The key factors to improve the performance and durability of Asphalt Pavement

The performance of asphalt concrete surface layer mainly refers to the smoothness, anti sliding and reducing noise. As everyone knows, the asphalt concrete surface layer structure, smooth degree and strength of each layer underlying the flatness, and uniformity of the surface layers of asphalt concrete (mixing uniformity, no aggregate segregation and temperature segregation and compaction uniformity), construction technology is advanced and strict on the extent of it little relationship with the quality and gradation of asphalt and aggregate. The anti sliding performance and anti noise performance of asphalt concrete surface layer are mainly determined by the quality of surface layer and aggregate gradation, which is not related to the quality of asphalt.

In order to make use of the excellent durability of asphalt concrete pavement, pavement in addition to have enough bearing capacity, the road will not produce structural damage, we must also solve the asphalt concrete surface layer itself may have some early damage, common early destruction has caused serious rutting, serious bleeding of asphalt concrete layer; asphalt concrete layer, especially the surface layer is easy to water, and lead to early water damage; serious low temperature cracks of the asphalt concrete surface layer, fatigue cracking of asphalt concrete layer (mainly for flexible pavement). Therefore, stronger resistance to permanent deformation at high temperature of asphalt concrete, the repeated action of asphalt concrete layer can withstand the heavy vehicle, not easy to produce serious rutting of asphalt concrete; aggregate ratio should be appropriate, to avoid bleeding; asphalt concrete layer compaction, low permeability of water and good uniformity, so that the water is not easy to penetrate and stay in a layer, in order to avoid early water damage.

In the long run, but also to reduce the serious temperature cracks (including corresponding cracks) and increase the fatigue life of asphalt concrete layer.

From the high temperature resistance to permanent deformation ability, the first thing is to use aggregate quality, followed by the need to form aggregate skeleton dense structure, under this premise, and then use the asphalt high temperature viscosity, high temperature can make the asphalt concrete has high resistance to permanent deformation. Therefore, ore quality and aggregate gradation are the most important factors.

From the oil, is the main problem of asphalt content and porosity of asphalt concrete. It can also be said that the main mineral aggregate gradation and determine the appropriate amount of asphalt used rather than the quality of asphalt. In the premise of appropriate dosage of asphalt, the porosity of dense graded asphalt concrete in the interior of the often less than 4%, to meet the requirements in the field of porosity (such as less than 6%) under the condition that the permeability often small, not easy to produce water damage; semi open gradation and anti sliding surface porosity of asphalt concrete in the indoor scene is about 8%. The porosity is 10%, water easily through the asphalt concrete layer and cause water damage.

The most critical factor is the aggregate gradation rather than asphalt.

In addition, the anti fatigue damage ability of asphalt concrete and the low temperature crack resistance ability of the surface layer, the usage of the asphalt concrete surface layer is related to the quantity of the asphalt concrete surface layer and the quality of the asphalt. But it has contradiction with the high temperature resistance of the asphalt concrete layer. And once the asphalt surface cracks, as long as the timely closure of the maintenance measures to prevent precipitation from the cracks into the asphalt surface layer, that can basically eliminate the damage of water. Significant effect. The uniformity of the fatigue life of asphalt concrete and asphalt concrete on the viscosity of asphalt and asphalt, and also the amount of (OAC) relevant. The uniformity of asphalt concrete is related to aggregate gradation and construction. Because the fatigue life of asphalt concrete with different aggregate gradation has not been tested in China, it is not sure which factor is the most important one. The low temperature cracking resistance of asphalt concrete is usually related to the thin consistency of asphalt, asphalt content and the quality of asphalt. But it has contradiction with the high temperature resistance of the asphalt concrete layer. And once the asphalt surface cracks, as long as the timely closure of the maintenance measures to prevent precipitation from the cracks into the asphalt surface layer, that can basically eliminate the damage of water.

The observation of the transverse crack of the asphalt pavement of the expressway in North China shows that the number of cracks in the asphalt surface layer, the modified asphalt surface layer and the surface layer of the modified asphalt SMA is not different. Long sections of each kilometer, fewer cracks about 30-40, the majority of 40-50. But the cracks in the heavy asphalt concrete surface layer are less than that of the modified asphalt surface layer. Practice has proved that in the use of heavy traffic asphalt mixture and improve the uniformity of the case, the crack is inevitable, as long as the timely use of sealing measures can greatly reduce and avoid water damage into the rain.

The asphalt mixture is mainly composed of two kinds of materials, such as mineral aggregate and asphalt. Dense asphalt concrete, usually including mineral aggregate, asphalt, and air. In terms of their respective volume percentage, the bulk of the mineral material volume ratio, about 83%-85%, asphalt volume ratio of about 10%-13%, air volume rate of about 3%-4%. It is proved that the performance and durability of asphalt concrete are mainly determined by the type and quality of the ore, the composition of aggregate gradation, the test method of asphalt mixture, the technical index and the standard value of the test specimens. Asphalt is a necessary and important part of asphalt concrete, but it is not the most important factor to determine the physical and chemical properties of asphalt concrete.