Construction Equipment Used in Road Construction

MAJOR CONSTRUCTION EQUIPMENT USED IN

ROAD CONSTRUCTION PROJECTS

Satya Narayan Shah B.Sc. Engg (Mech), M.Sc. (M.Engg &Management) August, 2006

Satya Narayan Shah B.Sc. Engg (Mech), M.Sc. (M.Engg &Management)

MAJOR CONSTRUCTION EQUIPMENT USED IN ROAD CONSTRUCTION PROJECTS

PNEUMATIC TOOLS

ROCK CRUSHERS, ASPHALT AND CONCRETE EQUIPMENT

EARTH MOVING AND COMPACTION

ANCILLARY EQUIPMENT

1. Air Compressor 2. Rock Drill/ Jack Hammer/ Steel Drill/ Wood Drill 3. Concrete Breaker 4. Asphalt Cutter 5. Rock Splitter 6. Compactor 7. Impact Wrenches/ Nail Driver 8. Grinder 9. Concrete Vibrator 10. Backfill Tamper 11. Circular Saw/ Chain Saw 12. Road Broom

A. Rock Crushers 1. Jaw Crushers, Double Roll Crusher, Cone Crusher, Hammer Mill 2. Screens 3. Conveyors B. Asphalt Plant 1. Central Mix Plant (Batch Plant/ Continuous Mix Plant) 2. Hot Oil Heater 3. Asphalt Melter 4. Bitumen Distributor (Trailer Mounted/ Self propelled) 5. Asphalt kettle/ Bitumen Heater 6. Portable Mix Plant 7. Pavers 8. Rotary Sweeper 9. Aggregate Spreader C. Concrete Plant 1.CONSTRUCTION Aggregate Batching Plant EQUIPMENT 2. Concrete Mixers 3. Concrete Pavers 4. Concrete Vibrator 5. Concrete Saw 6. Portable Concrete Curing Machine

A. Earth Moving 1. Dozers (Track/ Wheel) 2. Loader / Shovel (Track / Wheel) 3. Excavator/ Backhoe (Track/ wheel) 4. Scrapers 5. Grader 6. Hauler (Off-highway haulers, Tipper Truck, Mini Dumper) B. Compaction Equipment 1. Sheep foot Roller, Tamping Roller 2. Steel Wheel Vibratory Roller 3. Steel Wheel Static Roller 4. Pneumatic Roller 5. Plate compactor/ Rammer

1. Water Distributor 2. Rotary Tiller Mixer 3. Portable Electric generator 4. Welding generator 5. Crane 6. Pile Driver 7. Water Pump 8. Boring Rig 9. Fork Lift 10. Trucks Flat Bed 11. Low Bed Transporter

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CONSTRUCTION EQUIPMENT

Air Compressors & Pneumatic Tools: Air Compressor: An air compressor is a machine for compressing air from initial intake pressure to a higher exhaust pressure through reduction in volume. It provides air energy to drive pneumatic tools and other pneumatic equipment to perform specific jobs. It consists of a driving power unit, a compressor and an air reservoirs and accessories. The driving power unit is generally a diesel engine but sometimes gasoline engine or electrical motors are also used to drive the compressor. The air compressor may be reciprocating, rotary or screw type. Major point of consideration to select an air compressor is the volume of air production per minute at a specific pressure. Commonly, Air compressors available for the road maintenance and construction purposes are ranging from 125 cfm to 6oo cfm at 80 to 125 psi. The number of pneumatic tools to be used gives the proper size of the air compressor. The requirement of air for the most common pneumatic tools is given as below. Pneumatic Tools: Advantages of pneumatic tools a. They are easier to maintain b. Ease of operation c. Durability d. Working ability in various climatic conditions e. Safer in use f. Not damaged if they are overloaded Selection of Pneumatic Tools Pressure Functions Pneumatic Tools Air in psi Quantity in cfm Paving Breaker 60-80 80-90 Demolish concrete, brick, asphalt, macadam, ice, column, piers, and foundations etc. Nail Driver 30-40 90 Drive nails riveting, drive spikes and cutting off the head of rivets. Circular saw 70-80 80-100 Cut wood, brick, stone, concrete, tile, asbestos cement sheets, steel, cast iron, etc Chain Saw 90 80-100 Cut hard wood logs, tree branches Sump Pump 100 80-90 De-watering Backfill Tamper 24-27 80-90 Compact earth in confined areas that are not accessible to other types of compactors Concrete vibrator 20-50 85-90 Compact concrete while casting Portable Grinder 45 90 Grind metal, brushing materials etc. Steel Drill 27 90-100 Drill holes 80-100 Drill holes into rocks for blasting, rock Rock drill (Jack Hammer) 15-25 bolting or other purposes 2


