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Cement is a cementitious material used in construction, and according to its chemical composition, it can be divided into three major categories, namely, silicate cement, alumina cement, and sulphur-alumina cement. Silicate cement is commonly used cement, also known as Portland cement, aluminate cement and alumina sulfate cement is a special purpose cement, this article is about the invention of silicate cement.
Some people like to call cement as the food of construction, which occupies an important position in human civilization. Now, the world production of cement has reached 2 billion tons, is an indispensable bulk product of modern society.
The invention of cement is the result of the accumulation of mankind in the long-term production and practice, is based on the development of the ancient building cementitious materials, has experienced a long historical process.
Ancient Western construction cementitious materials
In the thousands of years before the invention of cement, the West initially used clay as a cementitious material. The ancient Egyptians used mud from the Nile River to build uncalcined earth bricks. To increase strength and minimize shrinkage, the mud was mixed with sand and grass. Buildings constructed with this clay are not water-resistant, can not withstand the rain and river wash, but in dry areas can be preserved for many years.
Around 3000 to 2000 BC, the ancient Egyptians began to use calcined gypsum as a building cementing material, the construction of the ancient Egyptian pyramids used calcined gypsum. In 30 BC, before Egypt was incorporated into the Roman Empire, the ancient Egyptians used calcined gypsum for masonry.
The ancient Greeks, unlike the Egyptians, used calcined lime as the cementing material in their buildings. In 146 BC, the Roman Empire annexed Greece, while inheriting the Greek tradition of production and use of lime. Romans used lime by first dissolving lime with water, mixing it with sand to make mortar, and then using this mortar to build buildings. Some of the Roman buildings with lime mortar are so strong that they have survived to the present day.
The ancient Romans improved the process of using lime by mixing it not only with sand, but also with finely ground volcanic ash, and in areas where volcanic ash was not available, it was mixed with finely ground bricks that had the same effect as volcanic ash. This mortar is a great improvement over the "lime-sand" two-component mortar in terms of strength and water resistance, and is more durable for both ordinary buildings and buildings in water. Some people call "lime - volcanic ash - sand" three-component mortar "Roman mortar".
The knowledge of the Romans of the manufacture of mortar was widely spread. This three-component mortar was commonly used in France and England in ancient times to build all kinds of buildings.
In the history of European architecture, the use of "Roman mortar" continued for a long time. However, in the 9th, 10th and 11th centuries AD, the mortar technology was almost lost. During these long years, the lime used for the mortar was poorly calcined limestone blocks, and the crushed bricks were not finely ground and were of poor quality. By the 12th, 13th and 14th centuries AD, the quality of lime calcination gradually improved, and the crushed bricks and volcanic ash were also finely ground, restoring the quality of the "Roman mortar" to its original level.
Ancient Chinese building cementitious materials The development of Chinese building cementitious materials has its own unique and a long historical process.
"White ash surface"
As early as 5000 to 3000 BC in the Neolithic period of the Yangshao culture, there are people with "white ash surface" painted caves, caves, the ground and the four walls, so that it becomes smooth and hard. "White ash surface" is named because of the white powder, which is made of natural ginger stone grinding fine. Ginger stone is a kind of limestone block with high silica content, often mixed in loess, which is a calcium nodule in loess. The "white ash surface" is the earliest construction cementing material in ancient China that has been discovered so far.
Yellow mud mortar 16th century BC Shang Dynasty, the rapid development of crypt construction to wooden buildings, this time in addition to continue to use "white ash surface" wipe the ground, began to use yellow mud mortar masonry adobe walls. In the Warring States period from 403 BC to 221 BC, it appeared to use grass mixed with yellow mud slurry to build walls, and also used it in the earth wall lining wall bricks. In the history of Chinese architecture, "white plaster surface" was eliminated very early, while yellow mud and grass-mixed yellow mud as a cementitious material has been used until the modern world.
