Slope compaction
Slope compaction is often required for the construction of dams and canals. Dams with an impervious upstream facing of asphalt or concrete are some examples where goods slope compaction is required. A self-propelled single drum vibratory roller is the most suitable type of machine for slope compaction. Whether the roller needs to be winch-aided or not depends on the incline. When compacting, the vibration should be switched on for the upward journey and off for the downward one. If the roller is winched a protection grip must be used to protect the operator. A safety wire should also be attached to the machine if the winch wire breaks. Always use a roller with a rollover protection system (ROPS) and make sure the operator uses a seat belt and hardhat. Prior to using a machine on a steep slope, check with the manufacturer that it is can operate continuously on the incline in question.
Ground vibration
The actual transmission of ground vibrations during vibratory compaction depends largely on the size of the roller, the amplitude and the material that is being compacted. If there is a risk of damage to surrounding buildings, these should be surveyed for existing cracks and other damage prior to starting the compaction work. It is always very difficult to prove the cause of certain damage after the compaction has been carried out. Vibrations can be sensed by humans and noticed in buildings long before they reach a level where damage will occur. This is why many house owners will try and blame vibratory compaction for damage that has been present before. The following guidelines can be used to calculate a safety distance for vibratory rollers:
| Towed and self-propelled vibratory rollers with pneumatic drive wheels (using high amplitude on soil) Safety distance in meters= 1,5x drum module weight |
| Vibratory tandem rollers (small to medium amplitude used on asphalt) Safety distance in meters= 1,0 x drum module weight. |
Disclaimer: The above guidelines are offered as an indication of safe distances. Dynapac does not guarantee the safety of surrounding buildings and cannot be held responsible in any way if damage occurs when working according to the guidelines.
Confined areas/trench compaction
Safety is a main concern when working in confined areas and trenches. The risk of inhaling exhaust fumes and the risk of being hit by a machine is bigger if you are working in a tight area. Using remote controlled machines will free the operator from many of the dangers associated with this kind of work including that of collapsing trench walls etc.
Compaction over pipes and culverts (protective layers) It is necessary to have a certain layer thickness over pipes, culverts and other structures in the ground to avoid damaging them during compaction. The following values are recommended layer thickness. DISCLAIMER!!!
| Compactor | Weight class | Protective layer |
| Rammer | 70 kg | 0,25 m |
| Vibratory plate compactor | 50 kg | 0,10 m |
| | 100 kg | 0,10 m |
| | 200 kg | 0,15 m |
| | 400 kg | 0,25 m |
| | 600 kg | 0,40 m |
| | | |
| Single drum roller | 15 kN/m | 0,50 m |
| (Static linear load) | 30 kN/m | 1,0 m |
| | 45 kN/m | 1,5 m |
| | 60 kN/m | 2,0 m |
| | | |
| Vibratory tandem roller | 5 kN/m | 0,15 m |
| | 10 kN/m | 0,35 m |
| | 15 kN/m | 0,50 m |
| | 20 kN/m | 0,70 m |
| | | |
| Static three-wheel roller | 50 kN/m | 0,80 m |
| | | |
| Pneumatic tyred roller | 15 kN | 0,50 m |
| Load per tyre | 30 kN | 0,80 m |
| | | |
Dry compaction
Most soils are normally most effectively compacted at the optimum water content. However, in some areas such as arid or semi-arid areas it may be impractical or too costly to water the soil. In such cases, gravel and sand, can be compacted in a dry state (water content <1-2 %). It is important to take the saline content of the soil into account. High salt content may affect the final properties of the soil. Dry compaction has been applied on relatively thick layers in road and airfield applications in desert areas.
Deep compaction
Thick layers of water saturated sand or gravel with a fine content less than 5-10 % can be compacted in relatively thick layers with vibratory rollers. This can be used for compaction of dredged sand in land reclamation projects from the water level and up. The table below indicates the compaction depth for some different machine types.
| Roller size | Depth for medium-dense relative density, m | Maximum depth for density increase, m |
| CA 302 | 1,5-2,0 | about 2,5 |
| CA 512 | 2,0-2,5 | about 3,5 |
| CA 602 | 3,0-4,0 | about 5 |
Continuous compaction control (CCC)
The only way to get full coverage of the compaction results on a certain job is to use the roller as a measuring device. A vibratory roller can be used to measure the stiffness of the compacted material and the stiffness is a very good indicator of the compaction of a granular material. The roller measures and records the stiffness values at the same time as it is compacting the material. This will give the operator information of the level of compaction of different areas of the job site well as an indication of the level of homogeneity of the compaction. Using CCC early in the compaction process can locate weak areas that can be corrected before the project has progressed too far. This can lead to substatial savings compared to having to correct failures later in the project. Dynapac can provide a Compaction Meter on all single drum rollers and the possibility of adding a computer for continuous documentation of the compaction results. It is also possible to use satellite positioning to accurately locate the roller on the jobsite.
The influence of water content
Lack of or excess water is equally bad for the compaction performance in almost any soil material. Every material has a water content where the compaction is most efficient (Optimum water content) If the actual water content deviates from the optimum it means that extra passes are required to reach the compaction requirements or that the layer thickness must be decreased.