Pneumatic Tools

0’- 2’ hole 2’-8’ hole 8’-12’ hole 12’-16’ hole 16’- 14’ hole 8’-24’ hole Drifter Drill Mounted)

Air Quantity in cfm 30-50 55-75 80-100 90-110 150-175

(wagon 150-275

Pressure in psi

105

Functions

Drill holes into rocks on almost any slope,

Different pneumatic tools have been shown in the attached sheets. The functions of these tools can be understood from the above table.

ASPHALT AND CONCRETE EQUIPMENT ASPHALT EQUIPMENT 1. Central Mix Plants: A central mix plant is an assembly of specialized equipment, which produces paving mixtures of aggregate and bituminous material. It is erected and remains, at its selected site till the job is done. They are commonly available in 100 to 150 ton-per-hour (TPH) plants and 80 to 120 TPH plants. There are following classes of Asphalt plants as per the required products. 1. High type: Produces mix for suitable for construction heavy duty wearing surfaces. It employees two separate devices for accurate separation and mixing of sands and gravels and one for precise injection of fines 2. Intermediate type: Produces mix normally for laydown of wearing surfaces for average traffic conditions. It blends sands and gravels in one device only. 3. Soil stabilization:

Produce material for uses ranging from base course to light duty wearing surfaces. Asphalt central mix plants are further classified as Batch Plants and Continuous Plant according to the flow of final product. 2. Portable Mix Plant: All the above equipment are generally used in a road construction, while for maintenance purposes 3- to – 10 TPH Drier-Mixer (Portable Mix Plant) is used due to its portability and low operating costs. A bitumen heater or kettle is used to heat the bitumen at required temperature to feed the Portable Mix Plant. 3. Aggregate Spreader: This is an attachment to the tipping trucks, which can be adjusted to deliver controlled quantity of aggregate over the surface. 4. Rotary Sweeper: This is used to remove dust from the surface before paving to obtain proper bonding between newly laid asphalt and the old pavement. 5. Asphalt distributor: The asphalt distributor is a truck-mounted or trailer mounted unit consisting of an insulated tank, heating system, an asphalt pump, and a circulating and spraying system. 3


6. Asphalt Pavers: The Paver receives hot bituminous mix and places it to the desired thickness and cross section. The standard paving width is 10 feet. This can be reduced by cutoff shoes to a minimum width of 8 feet, or extended to a maximum width of 12 feet. It is capable of paving 0.25” to 6 inches at the travel speed of 12 feet to 64 feet per minute.

Concrete Equipment 1. Aggregate Batching Plant The aggregate Batching plant is designed to proportion, rapidly and accurately, the sand, gravel, cement and water used in a concrete mix. This equipment is used to have mass production of mix hence it is used in massive concrete casting like bridge construction or concrete road paving. 2. Concrete Mixers This is a portable unit used for small casting works. This machine comes with various capacities ranging from 5 cft to 25 cft.