Lime Lime appeared in the 7th century BC in the Zhou Dynasty, the Zhou Dynasty lime is made from the shell of a large clam burned. The main ingredient of the clam shell is calcium carbonate, and it was calcined until all the carbonic acid gas escaped to become lime. It is written in Zuo Zhuan (左传), "In August of the second year of Cheng Gong (635 BC), Duke Wen of Song died and was buried with mirage ash". Mirage ash is burnt with clam shells made of lime material, in the Zhou Dynasty has been found to have good moisture absorption and moisture properties and gelling properties. In the ancient times, which advocated generous burial, mirage ash was used as moisture-absorbent and moisture-proof materials in tombs in order to preserve the burial materials for a long time, and mirage ash was used as cementing materials in the construction of tombs to build mausoleums, etc. In the Ming Dynasty, "Tian Gong Kaifu" was published. In the Ming Dynasty, "Tian Gong Kai Wu" book has "burnt the diagram of the room method", which indicates that the production and use of mirage ash, since the Zhou Dynasty to the Ming Dynasty has not been lost, passed down for a long time in the history of China.
By the Qin and Han Dynasties, in addition to wooden buildings, masonry buildings occupy an important position. Masonry structure must be excellent performance of cementitious materials for masonry, which prompted the rapid development of the lime manufacturing industry, have to use all over the collection of limestone burned lime, lime production points came into being. At that time, the use of lime is first mixed with water to make lime slurry, and then use the slurry masonry, brick walls and masonry arches, as well as painting the wall. In the Han Dynasty, the use of lime has been very common, the use of lime masonry masonry structure can build multi-storey pavilion.
The Great Wall of China was built from the 7th century BC to the 17th century AD, with more than 20 dynasties presiding over and participating in its construction. Qin, Han and Ming dynasties built the longest, in the total length of 50,000 kilometers of the Great Wall built more than 5,000 kilometers. During these three dynasties, lime cementing materials were developed to a high level and were used in large quantities in the construction of the Great Wall. Therefore, many sections of the Great Wall, later found that it is made of lime masonry.
The Ming Dynasty "Tian Gong Kaifu" book also detailed the production method of lime. Qing Dynasty "construction method of the original" book is recorded in the lime burning process and the relationship between the performance of lime. These records show that China to the Ming and Qing dynasties have accumulated a relatively rich knowledge of lime production and use.
"Triad"
In the 5th century AD, during the Northern and Southern Dynasties in China, there was a building material called "Triad", which consisted of lime, clay and fine sand. In the Ming Dynasty, there were lime, ceramic powder and gravel composed of "three combined soil". In the Qing Dynasty, in addition to lime, clay and fine sand composed of "triad", there are lime, slag and sand composed of "triad". Qing Dynasty "Palace-style stone bridge practice" book on the "triple earth" ratio is explained: "gray earth that is mixed with lime and loess, or so-called triple earth"; "gray earth according to the four-six mixing, lime 40%, loess 60%! ". To modern eyes, "three together soil" is also to lime and loess or other volcanic materials for cementitious materials, fine sand, gravel or slag as filler concrete. "Triple clay" and the ancient Roman three-component mortar, that is, "Roman mortar" has many similarities.
Since its inception, triturated concrete has been used for floors, roofs, foundations, and ground bedding. "After being tamped, it not only has high strength, but also good waterproofing, and in the Qing Dynasty, it was also used for tamping dams.
In the European continent to adopt the "Roman mortar" when, far away from the ancient countries of the East China is also similar to the "Roman mortar" "triple soil", this is a very This is a very interesting historical coincidence.
Lime mixed with organic materials of cementitious materials in ancient China, a distinctive feature in the development of cementitious materials for construction is the use of lime mixed with organic materials of cementitious materials, such as "lime - glutinous rice", "lime - tung oil", "lime - blood". Lime - blood", "lime - hyacinth", and "lime - glutinous rice - alum" and so on. In addition, in the use of "triad soil", mixed with glutinous rice and blood and other organic materials.
