Concrete as an architectural product was not very well known in past. Often it was considered as structural material without little or no room for using it for decorative purpose. The link given below provides basic information on using concrete as architectural material.

The products covered are as follows

Colored Concretes
Cementitious Floor Screeds
Methods for Adding Colors to Concrete
Natural Pigments
Synthetic Pigments
Permanent Coloring
Stains on Concrete
Efflorescence
Composition of Efflorescence and its Evolution
The Effect of Efflorescence
Reducing the Effects of Efflorescence
Screen-Printed or Photo-Engraved Concrete

Architectural Concrete - Colored and Decorative Concretes and Concrete Staining