Cements

Cement is a "hydraulic binder". By "binder", we mean a material capable of agglomerating other materials. The qualifier "hydraulic" specifies, on the one hand, that this binder hardens cold by mixing with water, without the addition of any other reactive body and, on the other hand, that it hardens not only in air, but also in water.

Note in passing that a pozzolanic binder needs activation to acquire this hydraulic character. The substance acting as the activator is most often lime (lime added or released by the setting reaction of a hydraulic binder). In other words, a pozzolanic binder activated with added lime is a hydraulic binder. But also, a pozzolanic binder, mixed with a hydraulic binder, becomes a hydraulic binder due to the lime released by the setting reaction of the hydraulic binder.

Mixed with certain soils or aggregates, and in the presence of water, cement progressively creates a growing cohesion within the mixture, resulting in rigid, hard materials with high mechanical performance, compatible with the desired requirements of a building material. Depending on the nature of the constituents used and their proportions in the mixes produced, the magic powder that is cement enables the development of a wide variety of products to meet the needs of designers, users and operators of structures in fields as diverse as building, engineering structures, civil engineering and roads. These include concrete (or rather concretes), the world's most widely used construction material, as well as all materials treated with hydraulic binders used in the construction of transport infrastructures (roads, pavements, earthworks, industrial or airport platforms, etc.).

At this point, two questions come naturally to the reader's mind: "What is cement made of?" and "How did man discover cement?"