What Are Different Types of Asphalt?

Asphalt is a dark brown complex mixture composed of hydrocarbons of different molecular weights and their non-metallic derivatives. It is a kind of highly viscous organic liquid. It is liquid with a black surface and is soluble in carbon disulfide. Asphalt is a water-proof, moisture-proof and anti-corrosive organic gelling material. Asphalt can be divided into three types: coal coke pitch, petroleum pitch and natural pitch: Among them, coal coke pitch is a by-product of coking. Petroleum pitch is a residue after distillation of crude oil. Natural asphalt is stored underground, and some form mineral deposits or accumulate on the surface of the earth's crust. Asphalt is mainly used in coatings, plastics, rubber and other industries as well as paving the road.

On October 27, 2017, a preliminary list of carcinogens published by the World Cancer Organization's International Cancer Research Agency was prepared. References for asphalt and occupational exposure to oxidized asphalt and their emissions during roofing are on the 2A carcinogens list. Exposure to straight run asphalt and its emissions, and occupational exposure to hard asphalt and its emissions while doing asphalt mortar work are on the list of Class 2B carcinogens. ^[1]

Chinese name: asphalt
English name: Bitumen, Asphalt
CAS Registry Number: 8052-42-4
EINECS registration number: 232-490-9
Melting point: No fixed melting point
Boiling point: <470
Water soluble: not soluble in water
Density: 1.15-1.25

Exterior: Semi-solid or liquid state
Flash point: 204.4
Risk description: Health hazard: moderate toxicity
To source: Coal and oil
Ingredients: Asphaltene and resin
Content: 99.48%
Lower explosion limit: 30 (g / cm3)
Electrical conductivity: Insulator (at room temperature)

Asphalt composition structure

The most commonly used method in recent years is to separate the asphalt into four components: saturated, aromatic, gum, and asphaltenes according to the method of L.W. Colbert. There is a certain regularity between the content of each component in asphalt and asphalt and technical properties, as shown in the figure. ^[2]

According to the colloidal structure, with the decrease of the saturation and aromatic content of the dispersion medium, the increase of the content of the protective substance colloid and the dispersed phase asphaltene, the asphalt changes from a sol structure to a sol gel structure to a gel structure. The penetration of the bitumen technical index will decrease, and the softening point will increase. And when the proportion of each component in the asphalt is coordinated, the best ductility can be obtained. However, the above rules only apply to the asphalt obtained from the same oil source and the same process.For example, in Table 1, the asphalt is Daqing crude oil. Asphalts, even if they have similar asphalt component content, their technical properties can be very different. The reason for these phenomena is that the asphalts obtained by different oil sources and processes, although their chemical components can be very close, but their chemical structures are not the same, and their solubility parameters are different. That is, the compatibility of the components is different, so different colloidal structures are formed, so their technical properties are also different. ^[2]

Asphalt (8 photos)

Asphalt is a water-repellent material. It is impermeable to water and is almost insoluble in water, acetone, ether, and dilute ethanol. It is soluble in carbon disulfide, carbon tetrachloride, and sodium hydroxide.

Asphalt and its smoke are irritating to the skin and mucous membranes, and have phototoxic and carcinogenic effects. The toxicity of three major asphalts in China: coal coke asphalt> shale asphalt> petroleum asphalt, the former two are carcinogenic. The main skin damages of asphalt are: phototoxic dermatitis, which is limited to the exposed parts of the face and neck; melanosis, which is usually symmetrically distributed in the exposed area, and is flaky, brown-dark brown-brown-black; occupational Acne; verrucous vegetation and accidental thermal burns. In addition, there are still systemic symptoms such as dizziness, bloating, headache, chest tightness, fatigue, nausea, and loss of appetite, and eye, nose, and throat irritation symptoms.

Asphalt applications

In civil engineering, asphalt is a widely used waterproof material and anticorrosive material. It is mainly used for waterproofing of roofing, ground and underground structures, and anticorrosion of wood and steel. Asphalt is also a widely used pavement structure cementing material in road engineering. It can be used in proportion to different composition of mineral materials to build asphalt pavements of different structures. Expressways are widely used.

Asphalt industry analysis

In 2013, the domestic asphalt output was 1993.51 million tons, a year-on-year increase of 9.71%. Compared with domestically produced asphalt, the price of imported asphalt is relatively high, which in turn boosts the demand for domestically produced asphalt and promotes the utilization of domestic asphalt capacity. It is expected that domestic asphalt production will continue to increase in 2014, but as demand improves, the overall surplus situation will change.

The upstream of the asphalt industry is petrochemicals, coal and modifiers and emulsifiers, and the downstream is highways, waterproof building materials, airport construction and municipal engineering road construction.

In the complete petrochemical industry chain, the front-end products of petroleum pitches are major products such as ethers, alkanes, hydrocarbons, and benzene. Petroleum pitches, which are the back-end products of crude oil processing, can be obtained by coking process.

