Coal Asphalt Replacement Petroleum Asphalt Road Construction Strategy is of Great Significance
The new road-use coal-tar pitch series modified materials independently developed by China have been popularized and applied in Shanxi Gaoling Expressway since last October. The inspection of road performance of coal tar pitch by the Highway Engineering Test Center of the Ministry of Communications shows that the performance of the series of materials is excellent, and it fully meets the relevant requirements for highway construction. Experts believe that after more than six months of practical application, coal tar pitch can be used as a substitute for petroleum asphalt. The large-scale production of coal-tar pitches is of strategic significance for realizing the comprehensive utilization of coal resources and alleviating the shortage of oil resources in China. However, as far as the current situation is concerned, the promotion of coal tar pitch still requires national policy support.
It is understood that a large amount of coal tar will be produced during the coking process. After further refining, these coal tars will be converted into coal pitch. Coal tar pitch is a complex compound containing polycyclic aromatic hydrocarbons. Among them, toxic substances such as quinones, benzopyrenes, etc., are emitted during the construction of hot mix asphalt mixture, which may cause environmental pollution and endanger people's health. In particular, the benzopyrenes contained in asphalt and bituminous cigarettes are strong carcinogens. Therefore, how to dry up these minimum products of coal is of great significance for realizing comprehensive utilization of resources and protecting the environment and human health.
Due to the high mixing temperature of hot mix asphalt, it is not suitable for the processing of coal-containing asphalt during mixing and paving. In the early 20th century, Germany developed a technology to modify coal pitch into road building materials. Since the 1970s, Germany, Switzerland, France, Poland and many other countries have produced and used coal-petroleum-based mixed asphalt. After a long period of use, it shows that the road surface has strong anti-deformation performance, good anti-wear properties, and can increase driving safety, and it maintains good performance under adverse weather conditions such as rain.
China began to study the application of coal asphalt in roads from the 1970s and 1980s. However, at the time it was limited to the technical level of coal chemical industry, the production of coal tar pitch was mainly based on low temperature coal tar pitch. According to the original research results, coal tar pitch is used for road construction and has poor low-temperature anti-cracking performance, poor temperature resistance and anti-ultraviolet ray, and the problem of volatilization of toxic gases during construction is not easy to solve. Based on this research, coal tar pitch is not considered suitable for the construction of high-grade highways.
To promote the development of coal resources, the Research Institute of Highway Research of the Ministry of Communications focused on the removal of carcinogens such as benzopyrene from coal tar pitch, developed a modifier with good effect of removing toxic components, and developed a low-temperature coal tar mixture that can be used for construction. Material technology. The hospital applied heavy modified coal tar, warm-mixed modified coal tar pitch, heavy-duty modified coal tar pitch and other products on Shanxi Gaoling Expressway. The project scale is about 5 kilometers. During the implementation of the project, the National Environmental Analysis and Testing Center monitored the construction environment of coal tar pitch. From the test results, the performance of the warm mix asphalt mixture with reduced mixing temperature is not lower than that of the hot mix asphalt mixture, and the temperature stability is also improved significantly due to the reduced construction temperature. The difficulty of construction is reduced, and construction quality is more easily ensured.
Shen Guolin, general manager of Shanxi Hengxin Chemical Co. , Ltd., told the reporter that coal-tar pitch as a binder for asphalt concrete pavement materials instead of petroleum asphalt is a good thing for coal chemical companies and highway investors. The coal tar pitch has low cost, the price is only 2,000 yuan/ton, and the petroleum bitumen is 4,000 to 5,000 yuan/ton, which can not only effectively alleviate the situation that China's road asphalt is in short supply, but also significantly reduce the construction cost of the highway project. If the current average thickness of asphalt pavements used in China's high-grade highways is calculated to be 16 centimeters, using coal tar pitch instead of petroleum tar pitch, about 400 tons of roads can be used per kilometer of 4-lane highway. The current annual output of coal tar pitch in China can be used for paving more than 10,000 kilometers. Asphalt road, the output value reached 10 billion yuan.
Niu Yufeng, a senior engineer at Shandong Dongming Petrochemical Group, said that after large-scale substitution of coal pitch into petroleum pitch, the market value of petroleum pitch as a product will be reduced, and petrochemical enterprises will have to adjust their production plans to reprocess the petroleum bitumen to extract the light oil. The yield of wax oil components, gasoline and diesel will increase by 60% (including liquefied gas and wax oil).
Experts said that the construction of coal bitumen as an alternative to petroleum asphalt is of great significance. However, the real “road†for coal tar pitches also requires the support of the state in industrial and environmental protection policies. Dr. Zhang Haiyan of the Institute of Highway Research of the Ministry of Transport stated that the current "Technical Code for Construction of Highway Asphalt Pavement" stipulates that coal tar pitch can only be used for translucent oils of all grades of highways. The current technical regulations for asphalt pavement construction also clearly stipulates the prohibition of the use of hot mixes. Coal tar pitch, which creates poor application channels. Only with national policy support, coal tar pitch can be extended to more ordinary asphalt pavements.
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