Since the invention of synthetic rubber and radial tires , the disposal of used tires has become a major problem for people. Modern tires are made up of fiber and steel and different types of vulcanized rubber. Decomposing very strong rubber products into basic components requires heavy-duty choppers, granulators and mills as well as cryogenic refrigeration equipment and separation equipment. When rubber prices are weak, it is very difficult to recover rubber profits. According to the 1996 data provided by the Washington Recycling Rubber Management Committee (STMC), the total number of waste tires was 266 million sets; recycling was 202 million sets; over 75% of the total was used as fuel for about 153 million sets; powdered rubber was used for 12.5 million sets Civil engineering projects utilized 150 million sets; mixed-stock new products utilized 8 million sets; exported 15 million sets; agricultural uses 2.5 million sets; and 1 million sets were used for other purposes. The following details the recycling and utilization of used tires in three aspects. Use of waste tyres 2.1 The most common method of using old tyres as fuel is to use them as fuel (TDF). According to the data provided by Goodyear Rubber Company, which has long advocated the use of TDF, there were 107 tyres used in the United States in early 1997. Fuel factory. Another 96 are doing combustion experiments. These include cement plants, lime plants, paper and pulp mills, power plants, foundries and smelters. According to a test report submitted to the Washington Environmental Protection Agency, gas emissions from TDF are lower than those from conventional fuels, such as coal. Of course, the TDF must be shredded before being supplied to the factory for easy delivery. Many users of scrap tires can accept complete tires, especially cement plants, because the steel in the tires is a component of the cement, TDF consumes 2.2 percent of the waste tires produced each year as powdered rubber, according to the Washington Recycling Rubber Management Committee (SIMC). ) Provide data that the production of rubber powder consumes about 12.5 million sets of tires each year. This is the second popular method of recycling old tires. Powder rubber consumption accounts for about 5% of the total. A lot of powder rubber is used on golf courses and sports fields. Particles 1/8 to 1/4 inch are the ideal material for soil bases. Rubber powder is added to soil or grass roots to protect the roots and stems of grass from frost and help ventilate and drain water. The price of this rubber powder is more than twice that of other uses. In the United States, 2 million pounds were sold in 1997 and will increase substantially each year. Rubber powder from 20 to 30 mesh can be used to press parts. The higher the mesh number, the finer and the higher the price. The traditional rubber powder market refers to the production of substitute products, such as cushions, baffles, and other manufacturers have used rubber powder to manufacture higher-tech products such as shoe roots, lawn dripping hoses, and automotive parts. Even rubber powders are combined with special binders or plastics to make new materials. According to Mr. Tang, an entrepreneur in Ohio Canton, a market is forming that rubber powder is used to heat up the roof or as a sealant. This area is currently being transformed from tar products to rubber products. Another rubber product is a protective material coated with steel bridges as a bridge. This use is really great. This water-based rubber coating can be used for seven years. "Other potential big markets include the use of floorboards, protective layers of underground pipes to replace foams, and raw materials for new tires." American tyre recovery company (ATR) has opened up several markets and even sold rubber powder to horse trainers as ground material for stables and runways. The company also developed new products for soil improvement, cultivating rubber powder to the surface of the soil and giving the grass a good growth bed to facilitate its growth. In addition, ATR also sold rubber powder to the Zhejiang Zheqing Paving Road. Recently, ATR installed new equipment to increase the production of rubber powder. The new production line aims to treat the rubber powder with a desulfurizer that is delinked. Debonding is the chemical process that destroys the sulfur bonds of vulcanized rubber and reduces the vulcanizate to a green colloidal state. The company predicts that once the desulfurization production line is put into operation, sales will increase significantly. In 1997, American Tire Recycler Co., Ltd. processed more than 1 million waste tires and produced 13 million pounds of products. It is one of the largest rubber powder production plants in the United States. ATR first crushed the waste tires from the carrier, made a 3/8-inch rubber sheet, sold the magnetically separated steel, and sold the screened fibers. Then, or at room temperature, the rubber is ground into 10 to 400 mesh mesh particles of different sizes, or frozen at a low temperature of 160°C and crushed into 100 mesh mesh (ultra-fine) micelles. No. 100 rubber powder can be used for pressing parts and other No. 100 rubber powder is suitable for mixing with new raw rubber. In general, the recycled rubber used in the United States accounts for an average of 1% to 2% of the total weight of tires, and North American Michelin has tried to use 5% of recycled rubber powder to manufacture new tires for Ford Motor Company. 