What does overlay mean? In fact, this is a construction structure related to asphalt pavement. Ordinary asphalt pavement will appear after a period of use of flatness, waterproof, anti-skid problems, in order to improve the quality of use of the pavement, solve the problem of the amount, need to add a layer of fine stone thin asphalt surface layer on the original asphalt pavement, this layer of structure is called overlay.
At present, there are three types of covering surfaces that are more commonly used in ChinaFirst, the structure of the old concrete slab, the isolation layer and the asphalt concrete surface course; the second is to crack and stabilize the structure of the old cement concrete slab and the asphalt concrete surface layer; The third is the structure of the old concrete slab mixed with semi-rigid base and asphalt concrete surface layer.
Asphalt concrete surface courses are thick and thin, but thin layer overlays are more popular in comparison. Not only because the thin layer cover is more economical, but more importantly, the construction time is shorter and the process is less. Ultra-thin overlay technology has been introduced on the market, which is a new pavement construction method, which is an economical, fast and effective pavement preventive maintenance construction technology by laying a thin layer of asphalt mixture on the original pavement to improve the anti-slip and durability of the road. Ultra-thin overlay technology has many advantages:
1.Increase the depth of pavement structure, improve flatness, and enhance pavement slip resistanceUltra-thin overlay technology can significantly increase the construction depth of the pavement, making the pavement rougher, and thus enhancing the anti-skid performance of the pavement. At the same time, because the thickness of the ultra-thin overlay is only a few millimeters, it will not cause damage to the original pavement, so it can effectively improve the flatness of the pavement.
2.Repair light diseases, reduce noise, and extend service lifeUltra-thin overlay technology can effectively repair light diseases, such as minor cracks, potholes, etc., making the road surface smoother and more beautiful. In addition, due to the good compactness of the ultra-thin covering, it can effectively absorb the noise of the vehicle while driving and reduce noise pollution. In addition, the ultra-thin overlay technology is able to extend the life of the road because it reduces the erosion of water, salt and other chemicals, reducing the risk of road damage.
3.Reduced damage to existing pavement:The application of ultra-thin overlay technology can greatly reduce the damage to existing roads. Traditional pavement rehabilitation methods often require digging up the pavement and resurfacing with new materials, which leads to traffic congestion and long construction times. The ultra-thin overlay technology only needs to add a thin layer of asphalt mixture to the original pavement, and does not need to excavate and replace the original pavement structure, so the construction can be completed quickly and the impact on traffic can be minimized.
4.Low construction costs:Ultra-thin overlay technology is less costly than traditional pavement maintenance methods. Since there is no need for large-scale excavation and reconstruction work, the construction cost is relatively low. Moreover, due to the thinner thickness of the asphalt mixture, the amount used is also less, which further reduces the cost of materials. As a result, ultra-thin overlay technology can save individuals a lot of money in the long run.
Ultra-thin overlay technology has many advantages, which makes it widely used in highway and urban road construction. This technology is often used in the preventive maintenance and quality improvement of asphalt pavement, as well as to provide ultra-thin "white to black" technical means for cement concrete pavement, bridge deck and tunnel. However, it should be noted that the ultra-thin overlay process has extremely strict requirements for asphalt product adhesion, gravel particle size, mixture mixing and paving and rolling equipment technology, etc. This article briefly explains the selection criteria for raw materials.
The asphalt in the ultra-thin overlay asphalt mixture can be selected according to the engineering technical requirements 70 asphalt, modified asphalt, rubber asphalt, composite modified asphalt, etc.; The coarse and fine aggregates used should be kept clean, dry, rough and non-weathered, free of soil or impurities, and have little needle-like particle content, and basalt or diabase can be used; When the mineral powder is filled, the dry, clean and free mineral powder produced by the grinding of hydrophobic stone should be used; In order to improve the road performance of the mixture, it is usually chosen to add fiber stabilizers, and the ultra-thin asphalt mixture should be made of lignin fiber, polyester fiber, etc., and the mixing ratio of general lignin fiber should not be lower than 0 of the total amount of asphalt mixture3%, the amount of polyester fiber should not be less than 02%；The interlayer bonding of ultra-thin overlay asphalt pavement should use SBS modified high-viscosity emulsified asphalt as the adhesive layer oil. The mix design needs to follow the three stages of JTG F40 on the design of the target mix ratio, the production mix ratio and the verification of the test mix and paving to determine the ore gradation and the best oil-stone ratio.
In summary, ultra-thin overlay technology has been widely used worldwide as an efficient, environmentally friendly and economical pavement construction method. It not only solves many problems in the construction process of traditional asphalt concrete pavement, but also greatly improves the service life of the pavement, reduces environmental pollution, and has good social and economic benefits. However, the construction process of ultra-thin overlay needs to be further improved and promoted, so it still needs to be continuously explored.