1. Q: What is the difference between different grades of bitumen?
A: The commonly used petroleum bitumen grades include AH-50, AH-70, AH-90, AH-110, AH-130. Different grades of bitumen have different softening points, e.g. AH-50 has a softening point between 45 and 55°C, while AH-200 has a softening point of only about 30°C. In general, the higher the grade, the higher the penetration of bitumen, the better its fluidity, suitable for areas with higher temperatures; the lower the grade, the harder the bitumen, suitable for areas with lower temperatures.
2. Q: How does the aging of bitumen affect its performance?
A: Bitumen may deteriorate after repeated heating or prolonged exposure to air. For the aged bitumen, the bitumenene content increases, the ductility and adhesion decreases, resulting in bitumen hardening and brittleness, which is prone to cracks and other problems, affecting the service life of roads.
3. Q: What is the production process for bitumen?
A: The main production processes for bitumen include distillation and oxidation, among others. Distillation is to separate the different fractions of crude oil to obtain bitumen products; oxidation is to oxidize the bitumen under certain temperature and oxygen conditions to improve the hardness and viscosity of the bitumen.
4. Q: How to control the quality during bitumen production?
A: During the production process, it is necessary to strictly control parameters such as the quality of raw materials, production temperature, and reaction time. Furthermore, the quality of the produced bitumen must be tested, including the testing of indicators such as the softening point, penetration, and ductility of the bitumen, in order to ensure that the quality of bitumen meets the standard requirements.
5. Q: What is the optimal temperature for asphalt pavement construction?
A: In general, the paving temperature of asphalt mixture should be above 130°C, the initial pressing temperature should not be lower than 120°C, and the final pressing temperature should not be lower than 70°C. However, the specific construction temperature needs to be adjusted based on factors such as the grade of asphalt and local temperature.
6. Q: How to ensure the compaction of asphalt pavement?
A: First of all, choose the appropriate rollers and compaction techniques, and compact according to the principle of light first then heavy, slow first then fast. Secondly, control the number of compaction cycles and speed to ensure that the asphalt mixture can be fully compacted. In addition, attention should be paid to the travel route of the rollers to avoid missed compaction or repeated compaction.
7. Q: What are the common diseases of asphalt pavement? How to handle?
A: Common diseases include cracks (including transverse cracking, longitudinal cracking, mesh cracking, etc.), potholes, raveling, lumps, depressions, shoving, and edge failure. For cracks, where the width is less than 2 mm, no treatment is required; where the width is greater than 2 mm and less than 4 mm, preventive maintenance may be carried out by adding a cover layer; where the width is greater than 4 mm and less than 10 mm, the joints should be expanded, cleared and then filled; where the width is more than 10 mm, grooves should be opened and filled for repair. For potholes, corresponding treatments are required based on the depth of potholes and the cause of their formation. For example, potholes on the surface layer can be repaired directly using an insulation vehicle or an asphalt repair vehicle. Where potholes are formed due to damaged base layers, repair the base layer first and then lay the surface layer.
8. Q: What are the measures for daily maintenance of asphalt pavement?
A: Daily maintenance measures include regular cleaning of pavement to keep it clean; timely handling road cracks, potholes and other diseases to prevent the disease expansion; strengthening the maintenance of the road drainage system to ensure smooth drainage; regularly inspecting the pavement to understand the road usage, etc..
9. Q: Which environmental pollutions may be caused during the production and construction of bitumen?
A: During the production process, pollutants such as waste gas, waste water and waste residue will be produced, wherein the waste gas mainly includes bitumen fume and volatile organic compounds, which cause pollution to the atmospheric environment; the waste water mainly contains pollutants such as petroleum and suspended matter, which may pollute the water body if directly discharged without any treatment; the waste residue is mainly the wastes generated during the production process. During the construction process, the mixing and paving of asphalt mixtures will also produce pollutants such as asphalt fume and dust.
10. Q: How to reduce environmental pollution in the asphalt industry?
A: During the production process, advanced production processes and equipment can be used to reduce the generation of pollutants; the waste gas, waste water and waste residue generated can be effectively treated and recycled. During the construction process, it is necessary to strengthen the management of the construction site, take measures such as sprinkling water to reduce dust, setting up fences, etc. to reduce dust emissions; collect and treat asphalt fumes to reduce the impact on the environment.
