9. Compact the surface.10. Apply a seal coat when necessary.When you are mixing in place (road mix), here aresome helpful hints:1. Do not try to buck nature; stop operations whenyou are working under adverse weather conditions.2. Keep the mixture or aggregate in a well-packedwindrow for better water shedding and control.3. Provide drainage cuts through the windrowduring heavy rains.4. When a grader comes to the end of a section witha full blade, lift the blade rapidly to avoid carryingmaterials into the next section.5. The distributor spray must be cut sharply atsectional joints; carry-over to the next section will causeundesirable fat joints.6. Plan the work to avoid inconvenience to traffic.7. Apply the asphalt at the recommended sprayingviscosity to ensure uniform application.8. Using a shoe on the outer end of the grader bladeor moldboard helps obtain a good edge during spreadingoperations.9. Aggregate in shaded areas usually requires extraaeration.ROAD-MIXING METHODSTwo methods of road mixing are travel plant mixingand blade mixing.Travel Plant MixingWhen a travel plant is used for mixing (fig. 16-7),the loose aggregate is dumped, mixed, and bladed intouniform windrows, and evened when necessary. Thewindrow should be sufficient to cover the section of thearea to be paved with enough loose material to give thedesired compacted depth and width. As the bucketloader tows the mixer and elevates the aggregate to themixer hopper, the mixer meters the aggregate, sprays itwith the correct amount of bitumen, mixes these twouniformly, and redeposits the mix into another windrowbehind the plant. The rate of travel and the mixingoperation should be controlled so that all particles of theaggregate are coated and the mix is uniform. Accuracyin proportioning the mix is extremely important.The travel plant method usually produces a moreuniform mix of higher quality than blade mixing.Figure 16-7.–Schematic layout of a travel plant.16-14
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