The type of Equipment to be used for a specific project depends on the scope of the project and is executed by a contractor. It is always the choice of contractor to use suitable equipment for every project.
It involves Procurement cost and Operating cost
Procurement Cost: It includes the cost price of the equipment, interest on money invested in the purchase, taxes paid and insurance cost.
Operating Cost: It includes the cost of investment, depreciation, major repair, fuel and lubricants, labour, servicing and field repairs.
Types of Equipment
For any building project, the selection of equipment depends on the magnitude of the building project i.e., a single unit, multi-storeyed building, housing, complex or others. The type of equipment can be purchased, rented or contracted for the work according to the project size and other particulars.
A brief description below about the types of equipment needed for a building project:
Based on different field conditions earthwork and moving equipment are available which are discussed below.
Excavators are digging machines. These are of mechanical or hydraulic types. Hydraulic excavators have more advantages, which can be fitted with various multi-purpose attachments for various earth moving works.
Excavators are of four types, i.e., crawler-mounted excavator, truck-mounted excavator, self-propelled excavator, and excavator mounted on barge or rail.
It is a specific type of excavating machine fitted with a short length boom and working with forward strokes. They are available in four different front-end attachments.
Dipper Shovel: The dipper shovel or power shovel is the most popular of the shovel excavator consists of a boom, dipper stick, the bucket and the mechanism of operation. These are used for digging hard rock in quarries or ores in mines, in which digging is done above the machine level.
Drag Shovel or Hoe: It is also called as a Pull shovel, consists of a shovel boom, jack boom, and a stick for a dipper shovel. The digging mechanism of this machine resembles an ordinary garden hoe.
These machines help for digging below the machine level, particularly while digging for trenches, footings, basements, hard materials, providing close trimming, and to dumb excavated materials at a short distance.
Dragline: This machine consists of a boom (similar to that of a crane boom), a bucket, a fairlead and hoist, dump and drag cables. They have three types of buckets, light, medium and heavy, which are used depending on the nature of the material.
A dragline can dig and dump over a longer distance, can also handle digging of underwater excavation while stationing the machine on a firm soil away from the location of the pit. This machine can dig below the track level and can handle soft materials comfortably.
Clamshell: It consists of a crane boom with a special type of bucket. Its applications are widely used where the digging or dumping vertically is needed, digging of trenches, for loading materials in a bin or a stock pile, and for accurate dumping of materials.
It is multi-purpose equipment which can be used for different purposes with some modifications. It is important equipment on a construction project, basically a scraping and pushing unit. These can be used to haul up to 100 m distance and are available as angle dozer, tilt dozer, tree dozer, and push dozer.
A tractor is a multi-purpose machine, comes in the varied type of light model to heavy model. Heavy model is an important piece of equipment which is indispensable on all important projects, equipped with several special rings used for earth moving works.
These are of two types, wheeled tractors and crawler tractors. The wheeled type is used for light and speedy jobs, and for all practical earth moving jobs including nipping and dozing. The crawler tractors are rugged machines which are used for heavy duty work.
It is a device used for loading or finishing earthwork and also sometimes for mixing gravel, making windows and trimming slopes. There are two types of graders, towed and motorised.
Scrapers are designed to dig, load, haul, dump and spread. It does multiple works, also called a carry all.
A scraper is provided with a bowl, apron, ejector and a hydraulic system which comprises of digging or loading, transporting and unloading.
It is a machine in which a bucket is attached to the arms and capable of being raised, lowered and dumped through mechanical or hydraulic controls.
There are two types of loaders, crawler loaders and wheeled loader and are used for handling coal, sugar, sand, salt, stone, etc., to earth moving and digging works.
Trenchers are used for excavating trenches or ditches of variable width and depth. Wheel trenchers are the common type in trench excavator. The selection of trenchers depends on various factors, i.e., depth and width of the trench, type of soil, disposal of excavated earth, ground water position, and the nature of the job.
