1824, British J. Aspding invented Portland cement, and modern cement concrete began. 1847, the French (lamport) made concrete boats and flowerpots with steel wires, and the most primitive reinforced concrete members appeared. 1874, Americans added scrap steel to concrete, which started the application of steel fiber in concrete. 19 10, H.F.Porter of the United States put forward the concept of "steel fiber" concrete, published a research report on short fiber reinforced concrete, and obtained a patent, suggesting that short fibers be uniformly dispersed in concrete to strengthen the matrix material. During the period of1911~1933, people in the United States, Britain, France, Germany and other countries successively applied for patents to improve the performance of concrete by uniformly mixing short iron wires and sawdust, but it was not applied to practical projects. Japan also conducted research in this field during World War II. It was not until 1963 that J.P.Romualdi and J.B.Batson published the Research Report on Fiber Concrete and put forward the fiber spacing theory that the research and application of steel fiber developed rapidly. In 1970s, China began to study the theory and application of "steel fiber reinforced concrete". Since 1980s, steel fiber has been widely used in many concrete projects such as roads, bridges and tunnels. Subsequently, the test methods, design and construction regulations of steel fiber reinforced concrete and industry standards of steel fiber for concrete were successively issued, which promoted the application of steel fiber in various construction projects in China.
1879, asbestos fiber cement appeared for the first time. 1900, Austrian Hasek used a rotary screen copier to manufacture asbestos cement board, which made asbestos cement industrialized. China began to produce asbestos-cement corrugated tiles in the mid-1930s. By 1970s, the industrial production of asbestos cement in the world reached its peak. After entering the mid-1970s, asbestos dust was found to be carcinogenic. Therefore, since the early 1980s, some developed countries have successively restricted the production and use of asbestos cement products, thus promoting the research and development of asbestos-free fiber reinforced cement products. In the past, the substitutes were mainly glass fibers, in addition to wood pulp fibers, polyacrylonitrile fibers, polyvinyl alcohol fibers and polypropylene fibers.
In the late 1950s and early 1960s, China Cement Industry Research Institute and other units explored the use of medium-alkali glass fiber to strengthen ordinary portland cement mortar or concrete. Pilukovich and others in the former Soviet Union have explored the use of alkali-free glass fiber to strengthen gypsum bauxite cement mortar; But it didn't succeed in the end, because the glass fiber couldn't stand the alkali erosion of cement hydrate and lost its reinforcement effect. 1967, the British Institute of Building Science (BRE) tried to manufacture alkali-resistant glass fiber containing zirconium, and production began in Britain in 197 1. The report published by British BRE in 1979 points out that although the mechanical properties of the components of this fiber material have little change in indoor dry environment, the mechanical properties of the components will still be greatly reduced in humid environment or exposed to the atmosphere. Therefore, in 1980s, relevant international scientific research institutions devoted themselves to improving the durability of glass fiber reinforced concrete (GRC). At the same time, western countries mainly take measures such as covering alkali-resistant glass fiber with protective layer and adding some polymer emulsion to cement. China Institute of Building Materials adopts the matching technology of alkali-resistant glass fiber and low alkalinity cement. The durability of GRC prepared by this technology is obviously better than that prepared by matching alkali-resistant glass fiber with ordinary portland cement, whether in hot and humid environment or exposed to the atmosphere for a long time. Therefore, it is called "double insurance" GRC technical route with China characteristics. Because it solves the durability problem of GRC well, it promotes the rapid development of GRC industry in China.
The development of synthetic fiber production technology has made substantial progress in the research and application of fiber concrete. In the early 1960s, S.Goldfein of the United States began to explore the use of synthetic organic fiber-polypropylene fiber as the admixture of cement concrete, and suggested that it be used in the US military to make explosion-proof structural members. In the early 1970s, Britain mixed polypropylene fiber into concrete to make pipes, plates and other products, and formulated relevant standards in the construction industry. In recent twenty years, developed countries, such as the United States, have developed and produced a series of monofilament synthetic fibers that can be mixed with concrete. For example, the United States vigorously develops synthetic fibers used to strengthen concrete, mainly polypropylene fibers and polyamide fibers; Germany and Japan have developed polyacrylonitrile fiber and polyvinyl alcohol fiber for strengthening concrete respectively. Grace Company of the United States and TORASUTO KIKAKUKI of Japan have also introduced corresponding fibers for asphalt concrete reinforcement. Patents US6569526 and CN140510 published by Grace Company of the United States in 2003 reported that a highly dispersed reinforced synthetic fiber can be applied to matrix materials such as concrete, mortar, shotcrete and asphalt concrete, which not only has good dispersibility, but also can obviously improve the strength of concrete materials. In the past, fibers mixed into concrete (such as most plant fibers) could not tolerate the strong alkalinity in concrete matrix materials, or could not be uniformly dispersed in concrete, or did not have certain high temperature resistance, and could not achieve the expected anti-cracking and reinforcement effect. The progress of synthetic fiber production technology has solved these problems. In recent years, although polypropylene fiber and polyamide fiber have the weakness of relatively low elastic modulus, they have high tensile strength and good alkali resistance, which can inhibit and reduce the occurrence and development of cracks in the initial plastic stage of concrete, and have made great progress in their application in concrete. When synthetic fiber is mixed into concrete, it improves the impermeability, frost resistance, impact resistance, ductility and wear resistance of concrete. Because of its good workability, simple operation and moderate price, it has been widely used in the construction field.
In 1970s, fiber reinforced concrete technology was introduced into China. Universities, research institutes and construction units in China have started the research work of mixing synthetic fiber into concrete, and it has been gradually applied in many construction projects. Subsequently, with the successful development of synthetic fibers for building in China, the application of synthetic fibers in concrete has made rapid development. The first national academic conference on fiber cement and fiber concrete held by china civil engineering society Fiber Cement and Fiber Concrete Professional Committee in Dalian from 65438 to 0986 correspondingly promoted various technical exchanges on the application of synthetic fibers in concrete nationwide. Since then, the annual academic conferences on fiber cement concrete have been held in Harbin (1988), Wuhan (1990), Nanjing (1992), Nanhai (1994), Chongqing (1996), and Chongqing. In 2008, the 12 annual meeting of fiber cement concrete will be held in Beijing, the venue of the 39th Olympic Games. I believe it will play a positive role in promoting the development and application of fiber cement concrete technology in China.
At present, the most widely used is synthetic fiber reinforced concrete, which comes from organic polymers. Organic polymers commonly used for spinning fibers include polypropylene (PP), polyamide (PA), polyester (PET), polyacrylonitrile (PAN) and polyvinyl alcohol (PVA). Synthetic fibers spun from these polymers usually have low elastic modulus, so they all belong to low elastic modulus fibers. In recent years, some high modulus fibers have been used to reinforce concrete, such as aramid fiber, ultra-high molecular weight polyethylene fiber, ultra-high molecular weight polyacrylonitrile fiber, ultra-high molecular weight polyvinyl alcohol fiber and so on. These fibers have high elastic modulus and tensile strength, and the effect of strengthening and toughening concrete is very obvious after adding concrete.
Fiber reinforced concrete can be widely used in plastering of building wallboard, floor slab, basement and external wall. Dams, reservoirs, canals and thin-walled water pipes of water conservancy projects; Pavement and deck pavement of road and bridge engineering; Tunnel; Bunkers, air-raid shelters and protective doors for military projects; Wharf, flood dike and precast concrete slab and pipe in port engineering.
With the formulation and promulgation of various design specifications, construction specifications and standards of fiber reinforced concrete, the application of fiber reinforced concrete will surely have greater development.