What causes light and dark patches in some concrete?
Discoloration is a lack of uniformity in the colour or tone of the concrete. There are a number of different types of discoloration with different causes. The most common type, known as ‘trowel burn’ results from placing and finishing concrete after the hydration has started and the concrete is beginning to set. For more information on this topic please refer to CIP 23 in the ‘Concrete in Practice’ series.
