UNIT V

PART A

1. What are the factors influencing compaction? (N/D 16)

The factors which influence compaction are: static weight ,number of vibratory drums, roller speed, drum diameter, frequency and amplitude relationship between frame and drum weight driven or non driven drum centrifugal force and total applied force

2. What are the types of dredgers? (N/D 16)

Dipper dredger, Ladder dredger and Suction dredger

3. Name the equipment’s used for earth moving operations. (M/J 16)

Excavators

Bulldozers

Skid steer loaders

Motor graders

Trenchers

4. Define compaction (M/J 16)

Compaction is defined as the process of densifying or increasing the unit weight of a soil mass through the application of static or dynamic force, with the resulting expulsion of air.

5. Give a list of construction equipments needed in the construction of tall structures. (M/J 12) Mobile crane, Tower crane, Chain Hoist, Winch Hoist, Lift crane, Hydraulic crane.

6. What are the types of equipments used for trenching and tunneling? (M/J 12) Trenching: Wheel trenches, Ladder type trenches Tunneling Tunnel Boring machine

7. Name the equipments used for volume batching (N/D 11)

The equipments used for volume batching are aggregate feeders, cement silo, water measuring device

and mixing unit

8. What are the various types of conveyors? (A/M 10)

The various types of conveyors are: belt conveyor, roller conveyor, chain or cable conveyor,pipe line conveyor, screw conveyor and elevating conveyor.

9. What are the advantages of using belt conveyors? (N/D 10)

The advantages of using belt conveyors are: It is capable of handling light or heavy, fine or coarse, wet or dry material. It can handle, thousands of tons of material per hour for several kilometers. It can handle not materials up to 1600c. It operates without noise.

9. What are the factors influencing compaction? (N/D 16)

The factors which influence compaction are: static weight, number of vibratory drums, roller speed, drum diameter, frequency and amplitude relationship between frame and drum weight driven or non-driven drum centrifugal force and total applied force

10. Name the equipments used for volume batching (N/D 15)

The equipments used for volume batching are aggregate feeders, cement silo, water measuring device and mixing unit

11. What are the various types of conveyors? (N/D 13)

The various types of conveyors are: belt conveyor, roller conveyor, chain or cable conveyor, pipe line conveyor, screw conveyor and elevating conveyor.

12. What are the advantages of using belt conveyors? (N/D 12)

The advantages of using belt conveyors are: It is capable of handling light or heavy, fine or coarse, wet or dry material. It can handle thousands of tons of material per hour for several kilometers. It can handle not materials up to 1600c. It operates without noise.

13. What is a tractor? Mention its types?

Tractor is earthmoving equipment which converts engine energy into tractive energy. The two types of tractors are crawler or tract type and wheel or pneumatic type.

PART B

1. Explain the various equipment’s for pile driving. (N/D 16), (M/J 12) (N/D 15)

Pile Driving Equipment:

Piles are installed by a special pile driving device known as a pile hammer. The hammer may be suspended from the boom of a crawler crane, supported on a large frame called a pile driver or carried on a barge for construction in water.

In all cases, the hammer is guided between two parallel steel members called leads. The leads may be adjusted at various angles for driving vertical and batter piles.

Types of Hammer:

Several types of hammers are in use and each of which are different sizes. The hammer types are:

1. Drop hammer:

The drop hammer in the pile driving equipment consists of a heavy ram in between the leads. The ram is lifted up to a certain height and released to drop on the pile. This type is slow and therefore not in common use. It is used in the cases where only a small number of piles are driven.

2. Single acting hammer:

In a single acting hammer a heavy ram is lifted up by steam or compressed air but dropped by its own weight. The energy of a single acting hammer is equal to the weight of the ram times the height of fall.

3. Double-acting hammer:

The double-acting hammer employs steam or air for lifting the ram and for accelerating the downward stroke. The energy of a double-acting hammer is equal to the (weight of the ram I mean effective pressure I the effective area of ram) 1 times the height of fall.