For the asphalt industry, the impact of upstream industries on it is mainly reflected in fluctuations in crude oil prices and changes in crude oil processing capacity that have caused fluctuations in petroleum asphalt production and product prices.

The mild recovery of the global economy in 2014 will drive crude oil demand, and the expansion of the oil pipeline from the Cushing area to the Gulf of Mexico refinery in the past two years has alleviated local inventory pressure to a certain extent and boosted WTI oil prices. Therefore, despite the impact of the US Federal Reserve's withdrawal from QE and increasing supply, the center of gravity of international crude oil prices is expected to move up slightly in 2014. It is expected that the annual fluctuation range of WTI crude oil prices will be in the range of 90-115 USD / barrel, which will support the price of asphalt futures.

From the perspective of downstream demand, asphalt products are mainly used in the laying of highways, municipal roads, bridges and airports, among which the asphalt consumption of highway construction accounts for 82%. In the case of a certain capacity, the increase in downstream demand will further promote the increase in the price of asphalt products, and conversely, it will bring down prices.

Affected by the tight monetary policy and insufficient funding in 2013, some road construction projects were stranded, resulting in a limited increase in asphalt demand in 2013.

However, the construction cycle of road construction is generally 3-4 years, and the laying of asphalt is mainly concentrated at the end of construction. Therefore, the demand for asphalt will gradually improve in the last two years of the "Twelfth Five-Year Plan".

Broad prospects for the asphalt industry

Since the reform and opening up, China's economy has maintained rapid growth, highway transportation construction has made rapid progress, and China's road asphalt production enterprises have also developed rapidly. In particular, heavy traffic asphalt and modified asphalt have made qualitative leap from scratch, from small to large, and from small to many, and have made great contributions to China's road construction.

Among them, asphalt pavement is generally divided into three types: preventive maintenance, corrective maintenance, and emergency maintenance. These three types of maintenance can be selected according to the use of the pavement, and each type of maintenance needs to choose different maintenance methods and equipment. The differences between the three maintenance measures are mainly reflected in the pavement conditions and the length of time that they are open to traffic. Of course, there is no clear boundary between the three.

Preventive maintenance refers to maintenance before the road surface is damaged; corrective maintenance refers to repairing local damage to the road surface or dealing with certain specific diseases; emergency maintenance is a measure in emergency situations, such as road surface cracks and severe pits Needs immediate repairs to open to traffic.

Nowadays, China's asphalt industry has entered a stage of rapid development of large-scale and centralized, and people's understanding of asphalt is becoming more and more familiar, because the amount of asphalt is not only large, but also very extensive. The avenues here and high speeds are inseparable from the use of asphalt, so asphalt recycling has become a very popular topic in people's mouths. Especially in the mouth of men, some people regard recycling asphalt as a cause, and even some people Wealthy because of asphalt recycling!

However, the development scale of asphalt is compared with the demand of our domestic market. The Chinese asphalt market is still in short supply, especially those high-end modified asphalt markets are still to be discovered by talented people in China. China s ordinary road asphalt production There are many manufacturers, but there are fewer professional asphalt manufacturers. We should gradually increase the professional asphalt manufacturers to make up for the growing professional asphalt market demand.

Asphalt history

Classical Asphalt

Archeological studies have found that as early as the early 1200s of the classical period, people have begun to use natural asphalt, using asphalt as an ornament in the production of weapons and tools, to add color to sculptures. Especially in Mesopotamia, bitumen is widely used due to its sufficient content. The Sumerians who lived there covered the vessels and boats with natural asphalt. In addition, they have begun to use natural asphalt as a binder in clay bricks.

This is a schematic cross section of a gorgeous road in Babylon. The burnt brick is painted with asphalt, and the top slate is laid flat

Cross section of a magnificent road in Babylon Asphalt surface. This gorgeous road can be regarded as a pioneer of modern asphalt concrete roads. During that millennium, the range of applications of asphalt was expanded so that in India and Europe close to Mesopotamia, natural asphalt was used as a sealing material for baths, boats, canals, toilets and river banks. In the Assyrian and Babylonian empires of the seventh century BC, asphalt was already used in road works. At that time, bitumen was used as a jointing material and a daubing material to decorate and strengthen the Huadao. Since then, bitumen has been used as a cement-like binder to seal the Great Wall of China and the Hanging Gardens of Babylon.

During the Roman Empire, bitumen was called "Bitumen Iudaicum, Judenpech". In 100 BC, the Roman avenue of Pompeii used asphalt to fill the joints and paint the outer layer.

Asphalt medieval

The Roman Empire declined and the medieval period began. During this time, asphalt lost its former glory. The accumulated experience of using asphalt in the past thousand years is almost lost, and it was not until the eighteenth century that people began to learn to use asphalt again. In 1000 AD, the Arabs began to extract bitumen from natural asphalt (Naturasphalt). The method is to heat the natural asphalt (Naturasphalt) until the bitumen (Bitumen) precipitates out of it.

