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Candidates taking the Civil PE exam should be familiar with the types of equipment commonly used in civil engineering construction projects. This familiarity will aid the designer in understanding the capabilities and limitations of such equipment in particular site contexts. In order to provide accurate construction estimates, it is also essential to understand what equipment will be necessary for the project work.
1. Figuring Out Which Tasks Need to be Completed
In exploring the types of equipment used in civil engineering, the discussion can be framed around the major types of tasks that are involved in typical projects. These include earthwork operations, material transport, clearing and grubbing, compaction, asphalt and concrete work, and the installation of utilities and other infrastructural elements. Additionally, there are, of course, the tools and equipment used prior to construction, such as those used for surveying and site measurements or analysis, but we will limit our discussion to the equipment used for construction itself. We will also not discuss equipment used for the general demolition of existing structures or infrastructure, although this too is an area that is often part of civil engineering projects.
2. Earthwork Operations
In terms of earthwork operations, there is equipment used for the operations of cutting (or excavating), filling, moving, and transporting. Some equipment can be used for multiple of these purposes, while others are more limited in capability but more efficient in a particular task. It should be noted that the material being worked in earthwork operations includes not only soil, but also potentially rocks, sand, and other material. Excavators and backhoes are used primarily for the purposes of excavating material, though they can also be utilized for some demo operations, the general loading and unloading of a material, or moving it a short distance. Excavators are the larger of the two types of equipment, and they can rotate 360 degrees, while backhoes typically do not. While excavators and backhoes work by digging or scooping a material, a bulldozer (or more simply, a dozer) is used to push through the uppermost layer of soil and distribute it along as it does so. It lends itself to work where there is a need for alterations on a more continuous or linear basis, while the backhoe might be selected for digging a hole or moving earth from a taller mound. A scraper is another type of equipment which may be used in earth-moving operations. It consists of a cutting element that scrapes the soil, which is then carried into a hopper. The load can then be ejected so that it can be released in areas where fill is required. The scraper is typically pulled or pushed by a tractor or dozer. A grader is a type of equipment that is used to level off the uneven surface of a terrain by means of a blade positioned on the underside of the vehicle.
3. More Excavating Tools
Other types of equipment for excavating operations include power shovels, though these are often used in larger contexts such as mining excavations. Unlike backhoes, they utilize a rope or cable system rather than a hydraulic arm, and the bucket may be forward facing. Larger still is the dragline excavator which utilizes a crane and is also more often used for mining operations or in port construction. A clamshell excavator is a type of equipment that utilizes a two-piece bucket with a middle hinge. This may be attached to a hydraulic arm or a crane with cable system. They are often used for dredging operations.
4. Dump Trucks
Dump trucks are typically used to move or haul materials over a distance. There are various types of dump trucks with the standard (or rear) dump truck being the most common. Other types include side dump trucks and end dump trucks which are sometimes used where more capacity is required. Bottom-type dump trucks have a clamshell bottom so that the material can be released below the carrier.
5. Clearing Property
For clearing and grubbing, the removal of vegetation both above and below ground is necessary for construction - equipment includes hand tools as well as the excavating equipment described above. Other equipment includes mulchers, brush mowers, and grubbers. Mulchers do just as the name implies and turn brush into mulch. Brush mowers are used to clear vegetation above ground, while brush grubbers are used to remove small stumps and roots from below the ground.
6. Compaction Equipment
Compaction equipment for earthwork includes various types of rollers as well as tamping/ramming type compactors. Smooth drum rollers are a common type. These may have a single or double drum. There are also static type and vibration type rollers. The vibration of a drum assists with the compaction and is commonly used with certain types of material such as non-uniformly graded soils. Sheep foot (or pad) type rollers have drums with projecting elements and are commonly used where compaction of clay is necessary. Pneumatic type compactors utilize a vehicle's tires rather than a drum. This is commonly used as final compaction method on asphalt pavements. With tamping (or ramming) type compactors, impact forces are applied to a surface to compact a material. Vibratory plate type compactors are also used and utilize vibration rather than a ramming action for compaction. These non-roller types of compactors are pushed by an individual rather than a vehicle and are often used for smaller areas than might be covered with rollers but are appropriate for certain situations such as preparing an area for a footing or small slab.
7. Preparing Trenches
For the preparation of trenches, the installation of utility lines, or agricultural purposes, trenching equipment is typically used. This type of equipment includes trenchers which can be of the wheel or ladder type. The wheel type utilizes a large wheel at the front of the vehicle with various types of cutting edges and scooping buckets. The ladder type is similar but uses a more elongated apparatus with buckets moving along a chain roller.
8. Asphalt and Concrete Equipment
Lastly in our discussion, we will touch upon the types of equipment used in work related to asphalt and concrete. A miller is a type of equipment that is used to mill the exposed surface of an existing layer of asphalt. This allows for a rough grooved and slip-resistant surface upon which a new layer of asphalt can then be added. Sweeping vehicles, or sweepers, are often used after the milling equipment is used in order to clear the surface of rocks and other debris. The actual paving operations for new asphalt material are accomplished with asphalt pavers. The hot mix asphalt deposited from the equipment is leveled out by means of a screed component. This screed also allows the thickness and profile of the asphalt layer to be controlled. Finally, compacting equipment, such as the pneumatic type compactor mentioned above, is typically utilized to ensure the proper compaction of the asphalt.
9. Installing Concrete
Common equipment for concrete work includes mixers, vibrators, pavers, conveyors, boom placers, and pumps. Mixers blend the components of concrete mix together, and there are two broad categories of mixer types, batch and continuous. Batch mixers include varieties of the drum type and the pan type. With the drum type, the components are mixed through the rotation of a drum. In contrast, the pan type utilizes a rotating set of blades within a container to accomplish the mixing. Mixing trucks allow for the mixing to occur during transport from a plant. Concrete vibrators are used to reduce the presence of air bubbles within a volume of placed concrete. Concrete pavers are used commonly in the construction of concrete roadways, with the most typical type for this application being the slipform type. With the slipform type paver, once the machine places the concrete, it is then spread evenly with augurs before being smoothed off by means of a strike off plate. It should be noted that there are also more specialized concrete pavers for the creation of concrete curbs and gutters. A concrete conveyor is a means of moving concrete material from a mixer to another location where it can then be poured into place. Concrete can also be moved and placed by means of a boom placer. These utilize concrete pumps to convey the liquid concrete to the end of the placing boom.
Conclusion
The equipment described above is by no means an exhaustive list of equipment used in the construction of civil engineering projects. These are just some of the more commonly used types of equipment with which the civil engineer should be familiar. Understanding how such equipment is utilized by contractors can provide for a better understanding of the construction process and consequently result in more successful civil engineering projects.
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