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Concrete Requirements for Polished Concrete
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NSW: 02 4314 1911      TAS: 0417 362 787
CAIRNS: 0427 151 275  QLD - 0429 151 275

 

 For every type of polished concrete there are subtle differences on what is required to achieve a polished finish. Please read our Buyers Guide to Polished Concrete here for some other factors to consider.

The main three finishes where this is important is for a cream polish (aka burnished concrete), partial aggregate exposure (aka hit n miss or salt n pepper) or full aggregate exposure.

Cream Polish or Burnished Concrete

The following special requirements apply for concrete surfaces;

CASTING

For the floor to have a uniform appearance, the casting is of the greatest importance. (A poorly cast floor will be costly to grind, and even if the function of a polished floor can be achieved, the finish will be affected by uneven aggregate, cracks, etc.) The appearance of the  finish is totally dependent on the concrete's appearance. Colour differences in the surface are to be expected. It is important to protect the slab during the building process from spills and staining as these cannot be removed.

  1. The surface should be power floated. (To achieve a surface as pore-free and level as possible, thorough power floating is required).
  2. The surface should be heavily troweled to obtain as smooth, dense and hard a surface as possible.
  3. Normally, the concrete surface should be water hardened under plastic sheeting for 5-7 days after casting, before it is time to start grinding.
  4. The surface must not be waterlogged when impregnating. (This is to enable the sodium silicate impregnation to
    penetrate and react with the concrete.)

Important Note:

You cannot change the colour of the slab. The higher the finish of polish the lighter the slab will be in colour, however:

  • hydration marks
  • cold joints
  • most chatter marks
  • footprints and consequent low spots left by them;
  • blowout holes from carpet smooth edge fixings.
  • any rough grainy finishes ESPECIALLY around the edges, internal corners and open doorways of slabs where the concreter’s helicopters cannot get to, and NO specialist care is taken to finish with hand tools to the same standard as the rest of the slab, CANNOT be rectified by polishing and will come out a completely different finish/colour to the rest of the slab.

 

Partial aggregate exposure aka Hit n Miss or Salt n Pepper

The following special requirements apply for concrete surfaces;

CASTING

For the floor to have a uniform appearance, the casting is of the greatest importance. (A poorly cast floor will be costly to grind, and even if the function of a polished floor can be achieved, the finish will be affected by uneven aggregate, cracks, etc.) 

  1. The surface should be power floated. (To achieve a surface as pore-free and level as possible, thorough power floating is required).
  2. The surface should be power troweled.
  3. Normally, the concrete surface should be water hardened under plastic sheeting for 5-7 days after casting, before it is time to start grinding. Grinding and honing can be carried out at this time while polishing is left until a later date, when the moisture level in the concrete is lower.
  4. The surface must not be waterlogged when impregnating. (This is to enable the sodium silicate impregnation to
    penetrate and react with the concrete.)

Important Note:

The more the concrete surface is worked the further down the aggregate will be pushed. It is important that the floor is level as this will affect the amount of stone that is exposed. A very poorly leveled floor will require significant grinding which will ultimately expose a high level of aggregate.

Full aggregate exposure

The following special requirements apply for concrete surfaces;

CASTING

For the floor to have a uniform appearance, the casting is of the greatest importance. (A poorly cast floor will be costly to grind, and even if the function of a polished floor can be achieved, the finish will be affected by uneven aggregate, cracks, etc.) It is important that special care is taken to minimise contamination of the concrete such as dirt/building products being walked in or cigarette butts. All boot holes must be filled with fresh concrete and not just filled in with slurry as this will leave footprints in the surface which cannot be ground out. The screed should also never rest or be excessively pushed into the surface as this will also cause the aggregate to be pushed down and this cannot be fixed later. 

  1. The surface should be power floated. (To achieve a surface as pore-free and level as possible, thorough power floating is required).
  2. The surface should be power troweled moderately. A hard troweled surface is more difficult and time-consuming to grind through.
  3. Normally, the concrete surface should be water hardened under plastic sheeting for 5-7 days after casting, before it is time to start grinding. Coarse grinding and honing can be carried out at this time while polishing is left until a later date, when the moisture level in the concrete is lower.
  4. The surface must not be waterlogged when impregnating. (This is to enable the sodium silicate impregnation to
    penetrate and react with the concrete.)

Important Note:

The more the concrete surface is worked the further down the aggregate will be pushed. It is important that the floor is level as this will affect the amount of stone that is exposed. A very poorly leveled floor will require significant grinding which still may not evenly expose the aggregate and remove boot prints and tiger marks in the concrete. 

  Before any new polished concrete slab is cast we always invite the builder or concretor to contact us and discuss the requirements specific to that application