This article will introduce 8 kinds of asphalt pavement problems and their handling measures.
Asphalt surface layer segregation
Causes
1. Poorly graded asphalt mixture.
2. Uneven mixing of the mixture, loading and unloading, transportation, paving process occurs during the segregation.
3. The ratio between the nominal maximum particle size of the mixture aggregate and the thickness of the paving surface layer does not match.
4. Poor working condition of pavers.
Prevention and handling measures
1. Properly select the small level of aggregate nominal maximum particle size of asphalt mixture, in order to adapt to the thickness of the surface layer.
2. Properly adjust the production ratio of mineral grading, so that the slightly coarse aggregate close to the upper limit of the grading range, the finer aggregate close to the lower limit of the grading range.
3. Transport material should be loaded in at least three times to avoid forming a cone so that the coarse material rolls down to the bottom of the cone.
4. Paver adjustment to the best state, the screed before the material door opening should be adapted to the maximum particle size of the aggregate, the height of the mixture on the spiral fabric should be basically the same, the material surface should be higher than the spiral fabric 2 / 3 above.
5. Add rubber baffle under the fabricator.
6. Lengthen the spiral conveyor.
Asphalt surface layer compaction is not qualified
Causes
1. Poorly graded asphalt mixture.
2. The asphalt mixture rolling temperature is not enough.
3. Small roller mass and insufficient compaction passes.
4. The roller did not go to the edge.
5. Standard density is not allowed.
6. The control rolling temperature is too low.
Prevention and handling measures
1. Ensure good gradation of asphalt mixture.
2. Do a good job of insulation measures to ensure that the asphalt mixture rolling temperature is not lower than the specified requirements.
3. Choose to use the required quality of roller compaction, compaction number of times in line with the provisions.
4. Curb should be installed before the construction of the asphalt surface layer, the roller should be rolled from the outside to the center, and close to the curb rolling.
5. Strictly carry out asphalt Marshall test to ensure the accuracy of the Marshall standard density.
Asphalt surface layer void rate failed
Causes
1. Marshall test void ratio is large or small.
2. Compaction is not controlled within the specified range.
3. The content of fine aggregate in the mixture is low.
4. Poor control of oil to stone ratio.
Prevention and handling measures
1. Take aggregate sieving at the mouth of the hot bin of the asphalt mixing plant to ensure that the grade of asphalt mixture meets the requirements.
2. Ensure that the production of oil to stone ratio within the specified error range.
3. Control the rolling temperature in the specified range.
4. Select the roller that meets the requirements and control the number of passes of rolling.
5. Strictly control the compaction degree.
Insufficient thickness of asphalt surface layer
Causes
1. The loose-lay coefficient was not carefully determined during the test paving.
2. The thickness of the pavement was not adjusted according to the daily test results during construction.
3. The paver or leveling device is not well tuned.
4. The subgrade elevation exceeded the standard.
Prevention and handling measures
1. Carefully determine the loosening factor during test paving. Adjust according to the actual test situation during daily construction.
2. Adjust the working condition of the paver and leveling device.
3. Check the elevation of the lower seal layer carefully before construction of the surface layer. Suitable treatment measures should be taken for the part of subgrade over elevation. Make up the lower seal layer, and then proceed with the surface layer construction.
4. Check the paving thickness according to the total amount of asphalt mixture paved every day and adjust it in time.
Asphalt surface layer transverse cracks
Causes
1. Base layer cracking reflected to the asphalt surface layer.
2. Base layer excavation trench buried pipeline is not carefully backfilled, compacted.
3. Channel settlement joints, lap plate tail and grass-roots combination of uneven settlement.
Prevention and handling measures
1. Treat the grass-roots level. Take anti-cracking measures to reduce transverse cracks in the grass-roots level.
2. Lay fiberglass net on the top surface of the cracked base layer, the end of the bridge head lapboard and the channel settlement joints to reduce the impact on the surface layer and reduce the transverse cracks of the surface layer.
Longitudinal cracking of asphalt surface layer
Causes
1. Uneven settlement of the foundation causes longitudinal cracking of the roadbed pavement.
2. The roadbed filling uses unqualified filler (such as swelling soil). Roadbed water absorption and expansion triggered by road cracking.
Prevention and handling measures
1. Strengthen the foundation. Use qualified filler to fill the roadbed or treat the filler before filling the roadbed.
2. Excavate and remove a certain width of subgrade on each side of the crack. Use reinforced concrete with a thickness of not less than 20cm to fill the grass-roots level. Add glass fiber mesh treatment on top of it, and then pave the asphalt surface layer.
Uneven settlement of road surface
Causes
1. Soft foundation treatment is not complete resulting in uneven settlement of the roadbed, which causes uneven settlement of the road surface.
2. Soft foundation treatment is not to be settled and stabilized to fill the roadbed, resulting in uneven settlement of the roadbed, which causes uneven settlement of the pavement.
3. Insufficient time for pre-pressure of mounding load causes uneven settlement of pavement after completion of paving.
4. The soft lying layer not found when the roadbed is cleared, causing uneven settlement of the roadbed caused by uneven settlement of the pavement.
5. Roadbed or road base, sub-base compaction is not enough to cause uneven settlement of the road surface.
Prevention and handling measures
1. soft base treatment according to the specification construction, to be settled and stable before pavement construction.
2. according to the design requirements and settlement rate control pile pre-pressure time, avoid early unloading.
3. Strictly control the compaction of roadbed, pavement base and sub-base, especially the compaction before filling.
Asphalt surface contamination of asphalt pavement problems
Causes
1. Cross construction, material trucks driving dripping oil spreading material caused by the road surface is polluted.
2. Mortar pollution from the construction of other projects.
3. The central divider backfill soil falls on the road, or the soil is spilled onto the road when greening works are carried out, which causes road pollution.
4. Diesel leakage from various construction machinery.
5. The right-of-way is not hardened, and watering produces mud and water pollution.
Prevention and handling measures
1. Implement road traffic control. Standardize the route of construction vehicles. Prohibit vehicles from dripping oil and spreading materials. 2. side slope, pressure top, fence construction, central divider backfill or greening works should be in the asphalt pavement surface mat color striped cloth isolation.
3. The central divider watering should be sprayed. Should not wash watering, or use open trench digging pit watering.
4. As far as possible, the works that will produce pollution should be completed before the construction of asphalt concrete pavement.
5. Harden or take other measures for entrances and exits.