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Analysis on the causes of early failure of asphalt concrete pavement and its prevention measures

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Analysis on the Causes of Early Damage to Asphalt Concrete Pavement and Preventive Measures

(Inner Mongolia Road and Bridge Co., Ltd., Hohhot, Inner Mongolia 0 1 0 0 5 1) 【Abstract】 With the widespread use of asphalt pavement structures in expressways, the problems of durability and early damage of pavement structures have become increasingly prominent. This article mainly analyzes asphalt concrete

Causes of early pavement damage and the measures to be taken.

[Keywords] Causes of Asphalt Concrete Pavement

1 Analysis of causes of early damage to pavement and measures taken 1.1 Early damage to pavement caused by poor raw materials

Made provisions. One

② Optimize the design of the mixture. The proper design of the mixture is important to eliminate segregation. Generally speaking, the mixture designed uniformly according to continuous gradation is easy to eliminate segregation during construction, and the various sizes of crushed stones used in the asphalt pavement of highways in China at present are strictly based on the construction process to avoid multiple on the market. For the crushed stone yard, because there are few large-scale stone yards in China, most of the stone-graded mixtures are prone to segregation during construction to avoid segregation. From the stone yard opened by the self-employed, the scale is small, the equipment is backward, and the quality control is lacking. ③ Pay attention to the loading and unloading of the dump truck. The dump truck should be divided into three different means when receiving the materials. The stone crusher is usually a single jaw crusher, and some configurations receive the material. The first time is the front of the car, the second time is the tail, and the third time is the middle. There can be hammer or cone crushers, but the specifications are different. Some sieving equipment used vibrates to eliminate segregation during charging. When unloading into the paver, the mixture should be unloaded as a whole without moving the sieve, and some use a cylindrical sieve. Some of the screens used were purchased from professional production plants, but the specifications were different. Therefore, the floor of the cabin needed a good opening and closing state and was coated with lubricant to make it full, some were self-made, and some were still used after being broken. In recent years, as the expressway has gradually unloaded people from stones. The requirements are getting higher and higher. Some stone mills have purchased impact rock mills, but because of this type of product, the mixture is unloaded at the same time. ④ The stacking site of the asphalt concrete mixing site should be hardened, keep the aggregate clean, prevent low output, and have high energy consumption and high costs. Some individual bosses take out stones during sampling to cause uneven mixing. Good-grained high-quality crushed stones. Once the order is made, especially when the stone is at its peak, muddy contaminated aggregates on the rainy day will be collected. ⑤ The aggregates in the mixing site should be stacked separately and reliable isolation measures should be taken. To avoid mixing the crushed stones produced by other types of stone rolling mills and sending them to the construction site, the phenomenon of segregation caused by the clutter during the construction period is avoided. Urgent tasks, some construction units have no choice but to accept

Affected by this} Kunhe Stone. Aggregates of different specifications mentioned above} ⑥ Various fine aggregates should be covered with awnings to prevent rain. Prevent the fine aggregate from being exposed to rain and other factors causing uneven specifications of the pavement material. The needle-like shape exceeds the standard. The produced drain is damp. Avoid the damp fine aggregate from dumping into the mixer hopper and the flow will be affected. Poor uniformity of the mixture causes early disease on various pavements. The mixing ratio is inaccurate, causing local segregation. In addition, after the scaffolding, the measures for drying the fine aggregate due to drying are as follows: ① When selecting a stone manufacturer, try to use a large scale. A well-equipped dry cylinder can greatly reduce energy consumption and save diesel oil than a wet aggregate. Manufacturers. ② The high-quality stone produced by the large stone factory invested by the owner is adopted. 1.4 Early pavement damage caused by raining construction ③ The construction unit invests in purchasing counter-rolling equipment for secondary crushing or direct investment