4. Diesel hammer:

The diesel hammer is a small, light weight and highly mobile. They use gasoline for fuel. To start the operation, the ram is raised, and the fuel is injected. As the ram is released, the ram falls and compresses air and fuel. The air and fuel becomes hot because of the compression and the air-fuel mixture is ignited. The resulting explosion

1. Advances the pile and 2. Lifts the ram. If the pile advance is very great as in soft soils, the ram is not lifted by the explosion sufficiently to ignite the air-fuel mixture on the next cycic, requiring that the ram be again manually lifted.

5. Vibratory hammer:

The principle of the vibratory driver is two counter-rotating eccentric weights. The driving unit vibrates at high frequency and provides two vertical impulses, one up and one down. The downward pulse acts with the pile weight to increase the apparent gravity force. These hummers have reduced driving vibrations, reduced noise, and great speed of penetration.

Hammer Selection:

Generally the size of hammer is more important factor than type of hammer. A heavy pile should be driven by a heavy hammer delivering large energy. Preferably the weight of HKjmcr should beat ^H HB1 the total weight of the pile and the deriving energy should be at Hpiie foot-pound for each pound of pile weight. Each type of hammer has its use under suitable conditions, The advantages and disadvantages of cach type are summarized below:

Single-acting hammer :

They arc advantageous when driving heavy piles in compact or hard soils; the heavy ram striking at - tow velocity produces least damage due to impact. The disadvantages arc low driving speed and large headroom requirement.

Double-acting hammer:

They are generally used to drive piles of light or moderate weight in soils of average resistance against driving. This type of hammer can drive piles at fast speed, requires less headroom and can be used to extract piles by turning them [i.e. the double-acting hammer] upside down.

Diesel hammer:

They are similar in application as double-acting hammers, but driving may become difficult in extremely soft ground.

Vibratory hammer:

They have fairly good results in silty and clayey deposits. They are used in heavy clays or soils with appreciable numbers of boulders. See above for other advantages.

Hammer Type Efficiency (ɳh)

Single and double acting hammer 0.7 - 0.85

Diesel hammers 0.8 - 0.9

Drop hammers 0.7 - 0.9

2. Mention the various types of compaction equipment. Mention their uses (N/D 16) (M/J 15) (N/D 12)

There are different types of rollers and other soil compaction equipments available. Use of these compacting

machines depends on soil types and moisture conditions.

Different Types of Soil Compaction Equipments:

The soil compaction equipments can be divided into two groups:

1. Light soil compacting equipments

2. Heavy soil compacting equipments

1. Light Soil Compacting Equipments:

These equipments are used for soil compacting of small areas only and where the compacting effort needed

is less. Below are light equipments for soil compaction:

(i) Rammers:

Rammers are used for compacting small areas by providing impact load to the soil. This equipment is light

and can be hand or machine operated. The base size of rammers can be 15cm x 15cm or 20cm x 20cm or

more.

For machine operated rammers, the usual weight varies from 30kg to 10 tonnes (6 lbs to 22000 lbs). These

hammers with 2- 3 tonnes (4400 to 6600 lbs)weights are allowed to free fall from a height of 1m to 2m (3ft to

7ft) on the soil for the compaction of rock fragments.

Rammers are suitable for compacting cohesive soils as well as other soils. This machine in areas with

difficulty in access.

(ii) Vibrating Plate Compactors:

Vibrating plate compactors are used for compaction of coarse soils with 4 to 8% fines. These equipments are

used for small areas. The usual weights of these machines vary from 100 kg to 2 tonne with plate areas

between 0.16 m2 and 1.6 m2.

(iii) Vibro Tampers:

Vibro tampers is used for compaction of small areas in confined space. This machine is suitable for

compaction of all types of soil by vibrations set up in a base plate through a spring activated by an engine

driven reciprocating mechanism. They are usually manually guided and weigh between 50 and 100 kg (100 to

220 lbs).