Earth Moving equipment 1. Bull Dozers: This is the most versatile earthmoving tool as it accomplishes various tasks like pushing, towing, ripping etc. Basically dozer blades consist of a moldboard, cutting edges, end bits and blade arms connecting the blade to the tractor. Blades vary in size and type Straight blade, Angle blade, and Special purpose blade are the main types. Dozers are also equipped with rippers at the rear of the tractor. They are used to loosening the hard soil. Application of Bulldozers: 1. Land clearing: - Bushes and small trees are removed by lowering the blade a few inches into the ground to strike and cut the roots. This is usually down at the lower speed ranges 2. Stripping: - It consists of removal of topsoil that is not usable as fill martial or as a stable sub-grade. 3. Sidehill cutting: - Always start all sidehill cuts from the top to work down with the cut. Working downhill gives advantage of gravity. 4. Backfilling: - Dozers are used to backfill by pushing material directly ahead of the machine over embankments into ditches or directly against the structure. This job may be performed either by making the blade straight or angle. 5. Dozing Rocks and Frozen ground: - Rocks are generally removed by using one corner of the blade so that full power is applied to shorter section of the blade. Frozen ground is broken by tilting the blade to get better penetration. 6. Ditching: - Though this machine is not ideal for this purpose but ditching may be done by straight blade by working at right angle to the length of the ditch. 7. Spreading: - This is done by straight blade dozer so that the material is drifted under the cutting edge directly. Dozing Tips 1. Do not back up further than necessary, and do not push material greater distance than required. 2. Know where the next pass is going to be and where material will be placed. Always plan the work thoroughly. 4


3. Loader/ Shovel This equipment is mainly used for material handling. The following works can be done with this machine - Lowering materials to hopper - To lift and haul around short distance. - Light and medium excavation and dozing - Land clearing 4. Excavator/ Backhoe Excavators are other highly versatile machines in the sense; they can be equipped with several different types of front-end operating attachments, which are easily interchangeable. Excavators are generally available on three types of mountings. Crawler, Truck, and self propelled Tyre Mountings. The common attachments available are Shovel, Hoe, Dragline, and Clamshell- type Bucket. 5. Scrapers Scrapers are primarily designed for self-loading, hauling and dumping during the earthmoving phase of construction. This machine is used during the construction of roads where massive earth excavation is to be done. Generally borrow pit material are excavated with this machine. This machine is capable of excavation, loading, hauling, dumping and compacting. Hence, it may be called a multi purpose machine. 6. Grader Graders are multi purpose machines used for grading, shaping, bank sloping, and ditching and for general construction and maintenance of roads. Grader can be employed for leveling and crowning, mixing and spreading, ditching and bank-sloping and side-casting material. It may also be used for light striping operations but it is not intended for heavy excavation. Grade is also equipped with scarifier, which is used to break the hard material. Tips: ¾ Avoid wet and muddy condition because the traction decreases to maximum extent. ¾ Eliminate turns if it works less than1000feet. To do more passes in such situations reversing the grader is more efficient. ¾ Avoid unnecessary passes if it is possible ¾ Proper tire inflation is very important to gain more efficiency ¾ Proper working speed.- operation should be performed as fast as possible 7. Hauling Equipment: Mainly there are two types of hauling equipment used in the DOR. Tipping Trucks and Mini Dumpers. Compaction Equipment The amount of compaction, which can be obtained, is influenced by the following factors. 1. The moisture content of the soil 2. The nature of the soil (Grain size distribution and physical properties) 3. The type and amount of tractive effort 4. Thickness of lift 5. Climatic conditions 6. Type of equipment Among above factors the last factor is related to the equipment. Compacting effort refers to the method employed by equipment to impart energy into the soil to achieve required compactions. The equipment are designed to use one or a 5


combination the following types of compactive efforts to the soil to achieve ultimate result of compaction. a. Static Weight (or Pressure) b. Crushing c. Kneading Action d. Impact (or Sharp Blow) e. Vibration (or Shaking) Types of Compactors Compactors can be grouped in the following types: 1. Sheep foot 2. Grid or Mesh 3. Vibratory 4. Smooth steel drum 5. Multi tyred pneumatic 6. Heavy pneumatic 7. Vibratory tamping 8. High speed tamping foot 9. Towed tamping foot

