In every home project, be it a DIY one or one that is done by a contractor, the people involved will be needing different sets of equipment to get the job done correctly. The same is true with paving an asphalt driveway. Different machinery is needed to prepare the base of the driveway, and different machinery will be needed when it is time to lay the sub-base materials, the asphalt, and compacting them. One of the many equipment that is needed to get this done is a roller.
There are 6 different types of rollers that are commonly used when paving a driveway. These rollers are mainly used for compaction: Cylindrical Roller, Sheepsfoot Roller, Pneumatic Roller, Smooth-Wheeled Roller, Vibratory Roller, and Grid Roller. Each type of roller is used for a specific purpose. And these purposes are laid down below.
This is a light weight roller used for light compaction. This is made of iron, concrete, or stone. A cylindrical roller can be handled by hands or bullocks. Generally, this type of roller comes in around 1 meter in diameter and 1 ½ meter in length, but you may see this kind of roller in dimensions bigger than the ones mentioned here. When using this type of roller, you can expect compact pressure on the area about 7kg/cm³.
This type of roller is commonly known as a tamping roller for the reason that its drum has rectangular or circular protrusions leaving its path look like it is stamped. It is also because of the protrusion that this type of roller is called a sheepsfoot roller. You will commonly see this type of roller being used to compact cohesive soils like clays. This type of roller will not work on sandy bases. If the weight of compaction for cylindrical roller is a fixed 7kg/cm³, in a sheepsfoot roller, you can increase the weight by adding water in the drum or adding damp sand. However, the weight of the compactor must be determined by these factors:
- Weight of the roller
- Area of each protrusion (feet)
- Number of feet in contact when rolling the drum
- Total number of feet per drum
- Maximum pressure exerted on the soil when rolling the drum
The total weight added to each drum should not exceed 7kg/cm2 (light rollers) and 70kg/cm2 (giant rollers). Before using this type of roller, it is recommended the surface has been run over by a smooth-wheeled roller.
Also known as Rubber Tired Roller, this compactor is a loaded wagon with several tires (up to six) closely spaced next to each other. This roller can provide uniform pressure to the base along its width. And just like the first type of roller, a pneumatic (tire) roller can also produce 7 kg/cm3 of pressure. You can typically see this type of roller used to compact cold asphalt pavements, loose soil, or a soft base. But, this can also be used to compact bases with closely graded sands and cohesive soils with very fine grains. Although, you will not see the same results as when you compact these types of base materials with a smooth-wheeled roller.
Just like its predecessor, this type of roller can be seen with a large steel drum placed in front and up to two wheels of drums at the back. You will see two varieties of this roller being used by contractors. These are Tandem Rollers and Three-wheeled Rollers. Tandem rollers come with one wheel drum in front and at the back. This roller comes up to 8 tons of weight. While a three-wheeled roller, as the name suggests, has one wheel drum in front and two wheel drums at the back that has a weight of up to 10 tons. It is possible to increase the weight of the drums as you see fit. This can also be done with water, wet sand or other materials that can be used to increase the weight of the drums.
This type of roller is also commonly used in asphalt paving projects. This is used to compact granular bases in asphalt pavements. This can also be used to compact bases for asphaltic concrete projects. This comes in a diameter between 0.9 to 1.5 meter with a width between 1.2 meter to 1.9 meter. Vibratory rollers are self-propelled. They come weighing up to 6 tons. This type of roller is so called vibratory because it produces vibrations which are caused by an eccentric shaft inside the roller.
If vibratory rollers are self-propelled, grid rollers are generally towed. The roller is made of a cylindrical steel bars. The weight of this type of roller varies from 5 tons up to 15 tons (ballasted). If you are planning to compact coarse grained bases, then you should use this type of roller.