2. Heavy Soil Compaction Equipments:

These compacting machines are used for large areas for use on different types of soils. The heavy

compaction equipments are selected based on moisture content of soil and types of soil. Following are

different types of these equipments:

I) Smooth Wheeled Rollers:

Smooth wheeled rollers are of two types:

Static smooth wheeled rollers

Vibrating smooth wheeled rollers

The most suitable soils for these roller type are well graded sand, gravel, crushed rock, asphalt etc. where

crushing is required. These are used on soils which does not require great pressure for compaction. These

rollers are generally used for finishing the upper surface of the soil. These roller are not used for compaction

of uniform sands.

The performance of smooth wheeled rollers depend on load per cm width it transfers to the soil and diameter

of the drum. The load per cm width is derived from the gross weight of the drum.

The smooth wheeled rollers consists of one large steel drum in front and two steel drums on the rear. The

gross weight of these rollers is in the range of 8-10 tonnes (18000 to 22000 lbs). The other type of smooth

wheel roller is called Tandem Roller, which weighs between 6-8 tonne (13000 to 18000 lbs).

The performance of these rollers can be increased by increasing the increasing the weight of the drum by

ballasting the inside of drums with wet sand or water. Steel sections can also be used to increase the load of

the drum by mounting on the steel frame attached with axle.

The desirable speed and number of passes for appropriate compaction of soil depends on the type of soil and

varies from location to location. About 8 passes are adequate for compacting 20 cm layer. A speed of 3-6

kmph is considered appropriate for smooth wheel rollers.

Vibrating smooth wheeled rollers

In case of vibrating smooth wheeled rollers, the drums are made to vibrate by employing rotating or

reciprocating mass.

These rollers are helpful from several considerations like:-

(i) Higher compaction level can be achieved with maximum work

(ii) Compaction can be done up to greater depths

(iii) Output is many times more than conventional rollers

Although these rollers are expensive but in the long term the cost becomes economical due to their higher

outputs and improved performance. The latest work specifications for excavation recommends the use of

vibratory rollers due to their advantage over static smooth wheeled rollers.

(ii) Sheepsfoot roller Roller:

Sheepsfoot rollers are used for compacting fine grained soils such as heavy clays and silty clays. Sheepsfoot

rollers are used for compaction of soils in dams, embankments, subgrade layers in pavements and rail road

construction projects.

Sheepsfoot rollers are of static and vibratory types. Vibratory types rollers are used for compaction of all fine

grained soils and also soil with sand-gravel mixes. Generally this roller is used for compaction of subgrade

layers in road and rail projects.

As seen in picture above, sheepsfoot rollers consist of steel drums on which projecting lugs are fixed and can

apply a pressure upto 14kg/sq cm or more. Different types of lugs are namely spindle shaped with widened

base, prismatic and clubfoot type.

The weight of drums can be increased as in the case of smooth wheeled rollers by ballasting with water, wet

sand or by mounting steel sections.

The efficiency of sheepsfoot rollers compaction can be achieved when lugs are gradual walkout of the roller

lugs with successive coverage. The efficiency is affected by the pressure on the foot and coverage of ground

obtained per pass. For required pressure and coverage of ground, the parameters such as gross weight of

the roller, the area of each foot, the number of lugs in contact with the ground at any time and total number of

feet per drum are considered.

The compaction of soil is mainly due to foots penetrating and exerting pressure on the soil. The pressure is

maximum when a foot is vertical.

(iii) Pneumatic Tyred Rollers:

Pneumatic tyred rollers are also called as rubber tyred rollers. These rollers are used for compaction of

coarse grained soils with some fines. These rollers are least suitable for uniform coarse soils and rocks.

Generally pneumatic tyred rollers are used in pavement subgrade works both earthwork and bituminous

works.

Pneumatic rollers have wheels on both axles. These wheels are staggered for compaction of soil layers with

uniform pressure throughout the width of the roller.

The factors which affects the degree of compaction are tyre inflation pressure and the area of the contact.