Unlike building materials, bitumen was used for medicinal purposes in the Inca Empire in Central and South America in the 15th century. On March 22, 1595, Walter Raleigh discovered a natural asphalt lake on Trinidad during his expedition. To this day, people are still building roads with this kind of asphalt that emerges from the ground.

Modern asphalt

On the cover of a doctoral dissertation written by Eirini d'Eyriny in 1721, in 1712, the Greek doctor Eirini d'Eyriny discovered a huge amount of bitumen in Val de Travers, Switzerland. At first he was only interested in the medical use of asphalt. However, due to the excellent characteristics of asphalt as an engineering material, he eventually wrote his dissertation "Dissertation sur L'Asphalte ov Ciment Naturel" in 1721 and began to lay the foundation for the research of modern asphalt technology. For the next three hundred years (1712-1986), I don't know how much asphalt was mined through the labyrinth-like complex of mine tunnels in Val de Travers with a total length of more than 100 kilometers, and was sold to all over the world.

In the following years, the colorful use of asphalt was extended to the sealing of the roof waterproof layer. At that time, it was expensive to reinforce the pavement with asphalt, so that only roads dedicated to the rich could use asphalt to strengthen the surface. Asphalt was first used on bridges as an asphalt pavement installation on a wooden bridge in Sunderland.

In 1810, the asphalt matte pavement was first used in Lyon. Ten years later, the precursor of modern asphalt linoleum was developed and successfully used in Genoa. Based on extensive attempts, in 1837, the asphalt process proved to be applicable to highway engineering. In 1839, a method was found in Vienna, the capital of Austria, for reusing asphalt.

The first asphalted road appeared in Hamburg in Prussia in 1838. In 1851, a 78-meter-long section of the road from Travers to Paris was covered with asphalt. Just 20 years later, Paris was almost completely covered with asphalt, and soon afterwards the situation spread to almost all major European cities.

Later, the tough asphalt martyl grease was invented; in Innsbruck, Austria, in 1842, the pouring asphalt was invented and it was successfully used in road engineering soon after. Based on asphalt's properties similar to concrete, the concept of asphalt concrete was proposed by Léon Malo in 1853. In order to obtain a sufficient compression ratio, people began to compress asphalt concrete by roller compaction in 1876.

At the beginning of the 20th century, as the price of engineering materials continued to fall, asphalt showed more significance. In 1907, the first asphalt mixture components were put into use in the United States. In 1914, in order to obtain a better refractive index, people first saw the racing lanes on asphalt roads in Berlin.

Immediately following the application of asphalt in road engineering, in 1923, asphalt was used to seal dams. In order to speed up construction progress and improve components, the first road completion acceptance test was conducted in California, the United States in 1924. To determine the quality of building materials, many testing procedures have been developed over the next few years. These procedures are still effective today in the research, design and construction of traffic engineering. In 1936, Ring und Kugel-Versuch was invented, Brechpunkt nach Fraa & szlig was invented a year later, and Marshall-Test was invented in 1941.

With special additives, it has been possible to perform asphalt construction at low temperatures since 1950 (known as cold asphalt). In order to determine the appropriate thickness of the asphalt structure, in 1959, an interference-free method using isotopes was developed in Austria and successfully verified.

In order to bring the airport's runways into service as soon as possible, a dry asphalt construction process appeared in the United Kingdom in 1963. Not long after, in 1968, for the first time, martini asphalt was applied. Asphalt recycling began to be practiced in the United States in the 1970s. For better sealing effect, 1979 began to use bitumen in garbage dumps.

Asphalt category

Asphalt can be divided into three types: coal coke asphalt, petroleum asphalt and natural asphalt:

Asphalt coal coke pitch

Coal tar pitch is a by-product of coking, that is, the black substance remaining in the distillation kettle after tar distillation. It differs from refined tar only in physical properties, and there is no obvious limit. The general division method is to specify that the softening point below 26.7 ° C (cubic method) is tar, and that above 26.7 ° C is asphalt. Coal coke pitch mainly contains anthracene, phenanthrene, and rhenium which are difficult to volatilize. These substances are toxic, and the properties of coal tar pitch are different due to the content of these ingredients. The change of temperature has a great influence on coal coke pitch, it is easy to crack in winter and soften in summer. There is a special odor when heated; after heating to 260 ° C for 5 hours, its components such as anthracene, phenanthrene, and fluorene will volatilize.

Bitumen petroleum pitch

Petroleum pitch is a residue after distillation of crude oil. Depending on the degree of refining, it becomes liquid, semi-solid or solid at room temperature. Petroleum pitch is black and shiny with high temperature sensitivity. Because it was distilled to more than 400 ° C in the production process, it contains very little volatile components, but there may still be high-molecular hydrocarbons that have not been volatilized. These substances are more or less harmful to human health.

Asphalt natural bitumen

Natural asphalt is stored underground, and some form mineral deposits or accumulate on the crust surface. Most of this asphalt has undergone natural evaporation and oxidation, and generally does not contain any toxins.

