The main cause of cracks

• Posted by Mavis Chai October 18, 2022 Filed in Arts & Culture #Asphalt Mixing Plant  103 views
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  There are many reasons for asphalt pavement cracking, which can be roughly divided into three categories:

   

  One is due to the action of traffic load and produced structural failure crack under the action of wheel load, when the pavement structure layer at the bottom of the tensile stress is greater than the tensile strength of its material, produced cracking called load type crack.

  

  The second is the temperature crack caused by the temperature change of asphalt surface, including low temperature shrinkage crack and temperature fatigue crack, called non-load crack.

  Three is often appear in the bridge and culvert at both ends of the transverse crack, or in the section of a long longitudinal crack, mainly caused by soil consolidation subsidence or foundation subsidence, known as settlement crack. Although the reasons of asphalt pavement cracking and the form of cracks are various, but the driving load, asphalt surface temperature change is the main reason of cracking. How to produce asphalt? Clink this link.

   

  Transverse cracks

   

  ⑴ the asphalt surface layer of its own temperature shrinkage cracking;

   

  The semi-rigid base, especially the cracking of cement-stabilized macadamia reflects to the asphalt surface;

   

  (3) The excavation of trenches for buried pipelines in some base and freezing crack of roadbed in frozen areas lead to transverse crack of pavement;

   

  ⑷ Surface construction, the construction joint is not handled well, the joint is not close, poor combination.

   

  The fill on both sides of the bridge, culvert or channel produces consolidation or foundation settlement.

   

  Longitudinal cracks

   

  ⑴ Fill material and fill uneven, and fill density can not meet the design requirements. After a period of natural settlement, especially after rainwater immersion, the strength of the subgrade decreases, and the bearing capacity of part of the subgrade along the slope also decreases, and longitudinal cracks will appear.

   

  The construction, before and after the spread at the cold joint is not seriously treated according to the relevant specifications, the combination is not close and off;

   

  (3) the backfill soil in longitudinal grooves has poor compaction quality and causes subsidence;

   

  (4) The soil treatment at the junction of the new and old road surface is not complete, and the uneven settlement causes longitudinal cracking;

   

  The value of the slope is less than the design value, the slope compaction is not enough and the edge groove is too deep to make the actual filling height increase and landslide caused by longitudinal cracking.

   

  The reticular cracks

   

  (1) The subgrade local compactness is insufficient or the base material is not partially loose plate body, so that the pavement bearing capacity to decrease the formation of cracks;

   

  ⑵ The quality of asphalt and asphalt mixture is poor. Asphalt has low elongation and poor crack resistance. Asphalt mixture mixing time is too long, mixing temperature is too high or in the storage bin storage time is too long, so that the asphalt becomes hard, sensitive to tensile strain and resulting cracks;

   

  ⑶ asphalt layer thickness is insufficient, the interlayer bond is poor, water infiltration, the formation of cracks;

   

  (4) Fatigue cracks caused by repeated driving loads.

   

  ⑸ external causes such as pollution, corrosion caused by the local network crack.

   

  Reflective crack

   

  (1) In the cracked old asphalt, old cement concrete pavement layer cover asphalt surface layer, due to the change in temperature (reduce), the old pavement crack continues to expand, to also in the temperature contraction of the new asphalt surface layer an additional stress, so that the new layer in the old crack disconnect.

  The semi-rigid base temperature shrinkage and dry shrinkage cracking caused by reflection cracks.