Characteristics and causes of asphalt road disease
Asphalt pavement is the most common pavement structure in China. It has the advantages of smooth surface, firmness, no seams, comfortable running, wearable, low noise, short construction period, simple maintenance, water absorption, and suitable for construction by stages. Get a wide range of applications. However, due to the difference of asphalt concrete material and the influence of design and construction level, asphalt pavement often has eight common diseases such as cracks, rutting, loosening, frost heaving, subsidence, overcooling, . The emergence of these diseases seriously affected the driving speed, traffic safety, increased vehicle wear and tear, shortening the life of asphalt pavement.
1.cracks. Asphalt pavement in the early stages, will inevitably produce various forms of cracks. Early cracks will not affect the use of asphalt pavement performance, but with the invasion of rain and the role of external forces, will gradually produce structural damage to asphalt pavement. Cracks from the manifestations are divided into horizontal cracks, longitudinal cracks and mesh cracks three. The causes are as follows: 1, transverse cracks, often due to the role of temperature stress, pavement fatigue cracks. This kind of temperature crack often starts from the surface with the highest rate of temperature change and extends down quickly, and the aging of the asphalt occurs with time. The crack resistance of the asphalt surface decreases year by year and the temperature crack increases.longitudinal cracks, mainly due to uneven foundation and fill, especially in the widening of the old roadbed, because the soil step treatment is not standardized, layered filling thickness and compaction degree of lax control. 3, the network cracks, mostly due to the early surface cracks through the surface water infiltration, erosion, pump slurry, resulting in a seam as the center of the subsidence deformation, while generating new cracks and even broken damage.
2. the rut. Mainly pavement structure and soil in the road under the action of repeated replenishment compaction, so that the lateral displacement of the structural layer material, resulting in cumulative permanent deformation. 3, the rain intrusion into the interior of asphalt concrete; 4, the base layer with unstable mezzanine, resulting in the formation of lateral pavement rutting waveforms. 2, the surface of excessive wear and tear;
3.loose. Loose asphalt pavement is a common disease, a direct impact on traffic safety. General performance, the surface layer of aggregate particles fall off, the thickness of aggregate loss from the sand, road wear, road surface Ma Ma, surface peeling, if not treated in time, from the road surface down the formation of pits. Looseness may occur throughout the pavement surface. May also appear in the local area, usually in the wheel with a more serious. The formation of the main reasons are the following seven aspects: 1, bitumen asphalt mixture is too small, low asphalt ratio, asphalt and aggregate between the poor adhesion; 2, low temperature construction, compactness, asphalt surface internal voids 4, the temperature is too high when mixing, leading to asphalt aging; 5, the grass-roots soft and the base is too soft; 3, the aggregate mud content exceeds the standard, the aggregate particles are dust wrapped, so that the bitumen membrane can not be bonded to the aggregate particles; 6, mistakenly selected the acidic aggregate, and poor adhesion of asphalt; 7, water gradually penetrate the interface of asphalt and aggregate, reducing the adhesion and adhesion of asphalt.
4. frost heave boil. Mainly in the freezing and thawing period, because of water intrusion and subgrade soil water stability is poor, the roadbed after the accumulation of moisture caused by road surface swelling and cracking. If not handled in time, to the frost heave pavement completely melted, the weight of the vehicle will have a road boil, the traffic safety is a great risk.
5. subsidence. Subsidence is one of the most common types of pavement deformation. It is characterized by large area and deep level of structure. It mainly occurs in the excavation section and the boundary between excavation and excavation. 2, the road surface strength can not meet the increasing traffic volume, prone to fatigue and damage; the road surface can not meet the needs of the road surface, 4, the uneven settlement of the bridge pavement caused by subsidence and the bridge with the dislocation. 3, subgrade or grass-roots strength is insufficient or fill the roadbed strength is inconsistent, in the vehicle load, the roadbed or base structure damage caused by subsidence;
6.a package. Refers to the local uplift of the asphalt pavement. 2, the base layer or the bottom layer without compaction, strength, deformation, displacement; 3, the quality of the road surface layer of the road surface is not good, asphalt mixture paving uneven, lo