Asphalt materials are divided into two categories, ground asphalt and tar asphalt. Asphalt is divided into natural asphalt and petroleum asphalt. Natural asphalt is the residue of petroleum exuding the surface after long-term exposure and evaporation. Petroleum asphalt is a product obtained by refining the residue of refined petroleum and processing it through appropriate processes. . The tar pitch is a product obtained by reprocessing the tar obtained by retorting organic matter such as coal and wood. Most of the bitumen used in the project is petroleum pitch. Petroleum pitch is a complex mixture of hydrocarbons and their non-metallic derivatives. Generally, the flash point of asphalt is between 240 ° C and 330 ° C, and the flash point is about 3 ° C to 6 ° C higher than the flash point. Therefore, the construction temperature should be controlled below the flash point.

Asphalt technical index

density

Mass of asphalt sample per unit volume at specified temperature, in t / t.

Relative density

At the specified temperature, the ratio of the mass of asphalt to the mass of water of the same volume.

Penetration

At a specified temperature and time, a standard needle of a certain quality is added to penetrate the depth of the asphalt sample vertically, expressed as 0.1mm.

Penetration index

A temperature-sensitive index of bituminous binder, which reflects the degree of change in penetration with temperature. The penetration with different temperatures can be calculated according to prescribed methods.

Ductility

The length of the asphalt sample in a predetermined form is stretched to a breaking speed at a certain speed at a predetermined temperature, and is expressed in cm.

Softening Point

The asphalt sample is placed in a metal ring of a predetermined size, a metal steel ball of a predetermined size and quality is placed on it, placed in water or glycerin, heated at a specified speed, and the temperature at which the steel ball sinks to a specified distance, expressed in ° C .

Solubility

The content of the solubles in the asphalt sample in the specified solvent is expressed as a mass percentage.

Evaporation loss

The mass loss of the asphalt sample in a sample dish with an inner diameter of 55mm and a depth of 35mm after heating and holding at 163 ° C for 5 hours is expressed as a percentage.

Flash point

The gas evaporated when the asphalt sample is heated in the specified sample container at the specified heating rate is contacted with the test flame in the prescribed method. The temperature of the sample when the first instant flash occurs is expressed in ° C. The sample holder is a Cleveland Open Cup (COC) for viscous asphalt, and a Tiger Open Cup (TOC) for liquid asphalt.

Fras crispies

The temperature of the asphalt sample film coated on the metal sheet when it cracks due to cooling and bending under specified conditions is expressed in ° C.

Viscosity

A measure of the resistance or internal resistance formed when an asphalt sample flows under specified conditions, also called viscosity.

Asphalt main products

Bitumen petroleum pitch

Petroleum pitch is a product of crude oil processing. It is a black or dark brown viscous liquid, semi-solid or solid at normal temperature. It mainly contains chloroform-soluble hydrocarbons and non-hydrocarbon derivatives. Its properties and composition Varies with crude oil source and production method. The main components of petroleum pitch are oil, resin and asphaltene. It also contains 2% ~ 3% pitch carbon and carbon-like substances, and also contains wax. Oil and resin in asphalt can wet asphaltenes. The structure of asphalt is based on asphaltenes, which absorbs some resins and oils to form micelles.

Product performance

Petroleum pitch is black and shiny with high temperature sensitivity. Petroleum asphalt can be classified according to the following systems:

production method

(1) Distillation method: Crude crude oil is frequently pressure distilled to separate gasoline, kerosene, diesel and other light fractions, and then reduced pressure distillation (residual pressure 10 ~ 100mmHg) is used to separate the reduced pressure oil. The remaining residues meet the specifications of road asphalt. At that time, asphalt products can be directly produced. The obtained asphalt is also called straight run asphalt, which is the main method for producing road asphalt.

(2) Solvent precipitation method: The non-polar low-molecular-weight alkane solvent has different solubility for each component in the vacuum residue. The difference in solubility can be used to achieve component separation, so it can be removed from the vacuum residue. The components with unfavorable properties of bitumen produce bitumen products that meet the specifications. This is the solvent precipitation method.

(3) Oxidation method: In a certain range of high temperature, air is blown into the vacuum residue or deoiled asphalt to change its composition and performance. The product obtained is called oxidized asphalt. Under the action of high temperature and air blowing, the vacuum residue will evaporate and evaporate. At the same time, a series of reactions such as dehydrogenation, oxidation, polymerization and condensation will occur. This is a very complicated comprehensive reaction process in which multiple components interact with each other, and not only the oxidation reaction occurs, but it is conventionally called oxidation method and oxidized asphalt, and also known as air blowing method and air blowing asphalt.

(4) Tuning method: Tuning method to produce bitumen originally refers to re-blending the 4 components of the same crude oil that make up the bitumen according to the required quality requirements. The resulting product is called synthetic asphalt or reconstituted asphalt. With the development of process technology, the source of blending components has been expanded. For example, residues or components from primary and secondary processing of the same crude oil or different crude oils, and various industrial waste oils can be used as blending components, which reduces the dependence on the choice of oil source in asphalt production. With the increasing shortage of crude oil suitable for the manufacture of bitumen, the flexibility and economy shown by the adjustment method are being increasingly valued and widely used.

