobically coated, it disperses better in hydrophobic polymer matrices (such as polyethylene, polypropylene, etc.), which improves the homogeneity of the end product as well as the mechanical properties.

In powders as well as in extrusion and injection moulding processes, hydrophobic calcium carbonate improves the flow properties and thus the processability. The more even distribution of the filler improves the surface of the end product.

In the production of paints, coatings and sealants, the compatibility of the fillers with the hydrophobic binders is crucial. Coated calcium carbonate improves compatibility and prevents segregation.

In building materials, for example, the reactivity of calcium carbonate with water can be undesirable; this reactivity can be reduced by the hydrophobic coating. 
Uncoated calcium carbonate absorbs moisture in packaged dry-mix dry-mix mortars. A hydrophobic coating prevents premature water absorption and improves storage stability.
Screeds and levelling compounds must have uniform strength and durability. Uncoated calcium carbonate increases the moisture absorption of the material and prolongs the drying time, which can lead to uneven curing. The hydrophobic coating ensures that moisture absorption remains controlled and the material cures evenly.
For concrete, the hydrophobic coating of the calcium carbonate minimises water absorption to control hydration. This improves the long-term durability of the concrete and reduces cracking.

In plasterboard, uncoated calcium carbonate as a filler leads to moisture absorption, mould growth and weakening of the structure. Hydrophobically coated calcium carbonate reduces water absorption and increases the durability of the boards.
For exterior fibre cement boards, the hydrophobic coating of the filler helps to reduce water absorption and protect the boards from damage caused by freeze-thaw cycles and the effects of moisture.
For waterproofing materials and waterproof coatings, the fillers must not be water-reactive. Hydrophobic calcium carbonate prevents the penetration of water and contributes to waterproofing.
In insulating materials, hydrophobic calcium carbonate helps to extend the service life of the material. Uncoated calcium carbonate could cause moisture damage due to water absorption and binding.