According to folklore, the Qin Dynasty in the construction of the Great Wall project, the use of glutinous rice juice masonry. Archaeological findings, the North and South Dynasties period of Henan Dengxian portrait of the brick wall is lined with starch-containing gelatine; Shaolin Temple in Dengfeng County, Henan, the Northern Song Dynasty, Xuanhe two years, the Ming Dynasty, Hongzhi twelve years and Jiajing forty years of different years of the tower, in the construction of the use of lime mixed with starch as a gelatine. Song Hui Yao" records, in 1170 A.D. South Song Qian Dao six years of construction and the state city, "the walls of the surface of the city with five layers of brick and ash, glutinous rice porridge and gray pavement and building yagura, the Committee are majestic, durable and strong." The Ming dynasty construction of Nanjing is the world's largest masonry city wall, with stone as the foundation, on the rammed earth, outside the huge brick, with lime as cementitious material, in important parts of the lime and glutinous rice juice grout, the upper part of the wall with tung oil and soil mixed and knotted top, very strong. The use of tung oil or glutinous rice juice mixed with alum and lime made of cement, its adhesion is very good, often used to repair rockery, so far in the repair of ancient buildings are still in use.
Mixed with organic materials and "three combined soil" for the building of the work method, in the history of the material has been seen repeatedly. The Ming Dynasty, "Tian Gong Kaifu" book recorded: "used to Xiang tomb and cisterns, one point of gray into the river sand, two points of loess, with glutinous rice, sheep peaches and vine juice and uniform, by building strong, never Seno bad, called the triad of earth". In China's architectural history, the Qing Dynasty Kangxi Qianlong years, Beijing Lugou Bridge, north and south bank, with glutinous rice juice mixed with "triple soil" building embankment for miles, so that the southern suburbs of Beijing from now on free from flooding. In the history of stone bridge construction, it is recorded that the stone bridge was built by mixing glutinous rice and cow's blood with "triple soil", which was as strong as granite after solidification. Glutinous rice juice mixed with "triple soil" building is very hard, and toughness, with an iron pickaxe planing will burst out of the sparks, and some even use gunpowder in order to blow up.
China has a long history of brilliant achievements and important contributions to the creation of human civilization. Joseph Lee, the famous British historian of science, wrote in his book "The History of Science and Technology in China": "Between the third and thirteenth centuries AD, China maintained a level of scientific knowledge beyond the reach of the West"; "China's inventions and discoveries were far superior to those of Europe at the same time, especially before the 15th century. China's inventions and discoveries far surpassed those of its European contemporaries, especially before the 15th century". Ancient Chinese construction cementitious materials development process is, from the "white ash surface" and yellow mud slurry start, development to lime and "triple clay", and then to the development of lime mixed with organic materials of cementitious materials. From this historical process can be drawn with the historian of science Joseph Lee similar conclusions, ancient Chinese construction cementitious materials have their own glorious history, in the process of basic synchronization with the development of the Western ancient construction cementitious materials, due to the extensive use of lime and organic materials combined with the cementitious materials and appear to be slightly higher.
However, in recent centuries, China lagged behind, especially to the end of the Qianlong period of the Qing Dynasty, that is, after the end of the 18th century, science and technology and the West is getting bigger and bigger gap. Ancient China's development of building cementitious materials, lime mixed with organic materials to reach the stage of cementitious materials and then stop, not in this base point to step forward. Western ancient construction cementitious materials in the "Roman mortar" on the basis of continued development, towards the direction of the modern cement continues to improve, and finally invented cement.
The invention of modern cement
The invention of modern cement has a gradual process, not overnight.