(5) Emulsification method: The surface tension of asphalt and water is very different, and they will not be miscible with each other at normal temperature or high temperature. However, when the asphalt is subjected to mechanical actions such as high-speed centrifugation, shearing, and heavy impact, it is made into particles with a particle size of 0.1 to 5 microns and dispersed in an aqueous medium containing a surfactant (emulsifier-stabilizer). The agent can be directionally adsorbed on the surface of asphalt particles, thereby reducing the interfacial tension between water and asphalt, so that the asphalt particles can form a stable dispersion system in water, which is an oil-in-water emulsion. This dispersion system is dark brown, pitch is the dispersed phase, water is the continuous phase, and has good fluidity at room temperature. In a sense, emulsified bitumen is used to "dilute" bitumen with water, thereby improving the fluidity of the bitumen.

(6) Modified asphalt: Many changes have taken place in modern highways and roads: the traffic flow and driving frequency have increased dramatically, the axle weight of freight cars has continued to increase, and unidirectional driving in separate lanes has generally been implemented, requiring further improvement of road surface fluidity resistance, that is, high temperature The ability to resist rutting; improve flexibility and elasticity, that is, the ability to resist cracking at low temperatures; improve wear resistance and extend service life. Modern buildings generally use long-span prestressed roofing panels, which require roofing waterproof materials to adapt to large displacements, be more resistant to severe high and low temperature climate conditions, have better durability, have self-adhesion, facilitate construction, and reduce maintenance workload. These changes in the use environment pose severe challenges to the performance of petroleum asphalt. The modification of petroleum pitch to make it adapt to the above-mentioned severe use requirements has aroused people's attention. After decades of research and development, a wide variety of modified road asphalt, waterproofing membranes and coatings have appeared, showing a certain engineering practical effect. However, in view of the fact that the price of modified materials is usually 2 to 7 times higher than that of ordinary petroleum asphalt, users have not yet fully grasped the material engineering performance, and the output of modified asphalt has grown slowly. Modified road asphalt is mainly used for pavement applications in special occasions such as airport runways, waterproof bridge decks, parking lots, sports fields, heavy traffic pavements, intersections and road turns. The application of modified asphalt to the maintenance and reinforcement of highway networks in Europe has greatly promoted the universal application of modified road asphalt. Modified asphalt waterproofing membranes and coatings are mainly used for waterproofing projects in high-end buildings. With the progress of science and technology and the development of economic construction, it will further promote the development of varieties of modified asphalt and the development of production technology. The type and preparation technology of modified asphalt depends on the type of modifier, the amount added, and the composition and properties of matrix asphalt (ie, raw asphalt). Due to the wide variety of modifiers and their different forms, in order to form a uniform engineering and practical material with petroleum asphalt, various types of modifiers have been evaluated over the years, and corresponding formulas and preparation methods have been developed, but most Modified bitumen that has been used in engineering is a patented technology and patented product.

The main purpose

The main uses are as infrastructure materials, raw materials and fuels, and are used in various sectors such as transportation (roads, railways, aviation, etc.), construction, agriculture, water conservancy engineering, industry (extracting industry, manufacturing), and civil.

Packaging and storage

Asphalt may need to be stored in storage tanks during production and use. If treated properly, the asphalt can be repeatedly heated to maintain it at a relatively high temperature for a long time without serious damage to its performance. However, if it is exposed to oxygen, light, and overheating, it will cause the hardening of the asphalt. The most significant sign is that the softening point of the asphalt increases, the penetration degree decreases, and the ductility becomes worse, which results in loss of the performance of the asphalt

Heating output

Asphalt is stored in large storage tanks. When the output is used, the asphalt in the storage tank needs to be heated to improve the fluidity of the asphalt before it can be output smoothly and quickly. The heat source required for heating output is generally heat transfer oil. According to the Petrochemical Technology Promotion Center, the traditional heating methods have the following disadvantages:

1. The heating process is uneconomical. When only a small amount of asphalt needs to be poured out, the entire asphalt in the tank must also be heated. The amount of heated asphalt is several times the amount used this time, making a large amount of heat-conducting oil useless.

2. The temperature of the asphalt in each part of the tank is uneven. The temperature of the asphalt near the heater is higher, and the temperature of the asphalt far from the heater is lower, which seriously affects the fluidity of the oil.

3. Affect the asphalt quality. The asphalt in the tank is repeatedly heated, and a large number of fine decomposition products are generated during the heating process, which has a certain effect on the chromaticity quality of the asphalt and increases the cost of post-processing.

Local heating technology: After the heat-conducting oil enters the "local rapid heater", the asphalt in the asphalt tank is locally and quickly heated. How much asphalt is needed and how much asphalt is heated. The whole tank is not required and is repeatedly heated. While saving energy, the asphalt output is more rapid.