2.3 Application of Civil Engineering The replacement of traditional building materials with waste tires began to spread after frustration. The United States has emerged a group of experts in this field, and some experts have had more than 35 years of experience in Zhejiang Qingqing Rubber Technology. The use of scrap tires dates back to the 1970s. Waste tires are used as breakwaters and artificial reefs. Since the early 1990s, more and more waste rubbers have been used in civil engineering. How waste tires are used for civil engineering purposes, one of the uses is to use waste tires instead of rock as embankment. Scrap tires are also used as light roadbed fillers, ribs on the walls to prevent freezing underneath the pavement, filtration and undersides of the gas storage system, and drainage beds in residential septic tanks. Tires are usually shredded and used. It can be cut into two or three inches in length. In different applications, civil engineering usually requires blocks no smaller than two inches in all directions. The smaller granular rubber is a powdered rubber, as described above. In the United States, with the expiration of certain patents, hybrid paving technology has been more widely used. For example, Granite Construction Co., one of the largest state-owned companies in the US and FNF Construction Co., Ltd. is the fastest growing mixed paving technology company. Prairie Valley Company is a mixed paving technology leader in the southern United States, and an international surface systems company. This shows that the rubber powder paving industry has great potential. Mr. Kan Shen, executive director of RPA, said that this industry has led to the development of more advanced and effective waste tire processing equipment. As a result, the contractor is more competitive than other materials in selecting waste rubber powder as a road paving material, and also greatly reduces the cost of Zheqing Green Rubber Paving Materials. There are 1800 to 20 million tires used for this purpose. Increased nearly 80% in the past two years. Based on the unique characteristics of the rubber block a light weight, good insulation, good water permeability and good compressibility. Using these properties, engineers used plastic blocks to solve many architectural problems, saving money and consuming large amounts of waste tires. However, fires in Washington and Colorado with roadblocks filled with waste rubber blocks caused the market to shrink to 5 million tires. The Waste Rubber Management Committee in Washington and the Tyre and Rubber Advisory Committee of the International Tyre and Rubber Association have called meetings. Members from the tire recycling industry, academic institutions, and the Federal Highway Administration Committee (FH-WA) committee survey in Washington revealed that in more than 70 similar projects this was only two fires. By comparing several factors that could cause fire, the Commission concluded that the self-heating of the roadbed may increase the likelihood of a fire. The key factor is the depth of the rubber roadbed exceeds 25 feet. The committee drafted a document “Regulations to Reduce the Spontaneous Combustion of Tyre Block Fillsâ€. The document has been passed by the Federal Highway Administration Committee. Regulations recommend that the height of the tire block filler should not exceed 3 m. Larger tire blocks should be used, and the minimum particle size should be limited. And limit the flow of air and water in the filling. After three years of hard work, the American Society for Testing and Materials issued a standard for the implementation of waste tires for civil engineering applications (ASTM D 627098). Here is an application example. The In-state Highway Authority (MTA) is preparing to establish a new three-dimensional road hub to smooth the road to the airport of Jet because of the jet. Because of the local thick soft clay foundation, the use of traditional earthwork to build roadbeds will sink into the clay layer. The engineering design Aldch and Dr. Humphrey solved this problem with scrap tire blocks. In order to comply with the above criteria, the designer chose two light tire blocks, each 3 m in length, to cover the air inside the rubber layer and cover the sides and top of the 7 water subgrade with 3 to 6 feet of mud. The key to limiting roadbed heating is the use of large debris to reduce the use of small particles, so designers use 12-inch maximum debris, where the weight of less than 1/4 inch does not exceed 1% of the total weight of the rubber. The Authority (MTA) collects scrap tires scattered throughout the state. After consultation, the State Environmental Protection Agency paid two-thirds of the waste tire processing fees. The State Expressway Authority saved US$300,000 by eliminating the use of polystyrene insulation panels. In the state, the state’s citizens also got rid of 1.2 million sets of scrap tires. New Standards for the Implementation of Waste Tire Civil Engineering Applications developed by the American Society for Testing Materials (ASTM D 6270-98) Washington’s Federal Highway Administration Committee (FHWA) issued a set of design rules to reduce the internal heat generated by waste rubber fillers; and throughout the country A series of education and technical training courses have brought this technology to a greater number of civilian engineering engineers and utility officials. 3 Conclusion As the saying goes, it is a mountain of stone that can be used to attack jade. The experience and technology in the recycling of used tires in the United States can be used by related companies and departments in China. We hope that China will catch up with the world advanced level as early as possible on the recycling and utilization of waste tires. 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Waste tire recycling has always been a big problem