11. Q: What are the differences in asphalt pavement construction in different areas?
A: There are indeed significant differences in asphalt pavement construction in different areas, which are mainly due to geographical environment, climatic conditions, traffic flow and pavement design requirements etc.. First, the geographical environment directly affects the selection of construction materials and construction technologies. In mountainous areas or areas with complex terrain, asphalt pavement construction requires stronger skid resistance, wear resistance and stability to address challenges such as steep slopes and sharp turns. In plains or urban areas, more emphasis is placed on flatness and driving comfort. Secondly, climate is also a key consideration. In cold areas, asphalt mixtures with good low-temperature performance are required to prevent cracking in winter; while in hot and rainy areas, materials with strong water damage resistance to ensure smooth drainage on the pavement and reduce water damage. Furthermore, the bearing capacity and durability of the pavement depends on the traffic flow. For heavy traffic areas such as expressways and trunk roads, the thickness and strength of the pavement structure layer need to be increased during construction to meet the traffic needs of high-frequency and heavy-loaded vehicles. In addition, pavement design requirements will also have influence on the construction scheme. For example, in the event of asphalt renovation of a school playground, in addition to achieving basic traffic functions, the safety and comfort of students must also be considered. Therefore, there will be special requirements for material selection, color matching and anti-slip treatment.
12. Q: How is the noise reduction effect of asphalt pavement?
A: The noise reduction effect of asphalt pavement is very significant. Asphalt pavement has better sound absorption and shock absorption performance than other pavement materials due to its unique material structure and construction technology. It can effectively reduce the noise generated during vehicle traveling, and provide residents with a more peaceful living environment. Specifically, the noise reduction of asphalt pavement is mainly achieved through the following: first, the porosity and elasticity of its surface material can absorb and disperse the sound generated by the friction between the tire and the pavement; second, the compactness of asphalt mixtures reduces the reflection and propagation of sound inside the pavement; third, the optimization of the pavement design, such as reasonable slope and texture, may also play a certain role in suppressing noise.
13. Q: What ground preparations are required before paving asphalt pavement?
A: Ground preparations before laying asphalt pavement are crucial, as it is directly related to the quality and effect of subsequent constructions. The main preparation steps are described below: First, clearing and leveling. Before construction, the original ground must be thoroughly cleared, including removing weeds, gravel, soil and other debris to ensure that the ground is clean and free of debris. Additionally, use equipment such as forklifts or excavators to level the ground to ensure that the ground flatness meets the construction requirements. This step is the basis for ensuring that the asphalt pavement is evenly and smoothly laid. Second, foundation reinforcement and treatment. For areas with unstable foundations or weak layers, foundation reinforcement is required, for example, laying a gravel layer, grouting reinforcement, etc., to improve the bearing capacity and stability of the foundation. This is key to ensuring that asphalt pavement does not have problems such as sinking and cracking during long-term use.
Furthermore, laying the base material. After the ground is leveled and the foundation is reinforced, the base material, such as gravel, crushed stone, etc., needs to be laid and compacted through rollers to increase the stability of road. This step provides a solid foundation for laying the asphalt pavement. Finally, **inspection and measurement**. After laying the base material, detailed inspection and measurement are required to ensure that the flatness and slope of the ground meet the design requirements. Additionally, surveying and elevation measurement are carried out on the asphalt pavement to be paved, which provides accurate guidance for subsequent paving constructions.
14. Q: How long can the color of colored asphalt pavement last without fading?
A: The color retention time of colored asphalt pavement varies depending on many factors. However, in general, under the conditions of regular construction and reasonable maintenance, it can remain unfaded for several years. The specific retention time depends on the quality of the pigment used, the pavement material, the construction technology, the traffic flow and the climate.
15. Q: What are the main types of bitumen? What are the characteristics of each type?
A: There are mainly three types: natural bitumen, petroleum bitumen and coal tar pitch. Natural bitumen exists naturally in nature, with relatively stable properties, but low output; petroleum bitumen is extracted from petroleum and is the most widely used, whose properties can be adjusted through different processing techniques to meet different engineering requirements; coal tar pitch is a by-product of coking, with high viscosity and hardness, but relatively high content of harmful substances, so special attention should be paid to environmental protection and health issues when using such type.
16. Q: How to evaluate the performance of bitumen?
A: It can be evaluated based on indicators such as bitumen softening point, penetration and ductility. The softening point reflects the thermostability of bitumen. The higher the softening point, the less likely the bitumen is to soften and flow under high temperature. The penetration indicates the hardness of bitumen. The smaller the penetration, the harder the bitumen. The ductility reflects the flexibility of bitumen. The greater the ductility, the less likely the bitumen is to crack under low temperature.
17. Q: What types of asphalt mixing plants are there?
A: According to the production process, there are batch process and continuous process; according to the ways of transportation, there are mobile, semi-fixed and fixed types; according to the production capacity, there are small type (productivity below 40 t/h), medium type (productivity between 40–400 t/h) and large type (productivity above 400 t/h).
