CE Lec Slides, Const Machinery.pdf

CONSTRUCTION ENGINEERING CE-375
SE SHAHID HUSSAIN
Construction Machinery

Need for Construction Equipment
•To reduce the duration of the process
•To reduce costs
•To reduce (heavy) manual work
2

Construction Machines Choice
 The aim of the machine; the work to carry out –
the planned technologies
 The material / elements to work with
 The quality to achieve
 The capacity needed
 The conditions at the site
 The schedule
 The budget
3

Types of Machines
4
Earthwork Transportation
Concrete equipment
Lifting

Earthwork Machines
5
Dozers, bulldozers Loaders

6
Scrapers Graders
Earthwork Machines

7
Excavators Power Shovel
Earthwork Machines

8
Dragline Clamshell
Earthwork Machines

Lifting Equipment
9
Mobile Crane Fixed Crane

10
Lifter Gantry
Lifting Equipment

Transport Equipment
11
Dump Truck Dump Truck

12
Pumps Transit Mixer
Transport Equipment

Concrete Equipment
13
Mixer Batching Plant

14
Transit Mixer Internal Vibrator
Concrete Equipment

15
External vibrator
Concrete
Spreader/Finisher
Concrete Equipment

Cranes
 A crane is a type of
machine, generally
equipped to lift and lower
materials and to move
them horizontally. It is
mainly used for lifting
heavy things and
transporting them to other
places
 It uses one or more simple
machine to create
mechanical advantage and
thus move loads beyond
the normal capability of a
man
16

Mobile Cranes
Crawler
Telescoping boom all-
terrain
Lattice-boom truck-
mounted
Rough-terrain
Modified cranes for heavy
lifting
18

Vertical boom arrangement
on a mobile crane
Mobile crane superstructure
mounted a top a tower
Vertical tower with a jib
Tower Cranes
19

 When repetitive lifting is involved the crane should be positioned for shortest
possible swing cycle to reduce cycle time. For heavy lifts, crane should be
positioned to lift over end of mounting where it has maximum lift capacity.
 Crane footing should be checked carefully before lifting capacity or near-
capacity loads. Ratings are based on firm, level footings.
 All overhead obstructions should be inspected carefully before moving a
crane or starting lifting operations. Machine should be located so as to avoid
any contact with power lines.
 In attaching loads, a secure hitch must be made and lift started when all
helpers a re in the clear.
 Operator should swing crane slowly enough to avoid excessive outward
throw of load and over swinging when machine stops. Crane work is similar
to moving a long pendulum, which can be controlled only in slow motion.
Fast swinging of crane loads will lose more time than it gains through loss of
control, and is very dangerous. A tagline device, similar to that used for
clamshell buckets, can be attached to loads to control outward swing.
Helpful Hints for Effective Crane Operations
21

 Loads should be placed on solid footings so they have no tendency to
overbalance when hitch is released.
 In figuring height of lift, the block, hook, and any sling-slack between hook
and load must be included. When making capacity lifts, the entire lifting
cycle should be calculated and planned before picking up load. It takes
less time and is much safer to check clearance and position than to lift
and try, then reposition and try again. With repetitive lifting, a planned
cycle is the best way to high production at low costs.
 Organize work for minimum travel time. All needed lifts possible in one
area should be completed before moving to another location.
 Booming up and down lengthens the cycle and should be avoided as
much as possible on repetitive lifting.
 With rubber-mounted cranes, outriggers should be securely set before
undertaking any near capacity loads. Footing under jacks must be level
and solid.
22

 Jerky operations on crane work should be avoided. It is hard on
cable and dangerous.
 Adding a jib to the boom increases the working range both
horizontally and vertically, but can reduce lifting capacity.
 With a given boom length, the steeper the working angle the shorter
the working radius. With each degree of boom movement to a more
vertical position, there is a corresponding degree of reduction in
boom radius-and a corresponding increase in lifting capacity.
 Level footing avoids swing "up or down hill,“ requires less power, is
faster and safer.
 When a heavy load is to be lowered from a high position (Example:
into a basement or hold of a ship), it is of prime importance that
adequate length of hoist cable is assured to facilitate full travel of
the block to the lowest point required
23

Excavator
 An excavator has been defined as a
power-driven digging machine,
usually mounted on crawler tracks
 The major types of excavators used
in construction include hydraulically
powered excavators and the
members of the crane-shovel family
 However, dozers and scrapers are
also capable of excavating soil and
rock
24

Usage of Excavators
• Digging of trenches, holes, foundations
• Material handling
• Brush cutting with hydraulic attachments
• Forestry work
• Forestry mulching
• Demolition
• General grading/landscaping
• Mining, especially, but not only open-pit mining
• River dredging
• Driving piles, in conjunction with a pile driver
• Drilling shafts for footings and rock blasting
25

