While summer is welcomed by all, it does come with its issues. With varying temperatures throughout summer, from the exceptionally hot day to the cool nights this may cause cracking issues for any concrete laid in this period.
If laying concrete, and there is uncertainty, then the first step is to get in touch with your local Atlas Concrete rep –phone (09) 486-3333.
Humidity and intense sun can cause quicker water evaporation to concrete laid, and this in turn can create cracking and disappointment.
- A first and very necessary step in retaining the water in freshly mixed concrete is to thoroughly moisten the sub-grade, before placing the concrete.
- Avoid delay in placing the concrete. Have sufficient labour and equipment on hand to perform the placing quickly. You may wish to pour smaller areas.
- Don’t order or try to place more ready-mixed concrete than you can reasonably expect to finish and cover.
- Care should be exercised with vibrators, to avoid over- vibration.
- During a pour in very hot weather, try to shade the concrete from direct sunlight.
- Prevention of rapid moisture loss through the use of wet coverings until final finishing can be completed, or spray with an evaporation retardant.
- Have sufficient skilled labour and equipment on hand to finish the concrete.
- In cases of extreme hot weather it may be wise to start jobs in the afternoon to take advantage of lower temperatures in the evening.
- A gentle breeze on a hot, dry day cannot be ignored. The evaporation rate of moisture from freshly placed concrete will increase rapidly on a hot day. The use of a wind break cloth may be necessary.
- Start curing as soon as possible, using a method that will ensure moisture losses are minimised and protects the concrete from temperature extremes.
- The use of crack inducers or early placement of saw cuts must be considered.
- Discharge concrete from waiting trucks as soon as possible. Heat evolution from cement hydration and continuous agitation results in temperature rises in the concrete which can cause a rapid loss in workability.
For Further information – Contact your Atlas Representative