Tips on how to prevent concrete discolouration

As precast concrete manufacturer you want a smooth concrete surface without discolouration. Differences in the colour of your concrete is not an attractive feature.

The uniformity of the concrete surface has vanished in thin air and you cannot use this concrete. To prevent concrete discolouration in the future, several measures can be taken. In this article you can read how to prevent discolouration on your concrete surface and how to increase the quality of your concrete.

Causes of discolouration of the concrete surface

To prevent stains on your concrete that affect the quality of the concrete, it is needed to find out where the change in colour comes from.

• The first cause of discolouration can be found in the use of materials in the concrete mix. Using different types of materials in your concrete batches can result in a change of colour in the finished product. In this situation, there is no consistency in materials;
• The second cause of discolouration of the concrete surface is the over addition of water during the production process. The addition of water in combination with inefficient mixing make discolouration visible in the concrete;
• Calcium Chloride can be used during the production process of concrete but is an important cause for differences in concrete colour. Calcium Chloride is used in some countries to speed up the initial setting time of the concrete but can have unfortunate consequences that harm your concrete quality;
• The application of too much release agent can leave unintentional stains on your concrete surface. Too much agent causes oil puddles, leaving staining on the surface of the concrete.

How to prevent concrete discolouration

We want to focus on helping you with problems, so we will give some tips to prevent the inconveniences that discolouration can give.

Tip #1:  Avoid the use of Calcium Chloride. This can be disastrous for your concrete surfaces and the primary cause for concrete discolouration;

Tip #2: Make sure you have high quality moulds as the absorption rate can cause discolouration in the concrete. It is advised to invest in moulds that have a low absorption rate;

Tip #3: Use consistent materials with the same colours to avoid the difference in colour in your concrete mix;

Tip #4: Make adjustments for moisture content in your aggregates, not just for yield but for water cement ratio as too much free water will cause discolouration;

Tip #5: Make sure the release agent for your mould is applied properly to avoid puddles and oil stains on the surface. This can be done by personnel with good workmanship and with a precise spray system that was built for the misting of the agent. 

More information on how to prevent concrete discolouration and how Ecoratio can help you with this problem can be found in our eBook about concrete quality. Other problems in the concrete industry that might have influence on your production process are also discussed.