Whose patent belongs to cement concrete?

Cement is the most widely used cementing material in construction, such as concrete commonly used in construction sites, which is made by mixing cement, sand and stone in a certain proportion.

This kind of ordinary cement that we often use is called portland cement. It has been invented for nearly 200 years.

1824, British construction worker asp Ding found that limestone was pounded into fine powder, mixed with a certain amount of clay, and stirred evenly with water to form slurry, then the slurry was heated and dried, then the dry material was crushed into pieces, and then it was put into a lime kiln for calcination until all the carbonic acid gas in limestone evaporated. After cooling, it is pulverized into fine powder, and when in use, a small amount of water is added and stirred into mortar with appropriate consistency, which can be applied to various construction occasions. "

Because the hardened color of this cement is very similar to the color of the stone in Portland, England, it is commonly known as "Portland cement". As a result, asp Ding became a great inventor of cement and obtained the patent certificate of "Portland cement" in Britain.

However, at that time, asp Ding did not fully grasp the accurate sintering temperature and the correct raw material ratio of portland cement, so the quality of cement produced by his factory was very unstable, and even some buildings collapsed because of cement quality problems.

1845, another Englishman, Johnson, found in an experiment that when making cement, the temperature of the kiln must be enough to burn a certain amount of glass body in clinker into dark green, the proportion of raw materials must be correct and fixed, and the burnt product must not contain excessive lime. Only when these conditions are met can cement not crack easily after hardening. Johnson & Johnson's discovery solved the problem of unstable quality that asp Ding could not solve.

1909, Johnson & Johnson complained to the British government that he was the real inventor of Portland cement, because asp Ding did not make cement with stable quality, so he could not be called the inventor of Portland cement. However, the British government did not agree with Johnson & Johnson's complaint and still maintained asp Ding's decision to own the Portland cement patent.