SELECTION OF COMPACTOR Compactive Effort

Compactor Zones of Application 100% Clay

100% Sand

Silt

Rock

Sheepsfoot

Static Wt, Kneading Grid

Static Wt, Kneading

Vibratory Static Weight, Vibration Smooth Steel Drum Multi Tyred Pneumatic

Static Weight, Crushing Static Wt, Kneading

Heavy Pneumatic Static Wt, Kneading Vibratory Tamping Foot Static Wt, Impact, Vibration Towed Tamping Foot

Static Wt, Kneading

High Speed Tamping Foot

Cat Tamping Foot

Static Wt, Kneading, Impact, Vibration Cat Rock Tamping Foot

Static Wt, Kneading, Impact, Vibration 6


1. Sheepfoot Roller: A sheepfoot roller is intended to shear and knead the soil to gain the required compacted mass. Since the contact area is relatively small, many passes are necessary to obtain maximum bearing pressure over given area. This type of roller is most effective on cohesive soil and it is not recommended for granular or non-cohesive soils. This type of roller is generally used for 10 to 12 inches of lift thickness. Tip: The roller becomes lighter as the density of the soil increases. 2. Grid roller: The roll surface is made of cast steel with grid or mesh. They are particularly effective on granular soils to compact 6 to 8 inches to up to 18 inches on rock fills. It is an excellent compaction machine for rock fills as it crushes the rocks with the help of mesh and crushed particles fill the voids as it moves forward. 3. Vibratory: Rotating eccentric shaft of the roll or wheel provides vibratory action. At the point of resonance, the vibration of the soil is added to the compactor amplitude. At this point of frequency, the amplitude is maximum. This frequency is approximately equal to the natural frequency of the vibrator and the soil at contact area. Therefore the, compactor operating frequency should be maintained at resonance or above for maximum performance. The effect of vibration on clay is less than on sand. Dynamic force created by a vibrator’s mechanism can be calculated from the following calculation; F = 0 . 000341 WRN

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Where, F = Dynamic force in pounds W = Weight of eccentric mass in pounds R = Radius from center of eccentric mass to center of rotation in feet N = Rotation speed in revolutions per minute From the above formula, it is seen that the dynamic force increases with the square of the frequency. Dynamic force combining with the static force of the roller provides the total striking force to the soil. Benford Pedestrian Single drum vibratory roller owned by the DOR provides 920 Kg of centrifugal force 3900 rpm and 65 cycles per second. This centrifugal force further provides 7,480 Kgs. of striking force at contact soil. A vibratory compaction has the following advantages over the conventional compaction. a. Light weight and smaller towing unit. b. Better mobility c. Less expensive d. Effective to greater depths. 4. Smooth Steel Drum: These rollers are strong enough to crush the aggregate on the surface of asphalt lift. If adequate compaction is not achieved the roller is loaded with extra loads (sand or water ballast). Major disadvantage of this type of roller is that during compaction sometimes it produces bridging of the material being compacted. The bridging effect leaves voids and results in non-uniform compaction. A steel roller is basically slow, does not search out soft spots. These days, it is rarely used on earth fills and often used on asphalt surfaces. 7


5. Pneumatic Roller: These rollers are used to compact mainly bituminous road construction. They provide more uniform compaction effect than steel roller, as there is no bridging effect due to smaller tyre width. It has horizontal compaction forces in addition to the normal vertical compaction force. These horizontal compaction forces work not only in the direction of travel, but also across the machine. These various compaction forces thus are able to move materials in all directions. The effect of these forces supplemented by the elasticity of the rubber tyres provides a “Kneading effect” and results in superior compaction. The contact area can be increased or decreased by variation of tyre air pressure to have different compaction pressure on the material.

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Construction Equipment Used in Road Construction

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