The invention of modern cement has a step-by-step process, not overnight.
Hydraulic lime
/kloc-In the middle of the 0/8th century, the British maritime industry was developed, but shipwrecks such as hitting rocks and beaches occurred frequently. In order to avoid shipwrecks, lighthouses are used for navigation. At that time, there were two kinds of materials for building lighthouses in Britain: wood and "Roman mortar". However, when exposed to seawater, wood is flammable and perishable; Although "Roman mortar" has certain water resistance, it can't stand the corrosion and erosion of seawater. Because materials are not durable in seawater, lighthouses are often damaged, and ships can't sail safely, and the fast-developing shipping industry encounters major obstacles. In order to solve the problem of shipping safety, from 65438 to 2008, finding materials resistant to seawater erosion and building durable lighthouses became the top priority of British economic development in the 1950s. In this regard, the British Parliament spared no expense in hiring talents. J Smeaton, an engineer who is revered as the father of British civil engineering, was hired to build a lighthouse.
1756 During the construction of the lighthouse, Smithton studied the influence of different limestone in the "lime-pozzolana-sand" three-component mortar on the performance of the mortar. It is found that limestone containing clay can be hardened slowly by adding water after calcination and fine grinding, and its strength in seawater is much higher than that of "Roman mortar", which can withstand seawater erosion. Smithton built the world-famous Eddie Si Tong Lighthouse in Plymouth Harbor with newly discovered mortar.
Lime made of clay and limestone is called hydraulic lime. Smithton's discovery was a great leap in knowledge accumulation in the process of cement invention, which not only contributed to the British navigation industry, but also played an important role in the invention of "Portland cement". However, the hydraulic lime successfully studied by Smithton has not been widely used. At that time, "Roman mortar" composed of lime, volcanic ash and sand was still widely used.
Roman cement
1796, J. Parker, an Englishman, ground a clay limestone called Sepa Tria into pellets, calcined it at a temperature higher than that of burning lime, and then ground it into cement. Parker called this cement "Roman cement" and obtained the patent right of this cement. "Roman cement" can be used in projects in contact with water because it sets rapidly. It was widely used in Britain until it was replaced by Portland cement.
Almost at the same time of producing "Roman cement", the French also used marl to make cement with chemical composition close to modern cement in boulogne. This kind of natural marl close to modern chemical composition is called water marl, and the cement made of this limestone is called natural cement. Americans also make natural cement from marl in Rosendale and Louisville. In the 1980s of 19 and for a long time thereafter, natural cement was widely used in the United States and once occupied a very important position in the construction industry.
British cement company
J. Foster is an Englishman and a researcher devoted to cement. He mixed two parts by weight of chalk and one part by weight of clay, then wet-grinded it into slurry with water, sent it to a tank for precipitation, dried it in the atmosphere, and then put it into a lime kiln for calcination. The temperature is based on the complete volatilization of carbonic acid gas in the material, and the sintered product is light yellow, which is finely ground into cement after cooling. Foster called this cement "British cement" and obtained British Patent No.4679 on1October 22nd, 1822+65438.
Due to the low calcination temperature, the quality of "British cement" is obviously not as good as that of "Roman cement", so the price is low and the sales volume is not large. Although this kind of cement has not been widely popularized, its manufacturing method is the embryonic form of modern cement manufacturing and another leap in cement knowledge accumulation. Foster also contributed to the invention of modern cement.
Portland water (Portland cement)
1824101October 2 1 day, J. Aspdin, a plasterer in Leeds, England, obtained the patent certificate of "Portland Cement" No.5022, thus becoming the immortal inventor of cement.
The manufacturing method of "Portland cement" described in his patent certificate is: "Mash limestone into fine powder, add a certain amount of clay, mix it with water, and stir it into slurry manually or mechanically. Put the mud on a plate and heat it to dry. The dry material is crushed into blocks, and then put into a lime kiln for calcination until the carbonic acid gas in limestone completely escapes. The calcined clinker is cooled, crushed and ground to make cement. When cement is used, a small amount of water is added and stirred into mortar with appropriate consistency, which can be applied to various workplaces. "
The color of this cement after hydration and hardening is similar to the color of building stone in Portland, England, so it is called "Portland cement".
Aspirin built the first Portland cement plant in wakefield, England. Later, his son built another factory in Graz Head, England, and another factory in Germany 1856, where he spent his old age.
Asp Ding and his son kept the production method of Portland cement secret for a long time and adopted various secrecy measures: building a high wall around the factory, and no one can enter the factory without his father's permission; Workers are not allowed to walk outside their jobs; In order to create illusion, copper sulfate or other powder is often put in a plate and sprinkled on dry materials when it is put into a kiln.
There is no essential difference between the manufacturing method of Portland cement described in the aspirin patent certificate and Foster's British cement, and the calcination temperature is based on the complete volatilization of carbonic acid gas in the material. According to the common sense of cement production, the quality of "Portland cement" made at this temperature cannot be better than that of "British cement". However, "Portland cement" is more competitive than "British cement" in the market. 1838 when the Thames tunnel was rebuilt, the price of "Portland cement" was much higher than that of "British cement", but the owner chose "Portland cement". Obviously, aspirin did not put all the production technologies of portland cement on the patent certificate for confidentiality reasons, and he actually knew more about cement production than indicated in the patent certificate. Aspirin must have adopted a higher calcination temperature in engineering production, otherwise the hardened cement would not have the color of Portland stone, and its products would not have such high competitiveness.
However, according to the contents contained in the patent certificate and related materials, aspirin failed to master the accurate firing temperature and the correct proportion of portland cement raw materials. Therefore, the quality of products produced by his factory is very unstable, and even some buildings collapsed because of cement quality problems.
In Britain, another cement research genius at the same time as aspirin was Johnson. He is the manager of White Company in Swan Valley, England, specializing in "Roman Cement" and "British Cement". During the period of 1845, Johnson & Johnson accidentally found in the experiment that the cement clinker containing a certain amount of glass body after calcination has very good hydraulic property after grinding. In addition, we found that if the sintered product contains lime, the cement will crack after hardening. According to these unexpected findings, Johnson & Johnson Company has determined two basic conditions for cement manufacturing: first, the temperature of the kiln must be high enough to make the sintered block contain a certain amount of glass and be dark green; Secondly, the proportion of raw materials must be correct and fixed, and the burnt product cannot contain excessive lime, and the cement cannot crack after hardening. These conditions ensure the quality of portland cement and solve the problem of unstable quality that aspirin can't solve. From then on, the basic parameters of modern cement production were found.
1909, when Johnson & Johnson was 98 years old, he complained to the British government that the cement he made in 1845 was really "Portland cement", but aspirin did not produce 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 the decision that aspirin had the patent right of "Portland Cement". Colleagues in Britain and Germany spoke highly of Johnson's work and thought that he had made an indelible and important contribution to the invention of Portland cement.
The first industrial revolution in human history took place in Europe in the18th century, which promoted the rapid development of social economy in western countries and accelerated the development of building cementing materials. On the basis of "Roman mortar", 1756 hydraulic lime was discovered in western countries; 1796 invented "Roman cement" and similar natural cement; 1822 "British cement" appeared; 1824, the British government issued the first "Portland cement" patent. Portland cement, the "grain" of contemporary architecture, was born slowly in the west and embarked on a journey of continuous improvement.