Coloured concrete has a range of applications – whether used subtly to blend with nature or boldly to make a dramatic design statement.
Concrete can assume nearly any shape, design, pattern or texture. But the one characteristic that most distinguishes decorative concrete is colour, whether used subtly to blend with nature or boldly to make a dramatic design statement.
According to Architectural Concrete: a guide to achieving high-quality finishes by Daniel van der Merwe, there are many ways to create coloured off-shutter concrete finishes. These include:
• Using white cement.
• Adding a colour pigment to the concrete.
• Applying a coating to the form face that becomes an integral part of the surface finish.
• Applying a surface stain or coating after the concrete has cured.
• Coloured aggregates can also be used if the surface is tooled to expose the aggregates.
According to Van der Merwe, hardened concrete’s colour depends on the colours of the fine particles (cement, sand and pigments) that are used in the mix. Sand colour can influence concrete’s pigment significantly. Therefore it is important to carefully consider the colour of the sand used in coloured concrete work. It is particularly important in the case of light-coloured concrete – this includes colours such as yellow and blue.
Colour uniformity plays an important role in the aesthetics of off-shutter concrete. Slight colour variations in cement from different factories may occur due to the differences in raw materials. Therefore one should rather source cement from the same factory when colour plays a key role. However, colour variations on off-shutter concrete’s surfaces are not only due to changes in the colour of the sand or cement.