Main Components of Excavator
27

Main Components of Excavator
28

Type of Buckets Attachments
29

Bucket Capacity
 Bucket payload can be
measured by volume or
weight
 Volume is typically stated
as struck measure of
loose volume meaning
that the material excess is
scraped off flush with the
top of the bucket.
 Heaped at a specific angle
of repose
31

Fill Factors
 The heaped capacity of a bucket or a bowl
can be calculated using the fill factor for
the type of soil that is moved or excavated
 Different soils have different fill factors.
Stickier soil has a greater fill factor,
therefore more can be heaped into the
bucket or the bowl. The amount of
moisture in the soil will influence the fill
factor.
 The average bucket payload equals the
heaped bucket capacity times the bucket
fill factor.
32

Excavator Load Capacity for
different boom and buckets
*Lifting capacity @ 20 ft.
t Lifting capacity @ 25 ft.
33

Bucket Payload
 An excavator’s bucket payload (actual amount of material in the
bucket on each digging cycle) is dependent on bucket size, shape,
and certain soil characteristics, i.e., the fill factor for that soil. Fill
factors for several types of material are listed below.
 Average Bucket Payload = (Heaped Bucket Capacity) x (Bucket Fill
Factor)
 The total amount of material carried by a bucket is the amount
inside the bucket plus the amount piled on top of it. This is called
the Heaped or Rated Capacity.
 The amount of material piled on top of the bucket, (heap), is
determined by the angle of repose of the material being handled.
 Angles of repose of 1:1 or 45° is taken
34

Excavator Production Estimate
 Depend upon
Bucket heap capacity Q in LCY
Fill factor F
Cycle time t in sec
Efficiency in min/hr E
Swell factor
 Production= x x
in BCY
35

Cycle Time for Typical Excavator
36

Example
 A crawler hoe having a 3.5 cy bucket is being considered
for use on a project to excavate very hard clay from a
borrow pit. The clay will be loaded into trucks having a
loading height of 9 ft 9 in. Soil-boring information indicates
that below 8 ft. the material changes to an unacceptable
silt material. What is the estimated production of the hoe
in cubic yards bank measure, if the efficiency factor is
equal to a 50-min/hour?
 Size of bucket, 3 1/2 cubic yard
 Bucket fill factor (Table), hard clay 80 to 90%; use
average 85%
37

Solution
 Typical cycle element times. Optimum depth of cut is 30 to 60%
of maximum digging depth (23 to 27 feet)
8/23 = 0.34 8/27 = 0.3 within limits
 Load bucket 7 sec
 Swing with load 6 sec
 Dump Load 4 sec
 Return swing 5 sec
 Cycle Time 22 sec
 Efficiency factor = 50 min/hr
 Swell factor = 35%
 Production= (3600x3.5x0.85/22) x (50/60) x (1/[1+0.35])
= 300 BCY/hr
 Check maximum height for loading= 21 to 22 ft available is ok
for dump truck height (21 ft > 9 ft 9 in. okay)
38

Dozer
39
 A bulldozer is a tractor unit with a
blade attached to its front. The
blade is used to push, shear, cut,
and roll material ahead of the
tractor.

Types of Dozers
Crawler (tracked)
Tractor
Wheeled Tractor
41

Use of Dozers
 Dozer machines are designed to provide
tractive power for drawbar work.
 Consistent with their purpose, as a unit for
drawbar work, they are low-center-of-gravity
machines. This is a prerequisite of an effective
dozer.
 The larger the difference between the line-of-
force transmission from the machine and the
line-of resisting force, the less effective the
utilization of developed power.
42

Type of Works
 Dozing
 Land Clearing
 Ripping
 Towing
 Assisting Scrapers
43

Rippers
44
 The ripper is the long
claw-like device on the
back of the bulldozer.
 Rippers can come as a
single (single shank
/giant ripper) or in
groups of two or more
(multi shank rippers).
Usually, a single shank
is preferred for heavy
ripping.

