Coloured Concrete with Focus on the Properties of Pigments

Abstract

In this paper the possibilities of colouring concrete and the use of pigments are presented. There are two groups of pigments with respect to its manufacture (organic and inorganic) and three different forms available on market: powder, granulates and slurry. Next to the influences of other concrete components the effects of fine pigment particles on the properties of fresh and hardened concrete are introduced. Because of the higher need of water the workability of each mixture is affected. With the increasing specific surface area of pigment the flow of fresh concrete decreases. On the other hand this characteristic feature causes slightly higher density of concrete matrix which results in better durability. Optimal dosages differs depending on the form of pigment, for powders it is about 5% of the weight of cement content. Higher amounts don ́t bring about higher tinting strength and in the case of more than 10 % its mechanical properties can be negatively affected. An example of colour evaluation as well as utilization of recycled materials as colouring agents are also mentioned.