Water-hardened lime in the middle of the 18th century, the British maritime industry has been more developed, but the ship reefs and beaches and other maritime accidents occur frequently. In order to avoid accidents at sea, the use of lighthouses for navigation. At that time, the British construction of lighthouses have two kinds of materials: wood and "Roman mortar". However, timber is flammable and easy to rot in seawater; although "Roman mortar" has certain water resistance, it can not withstand the erosion and scouring of seawater. Since the materials were not durable in seawater, lighthouses were often damaged, ships could not navigate safely, and the rapidly developing shipping industry encountered major obstacles. In order to solve the problem of shipping safety, the search for materials resistant to sea water erosion and the construction of durable lighthouses became a priority in the economic development of Britain in the 18th century 50's. The British Parliament spared no expense in this regard. The British Parliament spared no expense in recruiting talented people. Respected as the father of British civil engineering Smithsonian (J. Smeaton) was hired to undertake the task of building lighthouses.
1756 Smeaton in the process of building lighthouses, research "lime - volcanic ash - sand" three-part mortar in different limestone on the performance of the mortar, found that the limestone containing clay, calcined and finely ground treatment, water made of mortar can be slowly hardened in seawater, the strength of the more "Roman mortar" is much higher, can withstand the wash of sea water. Smithsonian used the newly discovered mortar to build the world-famous Eddystone (Eddys-tone) lighthouse in Plymouth Harbor.
Lime made from clay-bearing limestone is known as hydraulic lime. Smithson's discovery was a great leap forward in the accumulation of knowledge in the invention of cement, which not only contributed to the British maritime industry, but also played an important role in the invention of "Portland cement". However, the success of Smithson's research in hydraulic lime, did not get widely used, then a lot of use is still composed of lime, volcanic ash and sand "Roman mortar".
Roman cement in 1796, the Englishman Parker (J. Parker) will be called SepaTria clay limestone, after grinding fine made of material balls, calcined at a temperature higher than the burning lime, and then made into a fine grinding cement. Parker called this cement "Roman Cement" (RomanCement) and obtained a patent for it. "RomanCement" set faster and could be used in projects in contact with water, and was widely used in the United Kingdom until it was replaced by "Portland cement".
Almost at the same time as the creation of "Roman cement", the French used the Boulogne region of the chemical composition close to the composition of the modern cement marl also produced cement. This kind of natural marl whose chemical composition is close to that of modern cement is called hydraulic marl, and the cement made of this marl is called natural cement. Natural cement was also made in the United States from marl in the Rosendale and Louisville areas. In the 1880s and a long time after, natural cement in the United States has been widely used in the construction industry has played a very important role.
British cement British Foster (J. Foster) is a dedicated cement researchers. He will be two weight chalk and a weight of clay mixed with water and wet grinding into slurry, sent to the tank for precipitation, set the precipitate in the atmosphere dry, and then put into the lime kiln calcination, the temperature of the material in the carbonic acid in the complete volatilization of the carbon dioxide gas shall prevail, burned into the product was light yellow, after cooling fine grinding into cement. Foster called the cement "British Cement" (BritishCement), in October 22, 1822 to obtain the British patent No. 4679.
"British Cement" due to lower calcination temperature, its quality is obviously not as good as "Roman cement", so the price is low, the sales volume is not large. This kind of cement is not popularized in large quantities, but its manufacturing method is the prototype of modern cement manufacturing, which is another major leap in the accumulation of knowledge of cement. Foster also contributed to the invention of modern cement.
Portland cement (silicate cement) October 21, 1824, Leeds (Leeds), England, the city of plasterer Aspdin (J. As-pdin) to obtain the United Kingdom No. 5022 of the "Portland Cement" patent certificate, thus becoming a world-famous inventor of cement.
His patent certificate describes the "Portland cement" manufacturing method is: "the limestone pounded into a fine powder, with a certain amount of clay, mixed with water and stirred by hand or mechanical homogeneity into mud. Put the mud on the plate, heat and dry. The dry material into a block, and then loaded into the lime kiln calcination, burned to the limestone carbonate gas all escape. The calcined blocks are then cooled and crushed to make cement. When the cement is used, a small amount of water is added and mixed into a mortar of appropriate consistency, which can be used in a variety of different workplaces."