Groundwater and seepage control needs a most significant consideration in the construction and can be controlled depending on the geological conditions and characteristics of the soil. Below are some of the de-watering methods:
Open Sumps and Ditches: The attribute of the method is a sump below the ground level of the excavation at one or more corners or sides.
Well-Point Systems: These systems are very effective in solving subsurface water problem on construction sites. They are used to provide dry work areas below the water table for works like:
Foundation works - buildings, bridges, dams and dry dock.
Trench works - buildings, bridges, dams and dry dock.
Tunnel works - subway constructions.
Deep-well Drainage: The deep wells are installed by sinking a cased borehole having a diameter of about 300 mm larger than the well casing. The diameter of the latter depends on the size of the submersible pumps. The advantage of the system is that it can be installed outside the zone of construction operation and drainage is effected to the depth of excavation.
Vacuum De-watering System: A vacuum de-watering system consists of well or well-points with the screen and riser pipes.
This method is applicable for fine-grained soils. It is not a general pumping method but collecting the water through some process to a well and pumping out.
This method is used only when other methods fail as the cost of installation and maintenance are very high.
Elimination or reduction of ground water by
- Cement Grouting
- Displacement grouting
- Chemical consolidation
It is the process by which particles are packed closely together by reducing air void content.
Mechanical Forces: These forces may be applied by the following ways, i.e., by rolling, by kneading, by vibration and by ramming.
Rollers: Different types of rollers are used, Smooth-Wheeled rollers, Sheepsfoot rollers, Pneumatic-tyred rollers, and Tandom Compactors.
Pile Driving Equipment
Piles are generally classified as bored piles or driven piles depending on the method of installation.
Driven piles are manufactured in special lengths with materials like wood, concrete, steel and sometimes with a composite section of wood and steel, wood and concrete or steel and concrete. Sheet piles are also driven piles, may be wood, concrete or steel.
Pile Driving process consists of lifting the pile into position, holding it and driving it to refusal or a desired depth.
Components of Equipment
Pile Driving equipment comprises of the following components:
- Driving Rigs
- Guiding leaders
- Pile hammer with Accessories
- Additional aids for pre-boring and jetting
- Boiler for steam raising or air compressor
Pile driving hammers impart energy required to drive the pile into the soil. Hammers are classified as follows:
- Drop hammer: It is the simplest form of a hammer which does not use any external source of power.
- Single Acting Hammer: The functioning of single-acting hammer differs from drop hammer only in the manner of the lifting of the ram after each blow. The operation of this hammer costs less compared to a double acting hammer, but its speed is slower.
- Double-acting hammers
- Differential-acting hammers
- Diesel hammers
- Hydraulic hammers
- Vibratory hammers
- Sonic hammers
Moving and Hosting Equipment
The following movement devices are used in construction to shift materials from one place to another.
Vertical Movement Devices like Block and Tackle, Winch, Hoist and Elevators.
Horizontal Movement Devices like Hand Trucks, narrow-gauge Rail Road, Tractors, Trailers and Skids.
Combined Devices: These devices comprise the actions of lifting, lowering or transportation, devices like Chute, Lift truck, Forklift truck, Cranes, and Conveyers.
Cranes are electrically or diesel operated equipment used to lift and move heavy materials and machinery. They are classified as - Derrick cranes, Tower cranes, Pillar cranes, Overhead or gantry cranes, Self-propelling boom cranes and Crane trucks.
Hauling of materials or machines between sites can be time-consuming, expensive and unproductive. Movement of materials within a short distance can be done by using any of the movement-equipment.
Transport equipment such as Lorries, trucks, rubber-tire tractors with wagons or crawler tractors with wagons are usually used for transportation between sites of men, materials and machinery.
Trucks are essential equipment on any construction project available in various sizes and shapes.
Dump Trucks are fitted with automatic unloading devices, in which loading is done either by loading shovels or loaders.
Dumpers are trucks with special pneumatic wheels and capable of moving at high speeds having short chassis and strong dumping bodies.
Trailers are carriages hauled by power units such as tractors or trucks available in two types i.e., full trailer or wagons and semi-trailers.
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