Asphalt rock asphalt

Asphalt pavement flow deformation is the most common asphalt pavement damage phenomenon in the world. According to statistics, about 80% of road surface maintenance statistics are due to deformation and damage caused by rutting. Through engineering practice, it has been found that modified asphalt added with rock asphalt has great advantages in terms of high temperature stability, and can well solve the problems of high-grade asphalt pavement road rut and early disease caused by heavy traffic, overload and overload.

Rock bitumen is a kind of bituminous substance that is produced under the combined action of heat, pressure, oxidation, catalyst, bacteria, etc. after the sedimentation and change of petroleum for hundreds of millions of years. Commonly used as a base asphalt modifier. The physical properties of rock asphalt are closer to "coal".

The proven natural rock and asphalt mineral resources in China are mainly distributed in Xinjiang, Qinghai, and Qingchuan, Sichuan. Qingchuanyan Asphalt Mine is distributed in Longmenshan area in northern Sichuan, which has the reputation of the country of Tianfu in China. The preliminary proved reserves are more than 3 million tons and the prospective reserves are 10 million tons. Reserves rank first in the country. The natural rock asphalt in northern Sichuan is composed of asphaltenes with a molecular weight of up to 10,000. Its chemical composition is 81.7% carbon, 7.5% hydrogen, 2.3% oxygen, 1.95% nitrogen, 4.4% sulfur, 1.1% aluminum, and 0.18% silicon. And other metals 0.87%. Among them, the content of carbon, hydrogen, oxygen, nitrogen, and sulfur is high, and almost every asphaltene macromolecule contains the polar functional group of the above elements, which causes it to have a very strong adsorption force on the surface of the rock.

Research results of domestic super asphalt

On May 25, 2014, the Chinese army conducted a test flight of the third-generation fighter aircraft on the Zhengmin Expressway for the first time. Military expert Sun Xiaowei of the Yangtze Evening News explained that the requirements of the runways on highways for aircraft take-off and landing are very strict, which is different from the standard for laying general highways. One of the key points is the "material" of this expressway. The top of Zhengmin Expressway is paved with a special layer of improved asphalt concrete. The reporter learned from an interview with Southeast University yesterday that this kind of "super asphalt" resistant to 300 and minus 30 was developed by Southeast University and Jurong Ningwu Technology Development Company.

"Super" Asphalt

Resistant to 300 high temperature, acid and alkali resistant and flexible

"The Zhengmin Expressway (Zhengzhou to Minquan) is an important communication channel in the highway network of Henan Province. The entire line adopts the two-way four-lane expressway technology standard. In 2008, the construction of the Zhengmin Expressway started with Zhang Zhanjun, a postdoctoral fellow of Southeast University as the general Responsible. The domestically produced 'super asphalt' used for laying this high-speed highway was developed by Jiangsu. "Researcher Zhu Jianzhu, assistant to the president of Southeast University, told reporters that this asphalt is called" epoxy asphalt ".

Unlike common bitumen, epoxy bitumen is made by adding epoxy resin to the bitumen. After reacting with the curing agent, the bitumen has high strength and toughness, and has little deformation at high and low temperatures. This material looks simple, as long as the asphalt and epoxy are mixed in a certain ratio. However, it is more difficult to get the right ratio of materials than to climb the sky. Scientific research is almost in a blank. "Just like human blood types, blood transfusions need to be matched. Asphalt and epoxy resin are obviously not compatible with each other. It is difficult here.

How old is this epoxy asphalt independently developed by Jiangsu? Zhu Jianshe introduced that in the repeated laboratory, the domestic epoxy asphalt is kept at a high temperature of 300 ° C and a low temperature of minus 30 ° C without deformation. "The temperature of the jet gas when jet planes take off and land reaches 1000 ° C, which can instantly 'melt' ordinary Asphalt. "This kind of asphalt is also resistant to corrosion." We did experiments and soaked the epoxy asphalt in acid, alkali, and salt for more than a month, and took out almost no change. "Another characteristic of this asphalt is its toughness. "In the past, most of our roads were rigid. The cars drove up and down, and there was a lot of noise. The wheels and pavement were severely worn. The new asphalt has a certain elasticity, which provides cushioning force for heavy aircraft when taking off and landing. The aircraft is not easy to wear." The key point is that this material is water absorbing and can penetrate the stagnant water caused by rain and snow.