Although the operation instruction clearly stipulates that construction on rainy days is strictly prohibited, it is used in the stone yard during actual construction, and the funds for the purchase of equipment will be used to offset the funds afterwards. ④ Strengthening the routine will encounter the asphalt mixture has not yet been paved due to sudden changes in weather due to sudden rainfall. In the south, the responsibility of the material staff must not be limited to quality and quality. Stones that do not meet the specifications and exceed severe standards often encounter such bad conditions. In the weather, because there is still black material in the storage bin and the transportation vehicle, one vehicle must be rejected. The cost is about 5,000 to 6,000 yuan. In order to reduce losses, speed up the paving speed before it rains. When the 1.2 roadbed is not compact enough to cause early damage to the pavement, the heavy rain will continue to rush when the light rain has begun. At this time, due to the heat, during the construction of the roadbed, the compaction degree is not well controlled, and the horizontal unevenness is likely to cause the temperature of the hot material to drop sharply. The material that affects the driving comfort absorbs a large amount of heat and turns into steam after encountering water. The porosity increases after warm rolling, causing early damage to the surface layer. To avoid the above situation, we must first be safe. To avoid early damage to the pavement due to insufficient compaction of the roadbed, it is necessary to know the weather forecast at any time and arrange the construction time reasonably. The communication between the front and back field is to pay attention to its compactness. When backfilling the platform, the backfill materials must be strict. Control the particle size, the front yard of the layered mill immediately notices the rear yard to stop mixing when it finds the rain. The thickness of all transport vehicles should be controlled at 15 cm, and it is very important to use large rollers to ensure compaction. Covering canvas must be provided during construction, one for insulation and two for protection from rain. You must stop if it starts to rain. Excavation of culverts and box tunnels should expand their cross-sections. Slopes should be dug into steps. If it rains for a long time in layered backfilling, the mixture in the vehicle should be discarded when it falls below 1 1 0 "C. Press and excavate The width of the roller can accommodate the width of the roller of the roller. For the pipe paving formed by the excavation of buried pipelines, so as to avoid

When the temperature of the mixture exceeds the bottom, the compaction cannot reach the specified compaction degree and cause rework. The loss is even more backfilling. The backfill quality can be ensured by using fly ash gravel or plain backfilling. Big. 1.3 Severe segregation caused early pavement damage. Improper construction caused segregation of pavement surface layer can cause early pavement damage, such as network cracks, deformations and potholes caused by isolated water damage, local severe rutting, local flooding, lateral cracks. In many cases, the surface structure depth of the newly-paved asphalt surface layer is rough and thin, and the excellent initial smoothness of the road surface is rapidly deteriorated. When the mixture is segregated, coarse aggregate and fine aggregate are concentrated in certain positions of the paving layer, which makes the asphalt concrete uneven, the mix ratio gradation and the amount of asphalt do not match the design, resulting in local porosity and surface water. Enter the asphalt concrete surface layer. When the rain is sunny, if there are often wet spots on the road surface from the east to the west, it means that the local isolated rainwater at the wet spots has passed through the surface layer, and the place is evenly and densely in the sun. Dry, because the water has entered the deep layer at the wet spot, it cannot be dried in a short time and stay in the pores. Under the action of a large number of high-speed driving, the dynamic water pressure generated each time causes the asphalt to gradually peel off from the gravel surface, causing Early damage to the pavement. The measures to be taken are as follows: ① In the pavement operation of each layer of the road surface (including the base layer and the base layer), two pavers should be used.

1.5 Asphalt mixture pavement layering caused by pavement pollution In the organization of pavement construction, sub-strip filling, soil shoulder construction, protective engineering construction, installation of transportation facilities, and vehicles from various intersections along the line are driven on the road. On the completed pavement, these cross constructions interfere with each other and easily cause serious pollution. If the lower pavement is not cleaned during the construction of the upper pavement, and there is no spray of sticky oil or sprayed but not uniform, the upper and lower The layers failed to bond together to form a separation layer. Under the load of the vehicle, the shear force was the highest between the upper and lower layers, which caused the interface to fail to transfer shear forces, which caused rapid damage to the upper layer. It is characterized by the following

The top surface of the layer is smooth and smooth, and the upper layer forms a pit. Especially in the middle zone and the edge of the dirt road shoulder, soil pollution of the road is more serious, and it is easier to form the separation between the surface layers. To avoid pollution, we must first reduce cross-construction as much as possible. Before the construction of black pavement, we must complete the filling and greening of the sub-zone. The construction of the shoulder of the road, the construction of the protective works, and the installation of transportation facilities must be properly planned and a special Anti-pollution measures to reduce pollution. Sand that must be placed on the road ...

Clean up in time after use. It is strictly forbidden to mix the machine echelon directly on the pavement to ensure that all layers of the pavement are evenly spread. To avoid the paving in the past, it is easy to cause the stone materials to be supported by colored strips. Turn to page 1 4 6 for partial isolation. Common quality problems. Jiangsu, Zhejiang and other provinces have clearly stated in the construction guidance letter 2 0 1 3

Issue 1 of October 2016 Total Issue 1 7 Issue 1 43

Analysis on the causes of early failure of asphalt concrete pavement and its prevention measures

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