About Coloured Concrete
Concrete is a composite material composed mainly of water, aggregate, and cement. Additives and reinforcements can be included in the mixture to achieve the desired physical properties of the finished material. When these ingredients are mixed together, they have liquid like properties that enable it to be shaped into many forms prior to hardening into a rock like substance. This is all made possible by the dual nature of Portland cement. Fresh cement paste is a lubricant while hardened cement paste is an adhesive.
The first recorded use of concrete was in 3000BC by the Egyptians to build pyrimids. They mixed mud and straw to form bricks with gypsum and lime being used to make mortar.
The ancient Roman’s developed a material very close to modern concrete, using lime, volcanic ash with salt water. This was used to build their architectural marvels such as the Coliseum and the Pantheon which remain standing today.
The Portland cement used in concrete today was invented in 1824 with the use of oxides for colouring concrete occurring almost 100 years later. Decorative concrete was developed in the 1950s with concrete bench tops being manufactured in the 1980s and polished concrete floors in 1999.
Today Oxides are used in many industries from soap and crayon manufacturing to carpet and food colouring with the most common use being in coloured or decorative concrete for bench tops, polished floors, patio’s, pool surrounds, drives, footpaths and tiltslab construction.
Pigments are finely ground coloured particles that when blended into a concrete mixture, infuse the concrete with their shade.
Iron oxide pigments utilises iron scrap to produce oxides with inherent chemical stability and colour fastness making them ideal for use in concrete.
People have been using pigments since Palaeolithic times, when pulverised minerals and charcoal were employed in cave paintings that have retained their vivid colouration for as many as 30,000 years. Today’s pigments contain some of the same mineral oxides and carbon black compounds used historically, however synthesized pigments have substantially replaced pigments from naturally occurring pigment deposits. The new processes have resulted in pigments that have greater tinting strength and are more consistent and economical to use.