A ‘must read’ for anyone pouring concrete this summer!
Temperature, humidity and wind speed all play a huge role in the rate of water evaporation from a freshly poured concrete slab.
Too much evaporation can lead to the following problems with the concrete:
Faster setting time
Reduced compressive strength
Surface flaking & colour differences
Our supplier, Boral Concrete, provides concrete according to the Australian Standard (AS 1379), but a lot of problems are occurring because site personnel are not aware of the problems with pouring in hot weather or how to handle them.
Below are a few tips that could save you some very big headaches.
Try to pour during cooler parts of the day
Use sunshades & windbreaks
Keep anything that touches the concrete cooled (use water or shade)
Consider applying an aliphatic alcohol to the surface once poured and screeded, to reduce the rate of evaporation and thus reduce the chance of cracking
Consider the concrete mix:
Plasticers can reduce water content (less water = less evaporation)
Retarders can allow extra time to finish (delays setting time)
Use the largest aggregate possible (keeps the concrete cooler)
Use the minimum cement content required (less cement = smaller impact from heat)
Check out the document provided by the Australian Pre-Mixed Concrete Association for more details and explanations of the above tips.
Protecting your Concrete
Smart App to Help Concrete Placement
As we hurtle towards Christmas, please take a moment to read this short message around hot weather.
With the warmer weather approaching it is important to keep in mind that concrete needs protecting to minimise the likelihood of plastic shrinkage and plastic settlement cracking. The CCAA (Cement Concrete Association Australia) provide guidelines:
The CCAA has developed a FREE APP which monitors local weather and provides a rating. The app can be downloaded from the iTunes and Google Play stores on your smart phone by searching for Smart Concreting or CCAA.