Two major factors to understand about concrete:
- Colour will be mottled and there will be variations within the slab.
- Concrete will crack.
Factors which may influence the appearance of the final colour and texture to all types of concrete:
These are intended as an indication of the final colour, not as a comparison.
Handling and placing of concrete, the ambient temperature and weather conditions, all have an effect on the final colour.
Concrete slabs will change colour as they dry and cure.
If poured in more than one pour there may be a difference in tones.
Different textures on the surface of the concrete will change the final colour.
If poured in more than one pour there may be a difference in textures.
The application of sealer will change the colour appearance.
Concrete cracks are almost inevitable. Concrete moves with changes in its moisture content; shrinking as it dries. Being brittle, it is liable to crack as it shrinks. Its low tensile capacity, which varies with age and the rate of application of strain, gives it an inherent potential to crack.
Crack control is an integral part of reinforcing concrete and construction. Primary reinforcement controls crack width but excessive amounts of reinforcing steel can also increase the risk of cracking. Reinforcement (mesh) does not eliminate or reduce shrinkage cracking but transforms a few cracks into many fine and micro-cracks.
We can try to control cracks but we can’t stop them. Sub-base compaction, wind speed, concrete and air temperatures, humidity, method of duration of curing, different finishes and the nature of the aggregate can all cause non-structural cracks, as can settlement and formwork movement.
The type of aggregate used in New Zealand means that concrete here shrinks more and so cracks more than in other countries.
If the concrete is cut too soon the stones may chip and pop out. This is determined by temperature.
Types and causes of cracking include:
- Plastic settlement
- Plastic shrinkage
- Early thermal contraction
- Long term drying shrinkage
- Corrosion of reinforcement
- Alkali aggregate reaction
- Formwork removed too soon
20MPa concrete is used on driveways, paths, patios etc. This is only suitable for vehicles up to 3 ton in weight. Please check with your insurance company should vehicles above this weight be required to use the concrete.
Crack filler bonds the concrete together however concrete cracks due to many different causes. There is no guarantee that concrete won’t crack.
Note: We can only quote for the cracks that are visible, once the surface is properly cleaned there may be further cracks to be repaired that have not been quoted for.
The overlay is only a make-up covering. If the concrete underneath cracks so will the covering.
Why the concrete cracked in the first place and what the concrete may do in the future must be taken into consideration.
On acceptance of the quote it is in Oasis Concrete & Paving Ltd’s belief that the client has checked that it meets their Insurance Companies specifications.