R & D road

American asphalt paved on the Second Yangtze River Bridge

However, before 2006, the manufacturing technology of this kind of high temperature, low temperature and pressure resistant environmental protection asphalt was monopolized by the United States, and technical blockade was implemented. In 2001, the team led by the academician of the Chinese Academy of Engineering and Professor Huang Wei of Southeast University used the American "epoxy asphalt" when laying the Yangtze River Second Bridge. If ordinary asphalt is used for pavement, the bridge surface is easy to appear in the season with large temperature differences. The cracks and slippage will cause them to fall into the weird cycle of "repairing and repairing, repairing and repairing repeatedly". "But the price of epoxy asphalt in the United States is scary. One ton is more than RMB 70,000. After the second bridge is finished, Professor Huang Wei said that China must develop its own epoxy asphalt paving materials and complete sets of technology, a major national project. The core technology of construction must be in the hands of our Chinese! "

In 2001, Southeast University established the "New Epoxy Asphalt Manufacturing Equipment and Engineering Application Project Team", with Professor Huang Wei as the team leader, and Zhu Jianyan, a researcher who was the main person in charge, and chose Jurong Ningwu to carry out industry-university-research cooperation. "Professors from the three colleges of Transportation College, School of Chemistry and Chemical Engineering, and School of Automation of Southeast University and technicians of Ningwu Technology worked together for more than 6 years and finally mastered the manufacturing method of this special asphalt." One ton, our price is only half of it, more than 30,000. " ^[3]

Main characteristics of asphalt

Bitumen is very viscous but fluid. In April 2014, the world's longest-lasting experiment finally came to fruition, but the Australian physicist Maystone, who has been witnessing this experiment for more than 50 years, has passed away at this time for 8 months. The professor also missed the test results waiting for decades. ^[4]

In the 1920s, in order to show students that solids can also flow like liquids, Parnell, a professor of physics at the University of Queensland, Australia, conducted an asphalt drip test. Asphalt has two forms of solid and liquid under different conditions. It is a viscous material commonly used for waterproofing. The viscosity is 230 billion times that of water. The solid can resist the impact of the hammer without deformation. But a funnel can flow solid asphalt. ^[4]

In the experiment, the researchers put the asphalt into a glass funnel, and through the squeeze, the solidified asphalt would also flow down like a liquid, but the process was very slow. How slow is the asphalt flowing? Due to plate drift, the mainland of Australia moves about 6 cm northward each year, and the speed of asphalt solidification flow is 10 times slower than the movement of the earth plate. ^[4]

Physicist Maystone took over the custody work after Parnell's death, after which five drops of asphalt had been dropped. Maystone could have witnessed the longest-running experiment in the world 3 times, but God made people lose, and Maystone missed three ephemeral dripping moments and failed to see it until his death. Waiting for decades of experimental results. ^[4]

It is reported that in 1977, Maystone waited for the weekend when the asphalt was about to drip, but the asphalt dropped when he was exhausted to return home. In 1988, a drop of asphalt was almost dripping, and Maystone missed this rare moment again just 5 minutes after leaving the room for a cup of coffee. In 2000, in order to completely record the moment of asphalt dripping, Maystone installed a webcam so that even when he was far away in the UK, he could see and record the moment of asphalt dripping. However, a tropical storm caused a power outage of 20 minutes at that time, and when power was restored, Maystone had waited more than 10 years for the asphalt to have slipped. In 2014, the ninth drop of asphalt finally dripped again, but Professor Maystone never saw the moment it fell. In August 2013, Professor Maystone died of a stroke at the age of 78. ^[4]

After Professor Maystone's death, the experimental device was kept by White of Queensland University. White said the experiment could last at least another 80 years. At the rate of 2014, the next drop of asphalt will drip in 2027. It is reported that this experiment was recognized by the Guinness Book of Records as the longest-lasting experiment in the world, and it also won the "Ig Nobel Prize" in 2005-"research is to make you people laugh And think ". ^[4]

Major hazards of asphalt

Asphalt is a brown-black organic gelatinous substance, including four types: natural asphalt, petroleum asphalt, shale asphalt, and coal tar asphalt. The main components are asphaltenes and resins, followed by high-boiling mineral oil and a small amount of oxygen, sulfur and chlorine compounds. Glossy, liquid, semi-solid or solid state, brittle at low temperature, good adhesion and anti-corrosion performance. If your clothes are accidentally stained with asphalt, wash them with dilute sodium hydroxide.

Among the four kinds of asphalt, coal tar pitch is the most harmful. In the production of electrode baking furnace, a large amount of bitumen smoke is discharged. As asphalt contains fluorescent substances, which contain carcinogens 3,4 benzopyrene as high as 2.5% to 3.5%, it will volatilize with the smoke during high temperature treatment. Asphalt smoke is a yellow gas in which fine particles of tar are tested. It was determined that the asphalt flue gas discharged from the electrode baking furnace contained 3,4 benzopyrene at 1.3-2 mg / m3.

Asphalt smoke and dust can cause poisoning through the respiratory tract and contaminated skin, causing symptoms such as dermatitis, blurred vision, conjunctivitis, chest tightness, abdominal disease, palpitations, and headaches. Scientific tests have proven that 3,4 benzopyrene contained in asphalt and bitumen smoke is the main cause of skin cancer, lung cancer, stomach cancer and esophageal cancer.

Living in asphalt-contaminated air can easily lead to a decline in immunity.

The main components of asphalt and its smoke are phenols, compounds, anthracene, naphthalene, pyridine, etc., which are irritating to the skin and mucous membranes. Applying 30% coal tar pitch toluene solution for 3 times, localized inflammation and hyperkeratosis after local inflammation Cleft.