The color of the cement after hydration and hardening is similar to the color of the stone used for construction in the Portland area of the United Kingdom, which is why it is called "Portland cement".
Aspdin built the first Portland cement plant in Wakefield, England. Later, his son built another plant in Grasshead, England, and in 1856, another plant in Germany, where he spent the rest of his life.
Aspdin father and son of the "Portland cement" production method for a long time to keep secret, to take a variety of secrecy measures: in the factory around the construction of a high wall, without the permission of their father and son, no one can not enter the factory; workers are not allowed to go to their own workplaces outside of the lot to walk around; in order to create the illusion of often with copper sulfate or other powders in the plate, in the loading of copper sulfate. In order to create an illusion, copper sulphate or other powders were often carried in trays and sprinkled on the dry material when the kiln was loaded.
The method of manufacture of "Portland cement" described in Aspdin's patent certificate is not fundamentally different from that of Foster's "English cement", and the temperature of calcination is based on the complete volatilization of carbonic acid gas in the material. According to the general knowledge of cement production, the quality of "Portland cement" made under such temperature conditions cannot be better than that of "British cement". However, in the market, "Portland cement" is more competitive than "British cement", and when the Thames tunnel project was rebuilt in 1838, the price of "Portland cement" was higher than that of "British cement". "When rebuilding the Thames Tunnel in 1838, the price of Portland Cement was much higher than that of British Cement, but the owner still chose Portland Cement. Obviously, Aspdin for reasons of confidentiality in the patent certificate did not write "Portland cement" production technology, he actually mastered the knowledge of cement production than the patent certificate shows. Aspdin must have used higher calcination temperatures in the plant, otherwise the cement would not have hardened with the same color as the Portland stone, and the product would not have been as competitive.
However, according to the patent certificate and related information, Aspdin did not know the exact firing temperature of "Portland cement" and the correct proportion of raw materials, so the quality of the product produced by his factory was very unstable, and even caused some buildings to collapse due to the quality of the cement.
In Britain, another cement research genius of the same era as Aspdin was I.C. Johnson. He is the manager of the British Swan Valley White Company, specializing in the manufacture of "Roman cement" and "British cement". 1845, Johnson experiments in a chance to find, calcined to contain a certain amount of vitreous cement burnt block, after grinding fine with very good Water hardness. It was also discovered that the presence of lime in the fired product caused the cement to crack after hardening. Based on these unexpected discoveries, Johnson established two basic conditions for cement manufacture: firstly, the kiln temperature had to be high enough to make the blocks contain a certain amount of vitreous and be blackish-green in color; secondly, the proportions of the raw materials had to be correctly fixed, the inside of the blocks could not contain an excessive amount of lime, and the cement could not crack after hardening. These conditions ensure the quality of "Portland cement", and solved the problem of unstable quality that Aspertin could not solve. From then on, the basic parameters of modern cement production have been discovered. 1909, Johnson, at the age of 98, filed a complaint with the British government, saying that the cement he made in 1845 was the real "Portland cement", and that Aspdin had not made a stable quality of cement and could not be called the inventor of "Portland cement". Aspdin did not make a consistent quality of cement and could not be called the inventor of "Portland cement". However, the British government did not agree with Johnson & Johnson's complaint and upheld Aspdin's decision to patent Portland cement. Johnson's work was highly regarded by his British and German counterparts as an indelible contribution to the invention of Portland cement.
The first industrial revolution in the history of mankind occurred in Europe in the century, promoting the rapid social and economic development of the western countries, and the pace of development of cementitious materials for construction also accelerated. Western countries in the "Roman mortar" on the basis of the 1756 discovery of water-hardened lime; 1796 invention of "Roman cement", as well as similar natural cement; 1822 appeared in the "British Cement "In 1824, the British government issued the first patent for "Portland cement". Contemporary construction food --- "Portland cement" (silicate cement) was born in the West, while embarking on a journey of continuous improvement.