Our priority is for you to be entirely satisfied with the outcome of your project, and so it’s important that you understand the inherent qualities of the materials you may choose – in this case, concrete. This will ensure you are well pleased with the results from this excellent landscaping material.
Please read the following points before proceeding with any concrete job (especially coloured concrete, exposed aggregate, honed concrete, stamped concrete or faux brick).
A number of variables mean that no two concrete slabs are identical:
Concrete is made from natural raw materials
Weather, water and site conditions
Placing and curing methods
Concrete slabs will exhibit uneven shading of aggregates or oxide, giving a look which is sometimes referred to as ‘mottled or ‘aged. An entirely consistent hue or shade (such as that seen in tiles or carpet) cannot be guaranteed with concrete, even though a damp proof membrane (e.g. polythene) over the sub-base may reduce the incidence of mottling (more noticeably so on coloured slabs) by providing a consistently dry sub-base and therefore more even curing.
The inconsistency of shade may mean that two pours of the same mix appear different.
Comparing variances in shade on a decorative slab is similar to comparing full, half or even quarter tints of paint.
Sample discs on coloured concrete sample boards are small and have been cast and not poured like floor slabs – therefore the uneven colouration effect mentioned may not be visible in the samples. All samples, photographs and brochures should be used as an indication only, not a direct comparison.
All concrete slabs may crack, no matter how they are prepared and poured. Although there are several procedures we use to lessen the likelihood of cracking, crack free slabs cannot be guaranteed. Green Gables follows trade best practices when preparing sites and placing concrete (Cement and Concrete Association of New Zealand information bulletin 1B 33: Specification and Production of Concrete Surface Finished). Reasons beyond our control which may contribute to concrete cracking include inadequate curing due to adverse weather conditions; inconsistent concrete mixture from the concrete supplier; or pre-existing and unforeseen site conditions leading to instability.
Trowel marks and screed marks may be visible.
The appearance of a concrete slab will change significantly if it is acid washed.
A concrete slab spanning from an internal area to an external area will look different inside versus outside due to the differing light.
Because concrete is made from natural raw materials, these points are properly seen (from an aesthetic perspective) as characteristics rather than faults.
The above information is pertinent regardless of concrete supply company, plant location, or contractor.
We advise you to read the Peter Fell All Colour System booklet entitled ‘General Information’, available online. We also advise you to read the ‘Decorative Concrete Guidelines’ brochure by the New Zealand Ready Mixed Concrete Association, available from Firth.
We strongly advise that if you are not satisfied with any of the points above you should not proceed with concrete for your project.