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high-amplitude vibratory compaction . The expectation is that the more even and high-quality the asphalt compaction is , the more durable and long-lasting the pavement will be . More asphalt paving projects , especially road projects , are being tendered with demands for detailed , comprehensive compaction measurement . “ There are ways to measure , monitor , document and control compaction and compaction processes ,” stated Matt Graves , director of marketing , for Wirtgen America , Antioch , Tenn ., which offers HAMM compaction equipment . “ There are technologies that use a GNSS receiver to continuously determine the position of the rollers and combines this data with the measured values that have been collected . A panel PC with a touchscreen in the operator ’ s platform then displays all the data in a single package in the form of a real-time ‘ compaction map ’ – this includes additional parameters such as current speed , amplitude and frequency , as well as process data such as the number of passes , asphalt temperature and stiffness value .” In comparison to other methods , compactors with oscillation drum rollers have a place and serve a distinct role . “ Standard vibration has the best / most effective compaction force ,” stated Erdmann . “ The higher the vibration amplitude and the static linear load of a roller the higher the compactive force . “ For breakdown compaction and hard to compact materials , standard vibration is more suitable then oscillation . Oscillation is considered to be ‘ gentle compaction ,’ since it does not impact the material . It makes it ideal for joint compaction , because the drum won ’ t ‘ bounce ’ off the cold mat while compacting the hot mat . In a sense , the oscillating motion manipulates the material and sort of pushes the asphalt into place and reduces air voids .” Erdmann continued : “ The same is true for finish rolling ; since the oscillating drum won ’ t ‘ bounce ’ on the cooling hot asphalt mat , it can ’ t break the aggregate and yet achieve additional density as long as the material is still pliable enough .
Static steel drum rollers are becoming more and more a thing of the past . Usually , static rollers were used in applications where standard vibration could no longer be used . Oscillation and horizontally directed vibration have additional benefits over static rolling , since the material manipulation has a positive side effect of sealing the asphalt finish . This is probably the reason for the trend why oscillating rollers are more and more replacing static steel drum rollers .”
Think about it , oscillation is a non-vertical force that applies compaction energy without impact . In other words , there is no up-and-down vibration movement . The drum stays in contact with the surface , and there are no repeated impacts to the surface for compaction . The technology creates horizontal motion only . This provides more compaction force than static rolling , but less force than traditional vibration . The needs of the compaction project will dictate the best solution . “ It really comes down to the application and / or the needs of the job ,” Dulak stated . “ Vibratory rollers have a high vertical compaction force that penetrates deeper in the substrate . Oscillating rollers are designed to reduce amplitude — this provides the compaction and finish desired , while minimizing potentially damaging vibratory forces to the mat or any nearby structures .” Mat temperature will also be a factor . “ As rule of thumb compaction mat temperatures will vary depending on the material but are usually between 200- and 280-degreesF , from start to finish ,” Palanisamy said . “ With oscillation rollers , matt temperatures can be as low as 150-degreesF .”
In addition to advantages in close proximity to structures , addressing longitudinal pavement joints , and on bridge decks , oscillation compaction is said to be good for achieving target densities with special mix designs where vibratory compaction doesn ’ t yield the desired results and when
Static steel drum rollers are becoming more and more a thing of the past . Usually , static rollers were used in applications where standard vibration could no longer be used .
pushing production into the colder seasons where compaction is needed . Areas the paving contractor needs to be aware of with oscillation drum rollers is the wear life of the oscillation drum and regular maintenance . “ Oscillation rollers feature a thinner drum for the oscillation to create the back and forth movement--which raises the question of how long the drum will last ,” stated Palanisamy . “ Contractors are advised to work with manufacturers who have the best drum material that prolongs the wear life and also the best extended warranty protection , in case of early wear or unanticipated failure . “ Additionally , contractors should consider how easy routine maintenance can be performed . For instance , can the belts that drive the eccentric weights be changed out in the field or does the machine need to be brought into the shop for service ? Maintenance needs can have a direct impact on uptime .”
In summary , oscillatory compaction systems can be used on all phases of the compaction process . It delivers the best results on thin asphalt layers – less than 2-inches , compaction of materials with sensitive substructure or next to buildings , or on bridge decks or overpasses . In addition to excelling in urban city vibration sensitive areas , asphalt roller oscillation succeeds with joint compaction , such as longitudinal joints , where it prevents damage to existing pavements while pressing the joint between lanes tightly , and transverse joints , where its massaging action creates a tighter joint .
Oscillation compaction truly holds a respected place in the asphalt paving contractor ’ s arsenal of productive tools .
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