COVER 0800910 - Caterpillar

Always use clean water when filling water tank for the spray system. Clogged openings in the spray bar will prevent even water distribution and could result in picking up the new asphalt. If freezing conditions exist, drain the water system completely to avoid damage to the system.
Rolling Procedures
With double drum rollers there are four possible vibration on-off combinations. 1. On thin overlays of 25 mm (1 in) or less, vibration may not be used at all. The roller can also be run in the static mode for finish rolling to smooth out any drum marks. 2. On some difficult mixes and mats less the 50 mm (2 in) thickness, it may be best to run with the lead drum vibrating and the trailing drum static. 3. If the laydown thickness is greater than 50 mm (2 in), it is best to roll with both drums vibrating for maximum compactive effort. 4. It is also possible to run with the lead drum static and the trailing drum vibrating. This method is not recommended since the static drum will tend to push the material.Of all the variables in asphalt compaction, the temperature of the mix at the time of compaction is probably the most significant.If the temperature is too high, the mix will disperse easily under the force of the compactor causing waves and creases.If the temperature is too low, the mix will be difficult to compact.Such things as ambient air temperature, base temperature, wind conditions, aggregate size, viscosity of the asphalt and thickness of the mat are factors influencing the proper mix temperature. What is desired is a temperature high enough to allow time to achieve compaction before it cools too much for further rolling to be effective.Cooling time of the asphalt mix must be kept in mind as this will partly determine the speed required of the compactor. For efficient compaction, it is generally agreed that density must be reached before the asphalt mix cools to 79°C (175°F). If possible, set up a test strip before the actual job starts. The test strip will verify the proper amplitude frequency, roller speed and rolling pattern. It will assure the density will be reached while maintaining a proper surface finish. The test strip will also confirm if the proper compactor has been selected or whether additional units will be required to meet production.If the test strip does not meet density requirements, slow down the roller. Take density tests after each pass of the roller until density is achieved. Using this