Asphalt and its anthracene, phenanthrene and pyridine are phototoxic substances, which can cause photochemical reactions under the action of ultraviolet rays. The photochemical reaction caused by asphalt is a photochemical reaction of asphalt under aerobic conditions through the action of light energy, which reflects the damage of cells caused by the generated free radicals and peroxides, so it is a non-immune disease.

Animals reproduced asphalt cancer. China has also used mouse skin test to see that asphalt can cause skin cancer. Most are phosphorous epithelial cancers, and a few are keratinoma. It is generally believed that kerosene asphalt has the strongest carcinogenicity, natural asphalt is not carcinogenic, and opinions on the carcinogenicity of petroleum asphalt are still inconsistent.

The impact of coal tar pitch coating on animal weight gain is more significant than that of petroleum pitch, and the skin coating of coal tar pitch is more harmful to animals than the smoke inhalation. It is suggested that coal char pitch has a certain systemic effect on animals, and the degree of effect is related to the absorption pathway.

Skin damage

1. Solar dermatitis is usually caused by exposure to asphalt dust or smoke and exposure to sunlight.

Workers laying asphalt road The onset of the disease can occur within a few minutes to 1-2 days (mostly several hours) after sun exposure. Skin lesions are limited to the exposed parts of the face and back of the neck, especially the eyelids and cheeks. The skin lesions are sunburn-type with clear-cut red and red spots, often accompanied by edema, and severe blisters, bullae, and even erosion and exudation. The skin lesions reached a peak within 1-2 days, and generally stopped contacting for 3-5 days, and the skin lesions subsided quickly, with mild bran-like scales attached locally, often with temporary mild pigmentation. Conscious burning, individual mild itching.

2. Melanosis is usually symmetrically distributed on the exposed areas of the face and neck, and also spreads on the forearm. It is particularly common in the eyes, the temporal area, the forehead hairline and the inner corners, the paranasal cheeks and the mouth area. Skin lesions are mostly flaky, darker in color, brown-dark brown-brown-black, and sometimes slightly maroon or lavender. The size and shape are different, and the edges are mostly blurred. The pigmentation of the forearm is usually centered on the pores, and the affected pores are slightly keratinized; sometimes the brownish grayish-purple pigmentation spots are intertwined with the normal skin and become cloud-like. Onset often has a history of repeated episodes of asphalt phototoxic dermatitis, and is often accompanied by asphalt acne. The disease is a chronic process. Every day the sun worsens the condition. Disengagement is expected to improve and heal.

3 Occupational acne caused by acne pitch is mainly manifested by blackheads, broken hairs, and folliculitis. The disease is prevalent in direct contact

Sites, such as the face, back of fingers, back of hands, and forearms, often also spread to parts of garments contaminated by asphalt, such as thighs, and occasionally on the trunk. Blackheads are black spots in enlarged pores, often with small white patches. Blackheads caused by asphalt are generally larger than those caused by chloride, and their distribution is also scattered. They are mainly located on the face, especially the temporal, eyebrow, and sides of the nose. Eyelids and auricles can also be affected. Inflammatory red papules of the hair follicle are follicular papules, with yellow-white pustules at the top, which in severe cases develop into palate, induration, and scarring; often scattered on the face and forearm. The hairs of the palate are broken and thickened, and the local pores are often dilated and slightly keratized, mainly distributed in the first dorsal digit and the forearm radial extension. The onset of this disease is not restricted by age. Conscious symptoms are absent, sometimes with a sense of dryness, and there is pain when folliculitis occurs.

4 Verrucous vegetation occurs on the back of the hands, wrists, and face, and can spread to the scrotum. Similar to flat wart, with skin tone--hazel--brown flat

asphalt Pimples, needle caps or mung beans, round or irregular, rough or smooth surface, clear state. Scattered or densely distributed.

No conscious symptoms or slight itching. Generally, the longer the working age, the higher the incidence and the more skin lesions. Verrucous can subside naturally. May evolve into skin cancer.

5. Burns are mostly caused by accidents such as splashing and falling. High-temperature liquid asphalt causes thermal burns to the skin. The clinical manifestations are similar to general thermal burns. The skin surface can be covered with black asphalt, which adheres tightly to the wound surface and is difficult to remove.

Eye, nose, and throat symptoms

The damage to the eyes caused by asphalt dust and smoke is mainly conjunctivitis, sometimes accompanied by superficial punctate keratitis, and pterygium of a longer working age occupies a certain proportion. Nasopharynx often has a dry, burning sensation, which can also cause rhinitis and pharyngitis.

Systemic symptoms

After smelling the smell of asphalt, dizziness, bloating, headache, chest tightness, fatigue, nausea or cough, palpitations, tinnitus and other discomfort may occur, especially when operating under the hot sun. Disengagement (after work hours) often resolves quickly. In severe cases (such as severe phototoxic dermatitis), fever can be associated.