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CASTING MOULDS FOR PRECAST CONCRETE

moulds casting form formwork

SAVE MONEY BY CASTING YOUR OWN 
PRECAST CONCRETE PRODUCTS

If you are a long distance away from Vanstone's factory in Pretoria, South Africa, there is good news!

You can save the high cost of transporting heavy concrete goods by buying the moulds from Vanstone and casting it locally or on site.

Vanstone has over 50 years' experience in precast concrete and casting moulds. It has in-house facilities to manufacture moulds in steel, fibreglass, PU-rubber and even wood.

 

Steel Moulds for Figure 8A Kerbstones

 

Ready for painting

 

  ECONOMIC CONSIDERATIONS:

  • Concrete is heavy and transportation over a long distance is expensive.
  • The nearer the precast factory, the cheaper the product.
  • Repetition and the economies of scale are important factors.
  • Raw materials like cement and aggregates are often locally available.
  • A good quality mould is the first requirement for a good precast product.
  • Good knowledge of concrete is essential.

 

TECHNICAL ASPECTS

Steel Moulds

  • Strong and durable - Can last for years and more than 500 casts if well made and looked after.
  • Costly but very economical in the long run.

Fibre Glass Moulds

  • Can express virtually any shape or form, which steel and wood cannot do.
  • Medium durability - about 100 casts if looked after.
  • Expensive, especially if the master plug has to be developed as well.

Polyurethane Rubber

  • Can take up textures and sculpted forms.
  • Easy demoulding
  • Durable - similar to fibre glass
  • Because of unpredictable shrinkage during curing, it is not dimensionally accurate.
  • Most expensive, especially if the master plug and mould has to be developed.

Wood

  • Economical if only a few casts are required. It may last for 20 casts if well made and looked after.
  • Leaves a wood texture on cast concrete surfaces, which is not always desirable.
  • Good strong wooden moulds are bulky.

 

IMPORTANT MAINTENANCE TIPS

  1. Always use a suitable mould release oil to prevent adhesion between the cast concrete and the mould.
  2. After each cast the mould must be cleaned of all cement residue before oiling again for the next cast.
  3. Before storage, moulds must be cleaned thoroughly. Steel and wooden moulds must be oiled for protection during storage.
  4. Store moulds under cover. If not, steel will rust, fibre glass and rubber will be damaged by UV and wood will dry out and crack.
  5. Handle moulds carefully. Do not drop or hammer. A mould that needs heavy hammering to release the concrete is not well designed.
  6. If a poker vibrator is used, do not allow it to touch the mould on the inside. Intense friction causes heat and burning. Fibre glass moulds are especially vulnerable.