The latest rollers have an arrangement to inflate the tyre to the desired pressure automatically. The total

weight of the roller can be increased from 11.0 tonne to 25.0 tonne or more by ballasting with steel sections or

other means.

(iv) Grid Rollers:

Grid rollers are used for compaction of weathered rocks, well graded coarse soils. These rollers are not

suitable for clayey soils, silty clays and uniform soils. The main use of these rollers are in subgrade and sub-

base in road constructions.

As the name suggests, these rollers have a cylindrical heavy steel surface consisting of a network of steel

bars forming a grid with squire holes. The weight of this roller can be increased by ballasting with concrete

blocks.

Typical weights vary between 5.5 tonnes net and 15 tonnes ballasted. Grid rollers provide high contact

pressure but little kneading action and are suitable for compacting most coarse grained soils.

(v) Pad Foot / Tamping Rollers:

These rollers are similar to sheepsfoot rollers with lugs of larger area than sheepsfoot rollers.

The static pad foot rollers also called tamping rollers have static weights in the range of 15 to 40 tonnes and

their static linear drum loads are between 30 and 80 kg/cm. These rollers are more preferable than

sheepsfoot roller due to their high production capacity, and they are replacing sheepsfoot rollers.

The degree of compaction achieved is more than sheepsfoot rollers. The density of soil achieved after

compaction with this roller is more uniform.

These rollers operate at high speeds, and are capable to breaking large lumps. These rollers also consists of

leveling blades to spread the material.

Pad foot or tamping rollers are best suitable for compacting cohesive soils

3. Mention the various types of earthwork equipment. Mention their uses. (M/J 16), (M/J 12)

Excavator

An excavator is a construction vehicle used to excavate or move large objects. An Excavator is basically made up of 2 parts: a driving base associated a powerful boom arm with an attachment designed for excavating. The operator sits within a small cab connected to the base and controls the arm. The excavator uses a Hydraulic system to generate a Hydraulic force to control the mechanical arm of the machine. It also uses a chain wheel system for it’s movement.

Excavators are been used in large and small scale constructions. They are used for small housing projects to do a cut and fill, used in road construction, used in marine structures to place armors and large rocks, and also been used in larger sites to excavate, move construction material, remove construction waste etc….. There are several types of excavators which are classified on use, brand and purpose.

Usage of Excavator in Construction.

The excavator probably is the most commonly used machine in the Construction Industry. There are many uses of an Excavator.

Digging of trenches, holes, foundations

Demolition

Material handling

General grading/landscaping

Brush cutting with hydraulic attachments

Forestry work

Lifting and placing of pipes

Mining, especially, but not only open-pit mining

River dredging

GRADER

A grader is a construction machine with a long blade used to create a flat surface. It is commonly called in names such as road grader, a blade, a maintainer and motor grader,

Graders Used in construction Graders are mostly been used in road construction for construction and maintenance of dirt roads and gravel roads. The grader typically consist of three axles, with the engine and cab situated top, the rear axles at one end of the vehicle and a third axle at the front end of the vehicle, with the blade in between.

In the construction of paved roads they are used to prepare the base course to create a wide flat surface for the asphalt to be placed on. They are also used to set native soil foundation pads to finish grade prior to the construction of large buildings. Many countries use grader for the flatting process that is done before the placing of Asphalt. Graders too have various types; some consist a large fork front, and some consist of a flat blade front, which vary from different sizes.

LOADER

A loader is a heavy equipment machine frequently used in construction industry, mainly used to Load material (such as demolition waste, feed, gravel raw minerals, used material, rock, and plywood) into or onto another type of machinery (such as a dump truckload).Loaders have a very higher productivity and a lower maintenance cost unlike most of the other large scale construction machines.The Loader has a large bucket with a shorter moving arm. Large quantities of material such as soil, construction material, etc can be moved from this.The loader consist of four large wheels for its movement.Loaders are best suited for earth moving, road construction, agricultural purposes, and also in large and small scale constructions which include marine structures. Loaders too are available in various types based on it’s use and brand. Similar names : Front end loader, bucket loader, scoop loader, or shovel.

