Urgent steps are also required to promote alkali activated pozzolan or geopolymer cement based concretes. They were originally known under the names "soil silicate concretes" and "soil cements". Although highly fragrant, concretes contain large quantities of non-fragrant waxes and resins. Polymer concretes are mixtures of aggregate and any of various polymers and may be reinforced. Iron oxides are inexpensive and durable pigments in paints, coatings and colored concretes. Polymer concrete is generally more expensive than conventional concretes. Like all concretes comprising pozzolans, they are more durable than concretes made from Portland cement. Reactive powder concretes may also make use of silica fume as a fine aggregate. The first testing of silica fume in Portland-cement-based concretes was carried out in 1952. In reinforced concretes intact regions will sound solid whereas delaminated areas will sound hollow. Polymer concretes are frequently used for repair and construction of other applications, such as drains. Commercial reactive powder concretes are available in the strength range. Research into new fiber-reinforced concretes continues today. They have a number of "Honorary Concretes" who play on their records. The Concretes acted the role of the protagonist in the video.