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Repairing Defective Flexible Pavements
Sprayed Asphalt Surface Treatment

Equipment Operator Basic - Beginning construction equipment operators manual
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After the base course has passed the compaction test, prime the hole with a light application of asphalt, which can either be sprayed or brushed on. The prime material must be thin enough so that it can be applied lightly. NOTE: An excess of asphalt prime coat will flush into the patch mix and causes bleeding. The final step in the preparation of the hole is to apply a tack coat to the vertical faces, as shown in figure 16-26. Bituminous  Materials  Replacement The first step in the replacement of the paving materials is to obtain a sufficient quantity of material to complete the project. Use a hot mix if possible because it is stronger and lasts much longer. To  allow  for compaction  when  using  a  hot  mix,  you  should  overfill the area approximately 40 percent of the pavement thickness. When a cold mix is used, it should be spread and rolled in layers with each layer not to exceed 1 1/2 times the maximum aggregate size in the mix. When cold mix is spread, keep the material as level as possible to prevent segregation. Both hot and cold mixes can be spread by grader, by paver, or by hand, depending on the size of the repair. Compaction  of  bituminous  materials  is  done  with steel-wheel rollers and pneumatic-tired rollers on larger areas, or with vibrator tampers, vibratory patch rollers, and hand tampers on smaller areas. Compaction is an important  part  of  the  patching  operation.  The  rolling operation on hot mix should begin immediately after the material  is  placed.  Cold  mix  should  be  rolled  after Figure 16-26.-Tack coat application to the vertical faces. 16-22 proper aeration of the material. The edges of the patch should be rolled first. This seals the edges and prevents the  material  from  dishing  out  and  water  from infiltrating. When cold mix is used, the patch may have a  porous  surface  and  require  waterproofing.  This  can be done by applying a sand seal or by applying a thin layer of portland cement and tamping it in. Obtaining  a  smooth  riding  surface  requires  care. Too many patches are built as mounds that result as bumps in the road A straightedge should be used as a guide to finish the patch. The patch should not be lower than the rest of the pavement. Instead, it should be level with or one-eighth inch higher than the surrounding area.  Figure  16-27  shows  the  steps  in  patching  a pothole. Figure 16-27.-Steps in patching a pothole.







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