The history of concrete
This material was already used in the past by the Romans and Egyptians. Roman architecture is marked by the album caementicium which is considered the ancestor of the latterIt consists of mortar and stone varieties. It has always been popular because it is solid and easy to use. It was combined with other materials such as brick and it has achieved great constructions that are specific to the Romans.
In 1956, John Smeaton discovered that limestone guarantee of connector comes from limestone and clay. Thus, the concrete began to experience a better reputation from the 19th centuryIn 1812, Louis Vicat, France was able to determine the characteristics of different cements based on their relative limestone / clay. Then, several scientists were keen to learn more about this material. Thus was born 1824 in Portland Cement.
Over the years, the industrial production of cement has grown considerably and has achieved many buildings. The church of St Jean de Montmartre in Paris is one of the first constructions made from these materials.
The composition
Concrete is composed of sand and gravel which are agglomerated by a binder, the mixture is the mortar. A hydraulic binder is a cement making taken following hydration. The chemical reaction taking granting of this material is slow. You can make this process faster, and also slow it down by adding adjuvants. Plasticizers enhance the fluidity of it, its installation and its resistance.
The composition is obtained as a result of a complex arrangement. It is important to determine the quantity of each component to achieve the mechanical properties as well as the development complies.This is called making.
There are several techniques to develop this material, they can be complex but are rigorousIn a study of the various constituents, requires experimental verificationIn addition to laboratory analysis must take into account real situations at the place where there will be construction.
In general, for a small yard, concrete is made up of 2 / 3 of large particles and 1 / 3 for those fine. This is 800 liters and 400 liters of gravel sand per m3 of concrete for 350 to 400 kg of cement.
The formulation must take into account the conditions attached to the NF EN 206-1. Of these, there is the environment where this material will be installed, the minimum amount of cement and the maximum moisture content allowed in the formula. |
