Processes

Cast stone is an extremely versatile material and offers the designer an outstanding flexibility when designing features and structural elements on projects in both traditional and modern styles. Our GreconUK range of products are manufactured throughout all three of the cast stone processes, all of which offer their individual benefits which should be taken into consideration when planning for your project. 

 

Semi-dry

The semi-dry process involves the use of a low water content or ‘earth-moist’ mix. A semi-dry mix is compacted into moulds and the finished product is released almost immediately. This approach enables many repetitive elements to be cast in considerable numbers, and quickly.

Their surface tends to have an open grainy texture, like sawn natural stone.  A quarried stone ‘tooled’ finish, such as striated or rock face, can be replicated by reproducing the finish in rubber or epoxy resin.   Semi-dry cast stone elements tend to be smaller, partly because of the physical difficulty of incorporating complex reinforcement.

Some units employ a through mix of the finished face material, others a backing and facing mix. An integral waterproofer ensures low water absorption and long term durability.

  • The products are a very close match in colour and texture to and is favoured by planning authorities as, an alternative to quarried natural stone.
  • The 28 day cube strength is in excess of 35 MPa.
  • It has a low porosity, with weathering characteristics of quarried natural stone.
  • This method of manufacture has size restrictions to traditional products, such as cills, heads, string courses, etc
  • The process of tamping-in the material makes complicated reinforcement difficult to place into the mould.
  • It can be cast as a through mix or with facing and backing mixes.
  • It has a durability similar to quarried natural stone, with sharp arrises requiring careful on-site handling.
  • The cost effective production processes combined with a shorter lead time are seen as the major benefit of semi dry cast stone. The method also offers the user and specifier a product which resembles and weathers as quarried natural stone at a lower cost.

 

Wet-cast

The wet-cast process is similar to casting in plaster but it results in a dense product, with a typical cube strength of 35-50 MPa. It allows very precise rendering of fine detail and a high quality, close-grained surface finish. Acid etching, grit blasting, hand or mechanical tooling, and polishing are typical finishing techniques.

Wet-cast generally only yields one cast per mould per day and requires the removal of a layer of cement laitance before a satisfactory stone like finish can be achieved, normally by chemical etching or mechanical methods.

  • The products are an extremely close match in colour and texture to quarried natural stone, with the additional benefit of optional secondary finishes.
  • The 28 day cube strength is in excess of 35 MPa.
  • The product has very low porosity and retains its supplied appearance longer.
  • The unit sizes available are only restricted by crane and transport limitations.
  • The product is cast as through mix.
  • Finished products are extremely durable in respect of impact damage, but still requiring careful on-site handling.

 

Fibre Reinforced Cast Stone (FRCS)

This dense product with a close face is often produced in slimline sections to reduce its weight. This not only improves manual handling but can enable retrofitting to a structure. Cast as a through mix, a higher water content mix design incorporating fibre reinforcement is poured or sprayed into moulds and released the following day. Secondary treatments can be used to vary texture.

  • Produces products which are a very close match in colour and texture to quarried natural stone, with the additional benefit of optional secondary finishes.
  • The 28 day cube strength is in excess of 35 MPa, yet offers enhanced tensile and bending strength due to the materials used during the process of production.
  • Unit sizes available are only restricted by mould manufacturing and fixing considerations.
  • Very low porosity. Retains supplied appearance longer.
  • The product includes fully integrated alkali resistant fibre reinforcing.
  • It is cast as through mix.
  • The products are very durable in respect of impact damage, but still requiring careful on-site handling. Units are normally produced as thin walled products with the reduction in weight assisting with site and manual handling considerations.
  • When manufactured as thin walled units, this method of production is particularly suited for retro fit and refurbishment projects. It can be used to give additional tensile strength when full sized units are produced, where the total weight of units is a design and construction consideration.

 

 

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