Grader
 Graders are multipurpose
machines used for
finishing and shaping
 This is a long tractor
driven piece of
equipment with a blade
mounted underneath
45

Graders
46
 A grader has a large blade used to create a
flat surface.
 Typical models have three axles, with the
engine and cab situated above 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.
 The grader's purpose is to "finish grade"
(refine, set precisely) the "rough grading"
performed by heavier vehicles such as
bulldozers.
 Graders can produce inclined surfaces and
cambered cross-sections for roads

Functions of Graders
 Graders are used
for
 Grading
 Shaping
 Bank sloping
 Ditching
 They are also used for
 Mixing
 Spreading
 Side casting
 Leveling
 Crowning
 General construction
 Road and runway
maintenance
47

Estimating Production
 No of Passes(P)
 Distance traveled in
each pass(D)
 Efficiency of grader(E)
 Grader speed(S)
 Effective blade width(W)
Proper gear ranges for
grader operations
50

Example
Maintenance of 5 miles of haul road requires cleaning the
ditches, and leveling and reshaping the roadway. Use an
efficiency factor of 0.60. Cleaning the ditches requires two
passes in first gear (2.3 mph); leveling the road requires
two passes in second gear (3.7 mph); and final shaping of
the road requires three passes in fourth gear (9.7 mph).
51

Example
A haul road of 1,500 ft requires leveling and
reshaping. Use an efficiency factor of 0.60. The
work requires two passes in second gear (3.7
mph) and three passes in third gear (5.9 mph).
(multiply mph by 88 to convert to fpm)
52

Example
 It is required to fine grade the sub-grade of a
roadway before proceeding to construct the sub-
base. Use an efficiency factor of 0.60. The grader
will be operated in second gear (3.5 mph) for this
work. The effective blade width per pass is 9 ft.
Estimate the production rate (area) for these
conditions.
Note: Typically, multiple passes are required to meet the specified grade
tolerance, which can accordingly reduce production.
Production area, is measures in Sy/hr = square Yard Area/hr
53

Loaders
 Loaders are used extensively in
construction operations to handle and
transport material, to load haul units, to
excavate, and to charge aggregate bins
at both asphalt and concrete plants.
 The loader is a versatile piece of
equipment designed to excavate at or
above wheel or track level.
 The hydraulic-activated lifting system
exerts maximum breakout force with an
upward motion of the bucket.
 Large rubber tires on wheel models
provide good traction and low ground-
bearing pressure.
 A wheel loader can attain high speeds,
which permits it to travel from one job
site to another under its own power.
54

Loader Types
 Classified on the basis of running gear, there are
two types of loaders:
 Crawler-tractor-mounted type
 Wheel-tractor-mounted type
 They may be further grouped by the capacities of
their buckets or the weights that the buckets can
lift.
 Wheel loaders may be steered by the rear wheels,
or they may be articulated.
 To increase stability during load lifting, the tracks of
crawler loaders are usually longer and wider than
those found on comparable-size tractors.
55

Shovels
56
Front shovels are designed to dig
above grade into the face of the
excavation, not to scoop at ground
level. These shovels typically
operate on tracks for better traction
when pushing the bucket into the
face to be excavated. The work
typically entails filling the bucket,
backtracking or positioning and
dumping the bucket contents into a
pile or a truck. Front shovels are
typically not very mobile and travel
distance be minimized.

Hauling Equipment
 The transportation of excavation, or hauling, is one
of the biggest jobs done in earth moving. A wide
range of equipment is available for transporting
excavated material, including dump trucks, wagons ,
scrapers, conveyor belts, and trains. Of these forms
of hauling equipment, trucks and wagons are most
widely used.
 Trucks are hauling units that provide relatively low
hauling costs because of their high travel speeds.
The weight capacity of a truck may limit the volume
of the load that a unit can haul.
58

Haulage
 Haulage Cycle
 Total haul unit cycle time is
found by summing the time
required for each of the
following components of the
haul cycle:
 Load-at the excavator and
loader
 Haul-from the loader to the
unloading site
 Dump-at the unloading site,
including maneuvering
 Return-travel back to the
loader
 Spot-move into loading
position at the loader
 Loading Time
 The time required to load a haul
unit may be estimated by
applying the appropriate one of
the following equations:
Haul unit capacity
 Loading time= ---------------------
Loader production
No of Haulers
Cycle time for Haulage
= ----------------------------
Loading time
60

Example
 If shovel production at a job is 305 BCY/hr and truck
transit time (cycle time less load time ) is 0.5 hr,
determine how many trucks having a capacity of 165
BCY would be required to fully service the shovel.
How many bank cubic yards per hour will be
produced by this combination . Take efficiency=0.75
 Load Time = 16.5/305 =0.054 hr
 Transit Time = 0.5 hr
 Truck Cycle time = 0.5 + 0.054 = 0.554 hr
 No of Trucks required = 0.554/0.054 = 10.3
 Expected production = 10 x 16.5 x 0.75 (efficiency)
 = 123.75 BCY
 For 11 trucks = 305x0.75
 = 229 BCY
61

Rollers
 A roller is a compactor type engineering vehicle used to compact
soil, gravel, concrete and asphalt in the construction of roads and
foundations and land fills.
 Compaction equipment must be matched to the type of material
being manipulated. Equipment manufacturers have developed a
variety of compactors that incorporate at least one of the compaction
methods and in some cases more than one into machine
performance capabilities.
62