Loader in construction

Loading materials into trucks.

Usage of Loaders in construction

Laying pipe

Clearing rubble

Moving of Construction waste and other materials

Small excavations

Bulldozer A bulldozer is a crawler (continuous Tracked tractor) with a substantial metal plate used (known as blade) fitted to push large amounts of soil, sand, dirt or other materials when construction or remodeling and usually push on the back with a claw mechanism (Known as ripper) to loosen densely-compacted materials.

TRENCHERS It is sometimes called as Ditchers or Trenches, are similar to excavators in the sense that penetrate the soil, break soil and rock, and from the earth. They differ from excavators in that the soil is removed in one continuous movement. Digging trenches for pipes used specifically for, but other machines have been improvised in the past in order to serve this purpose.

Trenches in construction

Trenchers can come in two types Ladder trenchers

Wheel trenchers can dig trenches at speeds that other machines cannot compare to.

SCRAPERS

The scraper is a large piece of equipment used in mining, construction, agriculture and other earth moving applications.

Scraper used in construction

When the hopper is full it is raised, and closed with a vertical blade (other name : apron). The scraper can carriage its load to the fill area where the blade is raised, the back panel of the hopper, or the ejector, is hydraulically pushed forward and the load tumbles out. Then the empty scraper returns to the cut site and repeats the cycle.

4. Describe in detail the various equipments used for compaction, batching. [M/J – 10] [N/D – 12]

Concrete production equipment

According to specific conditions on the construction work, the needs of the user, the environmental and security conditions or economic factors, the concrete can be produced in the following categories related to location of production:

• Concrete plant in relative distance of the construction work;

• Concrete plant in the construction work;

• Concrete mixers on-site with small and medium dimensions.

There are no significant technical differences in terms of production of concrete, in relative distance of the concrete plant and construction work and the concrete plant at construction work. The relevant selection criteria for concrete production equipment, which can be divided in two distinct but interrelated levels are: − Selection criteria regarding the location of concrete production; − Selection criteria regarding technical aspects of each equipment comparable between each other. In both cases, the decision is based in the required concrete quantity, concrete quality, concrete type, costs and deadlines. The aspects related to equipment maintenance and safety of are very important because the concrete production equipment are also working machines with associated costs and dangers, which if not treated could cause injuries.

Description and characterization of concrete production equipment

Concrete production equipment on concrete plant.

The concrete mixers are made of high resistance steel drums or tanks, especially on the inside where is coated with special steel plates. Drums or tanks are available in several dimensions. The dimension of the drum is the factor that determines the capacity of the mixer in quantitative terms. Inside are equipped with mixing paddles or blades on the shaft power transmission placed in arms that rotate around that axis. The power transmission axes can be in vertical or horizontal axis and there may be more than one mixer shaft. The introduction of relative motion with the right intensity and the proper proportion of constituents are used to reach to adequate concrete mixture. Regarding the concrete production in concrete plant, there are two major categories of concrete mixing, these groups can be used for the classification of concrete mixers:

• Simple production mixers;

• Continuous production mixers.

The simple production mixers have the characteristic of producing one mixture at the time, therefore have to be completely emptied after each mixing cycle (and cleaned if possible) and recharged with materials for the next mixing. In terms of production capacity per cycle can reach from 1 m3 to 6 m3 . The concrete mixer can be tailor-made for special cases. Within the category of simple production mixers still exists the reversible mixer that can achieve capacities of 9 m3 per cycle. The simple production mixers has always been the most used, they exists in several types depending of the direction and number of rotation axes. The continuous production mixers as the name implies, are continuously fed with the constituents of concrete at the same

rate at which concrete is discharged. They are generally composed by not tilting drums and have blades or paddles rotating axis or axes in case of the mixer be a twin shaft mixer. The continuous production mixers are used only when large amounts of concrete are required and when the required concrete quality is weaker, is the case of paving or tops of dams. The main selection criteria to consider in selection of the concrete production equipment in plant are: − Required concrete volume; − Required concrete quality; − Time and costs; − Mixing speed; − Level of automation; − Number and type of mixing paddles (mixing system). Mixing systems are suitable for certain types of concrete, for example, concrete mixers with satellites mixing system are suitable for dry high-strength concrete usually suitable for precast concrete elements. A good selection of mixing equipment is crucial to the success of the construction work, because it determines the compliance or non-compliance with deadlines, costs and quality of concrete.

