This option is ideal for interior surfaces in contemporary style homes. To create the look, the concrete surface is ground to a smooth finish to expose the aggregate below. Coloured oxide and special aggregates can be incorporated into the mix, and feature aggregate can be broadcast into the surface if required.
Schnapper Rock Road
Concrete Laying Tips for Honed Finishes
- Do not use less than a 20MPa concrete. Higher strength concrete can allow the surface grinding process to be carried out at an earlier age.
- Do not have the concrete slump at a high level. In high slump concrete there is a tendency for aggregate segregation. 100 mm slump is sufficient.
- Care needs to be taken when the concrete is vibrated. Over vibration and vibrator dragging can cause vibrator trails and segregation that show in the polished surface after the concrete is ground.
- During laying, if the concrete is walked through do not screed cement paste back over the hole created. Take a hand full of concrete containing aggregate and paste, place this in the footprint. If this is not done then, after grinding there may be a paste only patch in the shape of a footprint.
- Consider the use of an evaporation retardant on dry, windy or hot days or in conditions of high evaporation.
- A U3 finish is recommended with the use of a power trowel.
- Cure the concrete for as long as possible, use a curing compound, ponding or wet the surface and cover with polythene trapping water between the polythene on the concrete.
- Normal good laying practice needs to be used to produce a quality finish. The fresh concrete should not be overworked. Always adhere to the relevant Standards NZS 3109 and NZS 3114.
- The first grind can be carried out 7 to 9 days after laying. Talk to the grinding contractor for confirmation of grinding dates and final grind fineness. The Standard for slip resistance is AS/NZS 3661.1.1993. Different grind mediums produce different slip resistance.
- After the first grind if there are bug holes in the surface, these can be filled with fresh paste to match the concrete before the final grind.
- Cut as soon as possible to prevent uncontrolled shrinkage cracking. Consider using early age entry cutting. Care is needed when planning structural and decorative cuts. Caution is needed where under floor heating is used.
- Seal the concrete to provide an easy to clean surface that will resist absorbing spilt liquids. Sealers can also affect slip resistance check with the sealer supplier.
NOTE: It is recommended that a pre-pour meeting is held with all concerned
to discuss expectations, roles, procedures and responsibilities.