CONCRETE CARE... some helpful hints & answers to your queries
At Lawrence Concrete, we understand that your driveway or concrete job is a major investment. We have listed our advice and recommendations below to best look after your new asset. Some time and effort in those first days and weeks will go a long way towards ensuring your concrete cures slowly with optimum results.
Concrete can take from days to weeks to months to cure, and is dependent upon environmental conditions, ie; concrete cures quickly in warmer weather and slower in cooler months. For an optimum result, we need the concrete to retain it's moisture for as long as possible and cure slowly to help prevent cracking. On new (green) concrete, unsightly patches are a good sign that the concrete is slowly curing.
As a general guide, you will need to:
- Keep off walking on the concrete for a minimum of three days
- Keep all vehicles off the concrete for as long as possible for best results, but for a minimum of seven days in normal weather, and double that in the cooler months
- Keep large vehicles, eg. Furniture trucks, moving trucks, and large freestanding pools off the driveway permanently.
- Keep the concrete continuously wet for as long as possible, ie. get out the sprinkler. But do make it continuous rather than wet/dry/wet. If your driveway dries out too quickly without retaining its moisture, be prepared that it may crack somewhere.
After your concrete has been laid and is no longer 'green', it will be cut in a timely manner by an expert concrete cutter who is well versed in where to place concrete cuts, how many, and how far apart. Cuts are made to allow for movement caused by temperature changes and drying shrinkage. In the event your concrete cracks - you want to be able to control where it will crack and how (e.g. in a straight line instead of randomly).
Preparing for concreting is a messy business, especially during our wet Waikato winters. Please note, reinstatement around concrete completion, digger tracks if applicable etc is the responsibility of the property owner. If you have any concerns in this regard, please discuss them with us prior to commencement.
If you have concerns that the concrete may be marked after it has been laid (but prior to it fully curing) ie. the house is empty, troublesome area, neighbourhood kids drawing in the concrete, etc, then you will need to personally arrange to oversee the job after we have left the site. Should the concrete be damaged in this way please let us know ASAP as we may be able to minimise the damage for you (however, there will be a minimum callout charge for this, thank you).
PINTO DISCOLOURATION... what is it?
Pinto is a relatively infrequent problem but one that leaves all parties in a project disappointed.
It is a phenomenon that occurs all over the country, and no one cause has been established despite investigations by most major industry players. It happens regardless of concrete company, location, season, cement, admixtures, aggregates, and importantly for us happens in jobs both with and without colour.
It is highly unlikely to be caused by the concrete supplied either as jobs supplied before or after jobs that result in pinto are always fine.
Because of this lack of common factors, it is generally accepted that it is likely to result from a combination of environmental factors at the site or the curing process.
But to blame the contractor is also unfair as if it was known what combination of factors caused Pinto, they would avoid thisDespite being a global issue there is very little information on potential causes.
Pinto typically has an appearance of puddles or a cloudy appearance suggesting it is related to moisture. There are many opinions and theories but for each of these we have heard, there is usually a case disproving it.
It's obviously extremely disappointing but the functionality of the concrete is unlikely to be compromised as Pinto should only be an appearance/aesthetic problem only.
As a contractor there are no solutions available to fix this problem once the concrete has turned pinto in appearance.
Oxide concrete or coloured concrete will fade over time and sometimes can dry discoloured in patches also known as the Pinto effect. Lawrence Concrete (2016) Ltd will supply a consistent coloured concrete finish to the best of our abilities, but will not be held responsible.
CRACKING in concrete
Concrete cracks may occur in your concrete for a variety of reasons.
Cracks, whilst laying concrete are almost inevitable because concrete, as like with most other building materials, concrete moves with changes in its moisture content. Specifically, it shrinks as it loses moisture.
Being a brittle material it is liable to crack as it shrinks unless appropriate measures are taken to prevent this, e.g. by the provision of control joints.
Shrinkage cracking, although common, is not the only form of cracking. Cracks may occur also due to settlement of the concrete, movement of the formwork before the laid concrete is able to sustain its own weight, or due to changes in the temperature of the concrete and the resulting thermal movement.
Appropriate measures will minimise, these forms of cracking. In all cases, control joints at appropriate intervals is the best way to control cracking.