Concrete production equipment on-site

The portable concrete mixers can be electricity, petrol or diesel powered, with capacities of mixing drum ranging from 100 liters to 750 liters. The concrete mixers used in the current construction works are, based on the needs of each project, the mixers of 180 liters, 260 liters and 400 liters. There are many different types of portable concrete mixers ranging in characteristics such as capacity, number of cycles/hour, power supply and mobility. This equipment is characterized by its " portability " - i.e., ease of movement and deployment- this is due to their small size and weight. It can be easily transported from place to place in the same construction work.

1. Various Equipment’s for mixing of concrete. [M/J – 10] [N/D14]

The mixers can be classified according to the technical aspects of overall operation, namely:

• Mobility; • Discharge method; • Mixing system; • Power supply.

ployed and easily moved and handled. In terms of location in the jobsite it is, whenever possible, close to raw material constituents of concrete, and near the discharge locations, since the drums must be loaded before each discharged immediately after mixing. A concrete mixer with great advantages in terms of work mobility is the mini-truck mixer. The discharge method is also important because it determines the placement of concrete in its final position, and a defective discharge method can lead to loss of properties required for concrete, like the occurrence of concrete segregation The mixing system is important because there are concrete with characteristics that are only possible to reach by a specific blending method. The type of power supply is an aspect that can be important depending on the availability of energy resources on site. The main technical aspects (selection criteria) for portable concrete mixers are:

− Mobility; − Mixing capacity; − Mixing speed; − Mixing Method; − Discharge method; − Concrete Properties

Maintenance and safety of concrete production equipment

Regular maintenance is essential for the reliability and service life of concrete production equipment. The proper maintenance also helps to eliminate the hazards associated to workplace due to the typical supervision activities of the maintenance processes. Lack of maintenance or improper maintenance can cause dangerous situations, accidents and health problems. So there is a direct link between maintenance and safety. This type of equipment has a high mechanical rotation operation. This rotational movement and easy access to input and output local of concrete feeding devices makes it dangerous process. The active

maintenance of this equipment is considered of high risk and must be performed safely. Before any maintenance the equipment must be disconnected from any power source.

Concrete transportation equipment

The process of transporting concrete is an extremely important and determining step for the success of a construction work. It is necessary to run an effective and efficient transport to ensure that the concrete reaches its final destination in the prescribed conditions, i.e. without losing properties inherent to its fresh state and later its hardened state The transportation of concrete shall be done with equipment suitable for the type of concrete, the distance between the place of production and the jobsite, the type of route, the weather and other conditions that could be predicted, such as traffic or times hold due to other deliveries of concrete. The perishable material such as concrete requires careful planning with respect to transportation and placement so the discharging process should not coincide with the arrival of other concrete fillers. The time factor is crucial, it is necessary to be a preparation even in the level of correction of unexpected equipment failures, for example, a flat tire can be sufficient to delay the delivery. Currently there are several fleet management software that aids the fleet management and even the preventive and corrective maintenance. Given the importance of the transportation process it is also important to define selection criteria, with the objective of adapting the equipment to the construction work and to the type of concrete. The aspects of selection are related to transportation capacities, required concrete quality, time and costs.

