Lanxess inorganic iron-oxide Bayferrox pigments transform concrete for various applications, which include the colouring of various materials and also technical colour applications.
Chryso Southern Africa is the exclusive distributor of Lanxess inorganic iron-oxide Bayferrox pigments for the Southern African construction industry.
According to Hannes Engelbrecht, business manager of concrete aesthetics at Chryso SA, there are seven important factors that influence the quality of coloured concrete.
Factors to keep in mind when producing pigmented concrete:
• Cement: Portland cement can vary significantly in colour. “That is why it is important to use the same cement throughout the production of coloured concrete. White cement should be used when producing pigmented concrete with great colour clarity, particularly for bright colours. The higher the cement content, the more intense the colour,” says Engelbrecht.
• Efflorescence: “This is the result of free lime which is formed when the cement sets that, dissolved in the mixing water or in external water such as rain or dew, migrates through capillaries in the concrete matrix to the surface. There it reacts with carbon dioxide in the air to form insoluble and unsightly calcium carbonate deposits, which are particularly noticeable on the surface of pigmented concrete,” says Engelbrecht.
• Aggregates: The colour of aggregates also influences the ultimate colour. Therefore it is important to ensure that the entire surface area of the aggregate is coated with the pigmented cement paste to ensure that the final product is not a mixture of the colour of the pigment and the colour of the aggregate.
• Mixing water: Water dilutes the colour of the pigments in the mix and excess water evaporates from concrete, leaving behind pores that scatter incidental light and lighten the colour of the pigment.
• Formwork: The type, colour and condition of formwork can influence the surface colour.
• Dispersion: It is important to mix the pigment with the aggregate before the cement is added.
• Temperature during drying: In higher temperatures, fine crystals develop in the cement matrix. These crystals determine how the light that falls on the concrete is scattered. The smaller the crystals, the lighter the pigment in the concrete.
Bayferrox pigments are UV-stable and comply with quality standards EN 878 and ASTM C979. The pigments also carry the CE mark, which is a mandatory conformity marking for products sold in the European Economic Area (EEA).
Chryso SA’s colour laboratory in Jet Park houses sophisticated equipment such as a Colourimeter that can measure the colour strength of pigmentation. The laboratory provides customers with specifications to colour-match available concrete masonry production lines at competitive rates.
Tel: (011) 395 9700