PHYSICAL PROPERTIES OF CONCRETE CONTAINING PIGMENTS.

The influence of iron oxide pigments on the development and intensity of color changes and the compressive strength and shrinkage properties of concrete are presented. The paper also describes the basis of color determination. Three pigments, namely, black, brown, and red, were added to concrete mixes ranging from 5 to 30 per cent by weight of the cement content. The work has shown that, while achieving a range of color for structural concrete, no deleterious effects on compressive strength or drying shrinkage of concrete were observed for pigment contents extending well beyond the presently accepted maximum value of 10 per cent.