It's not something that architects often encounter. Concrete is an artificial stone which is made by mixing cementitious materials, water and coarse and fine aggregates in a proper proportion and hardening after a certain period of time.
Ordinary concrete (concrete for short) is composed of cement, sand, stone and water, and an appropriate amount of additives and admixtures are often added. In concrete, sand plays a skeleton role and is called aggregate; Cement and water form cement slurry, which is wrapped on the surface of aggregate and fills its gaps. Cement slurry plays a lubricating role before hardening, which makes the mixture have certain workability and is convenient for construction. After the cement slurry hardens, the aggregate is cemented into a solid whole.
Reinforced concrete (RC for short) is concrete mixed by cement, granular materials and water. After a period of maintenance, some tensile steel bars are added to achieve the strength required by architectural design. It should be one of the earliest composite materials developed and used by human beings.
Steel bar and concrete are two completely different building materials, with a large proportion of steel bar, which can bear both pressure and tension. However, it has high cost and poor heat insulation performance. The specific gravity of concrete is relatively small, and it can bear pressure, but it can't bear tension; Its price is cheaper, but it is not strong. The birth of reinforced concrete solved their defects and retained their original advantages, making reinforced concrete the first choice for modern building construction.
The history of concrete
Can be traced back to ancient times. The cementing materials used are clay, lime, gypsum and volcanic ash. Portland cement began to appear in the 1920s 19. Because of its good strength and durability, easily available raw materials, low cost, especially low energy consumption, it has been widely used.
186 1 reinforced concrete was applied for the first time, and dams, pipes and floors were built first. 1875, a French gardener (1828 ~ 1906) built the world's first reinforced concrete bridge.
At the beginning of the 20th century, someone published the theory of water-cement ratio, which laid the theoretical foundation of concrete strength. Later, lightweight aggregate concrete, aerated concrete and other concrete appeared one after another, and various concrete additives began to be used. Since the 1960s, water-reducing agents have been widely used, and high-efficiency water-reducing agents and corresponding fluid concrete have appeared. Polymer materials entered the field of concrete materials, and polymer concrete appeared; A variety of fibers are used to disperse reinforced fiber concrete. Modern testing technology is also increasingly applied to the research of concrete material science.
With the changes of the times and the progress of technology, new members have joined the "concrete family", in which fiber concrete has certain advantages in compressive strength and price. Although reinforced concrete is influenced by the competition of "concrete clan" and its development advantages are not as good as before, it can still be seen in many fields today. It is still synonymous with durability. High-rise buildings representing the image of the city naturally need reinforced concrete. Expressway, building bridges and tunnels are another aspect of the modern application of reinforced concrete. However, reinforced concrete also has a more practical function, that is, danger removal. When dealing with various collapse accidents, the use of reinforced concrete can make the key progress faster, because with its support, the rescue operation can achieve controllable results. Therefore, it can be seen from these aspects that reinforced concrete still occupies a place in many building materials, and we expect reinforced concrete to go better and more stable in the future construction road.