Cement is the most widely used cementitious material for construction. For example, concrete commonly seen on construction sites is made of cement, sand, and stones mixed in a certain proportion.
The common cement we commonly use is Portland cement, also known as Portland cement. Its invention has a history of nearly 200 years.
In 1824, the British construction worker Asputin discovered that the limestone was pounded into fine powder, mixed with a certain amount of clay, mixed with water and evenly stirred into mud, then the mud was heated and dried, and then the dry materials were beaten. It is broken into blocks and put into a lime kiln for calcination until all the carbonic acid gas in the limestone evaporates. After cooling, crush it into fine powder. When using, add a small amount of water and mix it into a mortar of appropriate consistency, which can be used in various construction operations. ”
Because the color of the cement after hardening is very similar to the color of the stones in Portland, England, it is commonly known as “Portland cement”. Asputin also became a great inventor of cement. , won the British "Portland Cement" invention patent certificate.
However, Asputin did not fully grasp the exact firing temperature and correct raw material ratio of "Portland Cement" at that time. The quality of the cement produced by his factory was very unstable, and even caused some buildings to collapse due to cement quality problems.
In 1845, another British man, Johnson, discovered in an experiment that making cement was a problem. The temperature of the kiln must reach a temperature sufficient to burn a certain amount of glass body in the fired block into black-green color, and the proportion of raw materials must be correct and fixed so that the burned product cannot contain excessive lime. Only when these conditions are met can Ensure that the cement is not easy to crack after hardening. Johnson & Johnson's discovery solved the problem of unstable quality that Asputin could not solve. In 1909, Johnson & Johnson filed a complaint with the British government, saying that he was the real one. Asputin could not be called the inventor of "Portland Cement" because he did not make cement of stable quality. However, the British government did not agree with Johnson & Johnson's complaint. Decision upholding Asputin's patent rights for "Portland Cement"