18. Q: What is the difference between batch asphalt mixing plant and continuous asphalt mixing plant?
A: Batch Asphalt Mixing Plant heats and dries aggregates and mixes the mixture periodically, mixing each pot separately with a certain time interval, which can better control the quality of mixture, and is suitable for producing high-quality asphalt mixtures. However, the production efficiency is relatively low. While in Continuous Asapht Mixing Plant, the heating and drying of aggregates and the mixing of mixtures are carried out continuously in a same drum. The production efficiency is high, but there are high requirements for the quality and gradation stability of raw materials, and the quality control of mixtures is relatively difficult.
19.Q: What is the main process flow of asphalt pavement construction?
A: It includes construction preparation (such as site clearing, material preparation, equipment debugging, etc.), base treatment (such as leveling and compacting of base), mixing, transportation, paving, rolling of asphalt mixtures and final maintenance.
20. Q: How to control quality during asphalt pavement construction?
A: Control the quality of raw materials to ensure that the grading of aggregates and the performance of asphalt meet requirements; strictly control the mixing temperature and mixing time of asphalt mixtures to ensure the mixture uniformity; during the paving and rolling process, control the paving speed, rolling cycles and rolling temperature to ensure the flatness and compaction of pavement.
21. Q: What are the common diseases of asphalt pavement? How to maintain?
A: Common diseases include cracks (including transverse cracking, longitudinal cracking, mesh cracking, etc.), ruts, potholes, bleeding, raveling, etc.. For cracks, crack filling and sealing or other methods can be used, depending on the width and depth; for severe ruts, milling and repaving are required; potholes need to be cleared of debris first and then filled with new asphalt mixture;bleeding can be treated by spreading aggregate chips or other methods; in the event of raveling, the raveled parts need to be removed before repaving asphalt mixtures.
22. Q: How to determine the maintenance schedule of asphalt pavement?
A: Regular pavement inspections, such as flatness inspection, crack inspection, rutting inspection, etc., can be performed to judge the condition of pavement based on the inspection results, so as to determine whether maintenance is required and the specific time and method of maintenance. Additionally, the maintenance schedule can also be comprehensively considered based on factors such as the service life of pavement and traffic volume.
23. Q: What is emulsified bitumen?
A: Emulsified bitumen is a liquid bitumen made by mixing bitumen with an emulsifier and water through mechanical stirring and chemical stabilization. This bitumen has low viscosity and good fluidity at room temperature, so that it can be used at room temperature and can be used with wet and cold stones. Emulsified bitumen mainly consists of bitumen, emulsifier, stabilizer and water.
24. Q: What is the cost of a 10 cm thick asphalt pavement?
A: The cost of a 10 cm thick asphalt pavement is approximately 115 yuan/m2. Such cost includes machinery cost, management fee, material cost and profit. Specifically, the material cost is about 1,020 yuan/m3, the machinery cost is 7 yuan/m2, and the management fee plus profit totals 6 yuan/m2.
25. Q: How many square meters can be paved with 1 ton of asphalt mixture?
A: How many square meters can be paved with 1 ton of asphalt mixture? This mainly depends on factors such as paving thickness, pavement design and type of asphalt mixture. In general, the density of asphalt is about 2.35 t/m3. If the paving thickness is 3 cm, one ton of asphalt mixture may pave approximately 14.2 m2 of pavement. But please note that this is only an estimate. For the actual paving area, the asphalt compacted pavement structure and other factors should also be considered. In specific construction, calculations and adjustments should be made according to design requirements and actual conditions.
26. Q: How to determine the optimal condition of asphalt mixture at first glance?
A: How to know the optimal condition of asphalt concrete at first glance? During the construction of asphalt roads, various problems are often encountered, such as displacement, difficulty in compaction, difficulty in finishing, and block and strip centrifugation. The asphalt mixture truck starts slowly, and the asphalt mixture is refined at 35–45 degrees before sliding down as a whole into the paver. The poor condition is that the mixture slides freely from top to bottom. In this state, block segregation, truck tail segregation, uneven pavement and poor flatness are prone to occur during paving. On-site management personnel are very important, especially when the first truck starts paving every morning. They must check the condition and notify the relevant laboratory personnel to make adjustments as soon as possible in case of any problems. Because asphalt is constructed continuously at 1.5–2 km per day. Therefore, on-site personnel must discover problems at first glance, and have the ability to solve problems, respond and make adjustments quickly so as to ensure the construction quality.