Compactor
 Compaction equipment ranges from handheld
vibratory tampers (suitable for small or
confined areas) to large, self-propelled rollers
and high speed compactors (ideally suited for
large, horizontal construction projects).
 Types of Rollers
 Tamping rollers and Sheepsfoot rollers
 Smooth-drum vibratory soil compactors
 Pad-drum vibratory soil compactors
 Pneumatic-tired rollers
63

Tamping-Foot / Sheep-Foot Roller
 The self-propelled, tamping-foot roller has
feet that are square or angular and taper
down away from the drum.
 This roller compacts the material from the
bottom of the lift to the top, and walks out
after achieving the desired density.
 It is suitable for compacting all fined grained
materials, but is generally not suitable for
use on cohesionless granular materials.
 The lift thickness for the tamping-foot roller is
limited to 8 inches in compacted depth 17 January 2021
64

Smooth Wheel Rollers
 Widely used simple
rollers
 Work on static weight
 Used for compacting
granular bases,
bituminous pavements
65

Pneumatic Tired Rollers
 These rollers apply the principle of kneading
action to affect compaction below the surface.
 They may be self-propelled or towed.
 Pneumatics are used on small-to medium-size
soil compaction jobs, primarily on bladed
granular base materials.
 Small pneumatics are not suited for high-
production, thick lift embankment compaction
projects.
 Pneumatic tired rollers are also used in
compacting asphalt, chip seals, recycled
pavement, and base and subbase materials.
66

Special Compactors
Compaction Wheels
 Compaction wheel attached to an excavator
boom is often used to achieve compaction
when backfilling utility trenches.
 The feet on these wheels can be of either
the sheep-foot or tamping shape.
 The wheels are designed to compact all
types of soil.
 Changing from an excavator bucket to a
compaction wheel can be accomplished
quickly.
 Wheels are manufactured in sizes to fit 7- to
45-ton excavators
67

Special Compactors
Vibratory Plate Compactors
 Self-propelled vibratory-plate compactors are used
for compacting granular soils, crushed aggregate,
and asphalt concrete in locations where large
compactors could not operate.
 These gasoline or diesel powered units are rated by
centrifugal force, exciter revolutions per minute, depth
of vibration penetration (lift), foot-per-minute travel,
and area of coverage per hour.
 Many of these compactors can be operated either
manually as a walk-behind unit or by remote control
68

Special Compactors
Manually Operated Rammers
 Gasoline-engine-driven rammers are
used for compacting cohesive or mixed
soils in confined areas.
 These units range in impact from 300 to
900 foot-pounds (ft-lb) per sec at an
impact rate up to 850 per min, depending
on the specific model.
 Performance criteria include pounds per
blow, area covered per hour, and depth
of compaction (lift) in inches.
 Rammers are self propelled in that each
blow moves them ahead slightly to
contact a new area.
 Special compactor provide
adequate output if
 Lift thickness is minimal
(usually 3 to 4 in.),
 Moisture content is
carefully controlled, and
 Coverage are sufficient.
69

Lift Thickness
 The lift thickness to achieve required density will
vary with soil and compacter characteristics.
 For tamping foot rollers lift thickness should not
exceed roller feet.( 2 in)
 For smooth wheel rollers lift should be limited to 6
in.
 For Pneumatic tired rollers lift should not be
greater than 6 in. Heavy rollers may compact lift
upto 12 in.
70

Production of Rollers
Production (cubic Yard )= 16.3xWxSxLxE/P
Where
W = Width compacted in each pass
S = Compacter speed in mph
L = Compacted lift thickness.
E = Job Efficiency
P = Number of passes required
71

Example
 What is the estimated production rate (CCY per hour) for a
tamping-foot roller with a compaction width of 5 feet? The
following information was obtained from a test strip at the
project:
 Compacted lift thickness = 6 inches
 Average speed = 6 mph
 Number of passes = 5
 Efficiency factor = 0.83
72

Example
 A self-propelled tamping foot compactor will be used to compact a fill
being constructed of clay material. Field tests have shown that the
required density can be achieved with four passes of the roller
operating at an average speed of 3 mph. The compacted lift will have
a thickness of 6 in. The compacting width of this machine is 7 ft. One
bank cubic yard equals 0.83 ccy. The scraper production, estimated
for the project, is 510 bcy/hr. How many rollers will be required to
maintain this production? Assume a 50-min hour efficiency.
16.3 X 7 X 3 X 6 X 50/60
 Compacted cubic yards per hour = ---------------------------- = 428
ccy/hr 4
= 428 / 0.83 = 516 bcy/hr
 No of compactor = 510/516=0.99 One compactor is sufficient
73

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