Description and characterization of concrete transportation equipment

Within the concept of transportation the equipment used for this purpose is the concrete mixer truck. The concrete mixer truck is characterized by being transport equipment and simultaneously a mixing equipment, the mixing process is usually useful to maintain the consistency of concrete. The concrete mixer truck is a vehicle with a drum/mixing tank mounted on its chassis or on semitrailer, are generally mounted with hydraulic pump piston with variable displacement and fixed hydraulic motor. Drums are available with capacities varying from 1 m 3 to 12 m3 , and its interior is controlled in terms of temperature, humidity, pressure and consistency. The rotation speed of the drum is controlled and is also a very important factor for the mixture control. The mixing drums are fitted with helical blades that are an integral part of the drums and are responsible for mixing the concrete when revolve around one direction and are responsible for unloading and cleaning when turning in the reverse direction. These blades are made of highly resistant steel because they are in permanent contact with the concrete. The selection criteria for concrete transportation equipment are very important to ensure the success of the construction work, being necessary to consider the transport equipment taking into account the location of the construction work, its size required properties for concrete and deadlines to meet. Thus the selection criteria should include: − Required quantity and quality of concrete - This criteria is important to determine the capacity of the concrete mixer truck and/or the type and the number of trips required for completion of the concrete placement; − Use method - this relates hypothesis of hire only concrete mixer trucks or concrete mixers truck for transportation and production or concrete truck mixers with pump system.

Concrete placement equipment

The process of concrete placement in the jobsite - concreting - is one of the most important in the concrete cycle because if the requirements and rules are not followed all the work so far can be putted in question even if the concrete has left the production in excellent condition and transportation has been successful. This stage is therefore one of the most demanding in terms of supervision. It is understood by concrete placement on-site, the unloading of concrete to its final position, compacting and finishing. The finishing of the concrete is done through leveling, grinding and possible application of products in its surface layer. The main ways of

placing concrete in its final position are: − Discharged by the concrete mixer truck in to its final position; − Through concrete gutters discharge; − Discharged by buckets, after reception of concrete mixer truck and crane transportation; − Pumped using concrete pumps and discharged in its final position by means of piping.

6. Explain in detail, the factors governing the selection of equipment for earthwork. (N/D 15) (M/J 14)

One of the problems encountered by a contractor as he plans to construct a project is the selection of the most suitable equipment to be used. For a beginner contractor, he cannot spend all the money for equipment in a particular investment. A contractor can never afford to own all types and sizes of equipment. A contractor does not have to pay for the construction equipment but it must pay for itself by earning for the contractor more money than it costs.

Factors Affecting the Selection of Construction Equipment 1. Standard type of Equipment. There is no such definition of standard type of equipment. An equipment maybe standard to one contractor but may not be to another. It depends on the operations of a contractor/company. 2. Special Equipment. One definition of special equipment is one that is manufactured for use on a single project or a special type of operation 3. Replacement of Parts. One factor in the Selection of branded equipment is the availability of replacement parts. When buying equipment, spare parts must be readily available or could be easily purchased. A truck with a broken axle is useless until the axle is replaced. A contractor should know where to obtain spare parts for his equipment, if not, then it may be wise to purchase or rent another equipment. 4. Cost of Owning and operating construction equipment. There is no exact method of determining the probable cost of owning equipment. Carefully kept records should give information as a guide as to the type of equipment you need to purchase. The number and the kind of projects a contractor is involved in should indicate what kind of equipment he has to purchase. 5. Economic life of construction equipment. The owner of the construction equipment should be interested in obtaining the lowest possible cost per unit of production. In order to accomplish this objective, he must follow an informed program of equipment replacement. How many years will he use his equipment?? Do his maintenance costs warrant the operation of the equipment or is there a need to dispose the equipment and buy another on?? The owner must consider all the costs related to the ownership and operation of the equipment. The costs to be considered are: depreciation and replacement, investment, maintenance and repairs, downtime, obsolescence. An analysis of the effect which hours of usage will have on each of these

costs will establish the time at which a machine should be replaced. 6. Sources of Construction Equipment. Contractors are frequently concerned about whether to purchase or lease construction equipment. Under certain conditions, it is financially advantageous to purchase whereas under the conditions it is more economical and satisfactory to rent it.