1. ADIGRAT UNIVERSITY
COLLAGE OF ENGINEERING
AND TECHNOLOGY
DEPARTMENT OF MECHANICAL ENGINEERING
DESIGN OF HOLLOW BLOCK MAKING MACHINE
A Project submitted to the College of Technology, Mechanical Engineering Department in partial
fulfillment of the Requirement for the Degree of Bachelor of Science in MANUFACTURING
TECHNOLOGY ENGINEERING.
BY :
1.FISSEHA WELDEGEBRIAL
2.TEKELE TESFAY
3.TESFAY GEBRELIBANOS
ADVISOR: REDAE HAIMANOT (M.SC)
ADIGRAT, ETHIOPIA 2010 E.C
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1
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The project titled “Design of Hollow Block Making Machine ” by Fisseha
Weldegebrial,Tekele Tesfay and Tesfay Gebrelibanos is approved for the degree of
“Bachelor of science in mechanical engineering”.
Board of Examiners
Name Signature Date
Advisor _______________ _________ _________
Internal Examiner1 ______________ __________ _________
Internal Examiner1 ______________ __________ _________
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ABSTRACT
Hollow block making machine is produce hollow block by accepting and compacting accurately mixture of
cement, sand and water to desired shape, uniform size, weight, and density in the mold while the molding is
vibrating, until the mixture is of the proper volume and consistency. The mold is then withdrawn, and the
finished block leaves the machine.
The Hollow block making machine may works pressing on the principle of Mechanical, Radial,
Hydraulic, Crank press, Centrifugal type etc.It can be operated manually, semi automatic, automatic or
robotic.
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ACKNOWLEDGMENT
First of all we would like to express our heart full gratitude to our advisor and instructor Ato Tariku
Desta(MSc) for his great assistance and comments and his tireless patience encouragement on moral of our
work.We also thanks to AtoAdisuAlemayehu, AtoGetahunAsmare and AtoWorkalemahuManayefor
theirgreat suggestionwhen we designing our projects.
Finally we would like to thank our honest friends for their frequent help throughout our new design
of the mow machine.
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Contents
ABSTRACT ........................................................................................................................................III
ACKNOWLEDGMENT.........................................................................................................................IV
LIST OF FIGURES.................................................................................................................................i
LIST OF TABLE.....................................................................................................................................i
CHAPTER ONE....................................................................................................................................1
1 INTRODUCTION..............................................................................................................................1
1.1 BACKGROUND..................................................................................................................... 1
1.2 PROBLEMSTATMENT .......................................................................................................... 4
1.3 OBJECTIVES......................................................................................................................... 4
1.3.1 GENERAL OBJECTIVE:……………………………………………………………………………………………………….4
1.4 SPECIFIC OBJECTIVES:.......................................................................................................... 4
1.5 BENEFIT AND BENEFICERIES.................................................................................................4
1.5.1 BENEFITS........................................................................................................................................... 4
1.5.2 BENEFITERIES............................................................................................................................ 5
1.6 METHODOLOGY .................................................................................................................. 5
1.7 SCOPE OF SPECIFICATION ....................................................................................................5
CHAPTER TWO...................................................................................................................................6
2 LITRARTURE REVIEW ......................................................................................................................6
CHAPTER THREE ................................................................................................................................9
3 MATERIAL SELECTION .....................................................................................................................9
3.1 IMPORTANT CONSIDERATION IN SELECTING MATERIALS....................................................... 9
3.2 GENERAL CHARACTERISTICS IN MATERIAL SELECTION........................................................... 9
3.3 THE FUNCTIONAL REQUIREMENTS FOR SELECTING MATERIAL............................................. 10
3.4 ERGONOMIC CONSIDERATION FOR THE DESIGN ................................................................. 10
CHAPTER FOUR................................................................................................................................ 12
4 GEOMETRICAL, FORCE AND STRESS ANALYSIS ............................................................................... 12
4.1 GEOMETRIC ANALYSIS....................................................................................................... 12
4.2 FORCE AND STRESSANALYSIS ............................................................................................ 12
4.3 Manufacturing method of the machine .............................................................................. 20
CHAPTER FIVE.................................................................................................................................. 24
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5 COST ANALYSIS............................................................................................................................. 24
5.1 COST ANALYSIS TO MANUFACTURE THE MACHINE.............................................................. 24
5.1.1 Operation process cost................................................................................................................. 24
5.1.2 Raw materials and standard item costs ......................................................................................... 25
5.1.3 Labour costs ................................................................................................................................ 27
5.1.4 Power consumption costs............................................................................................................. 28
5.1.5 Machine depreciation cost ........................................................................................................... 28
5.1.6 Types of production hours............................................................................................................ 29
5.2 Daily Outputs analysis of the Blocks.................................................................................... 31
5.2.1 Unit cost analysis of Hollow Block ................................................................................................. 32
CHAPTER SIX ................................................................................................................................... 33
6 CONCULUSIONS AND RECOMMENDATIONS................................................................................... 33
5.3 CONCLUSIONS................................................................................................................... 33
5.4 RECOMMENDTIONS .......................................................................................................... 34
6 BIBLIOGRAPHY ............................................................................................................................. 35
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LIST OF FIGURES
FIGURE NO.DESCRIPTIONS PAGE NO.
FIGURE1.1 FIRST INVERSIONSOFSINGLESLIDER CRANKCHAIN..................................1
FIGURE 1.2 SINGLE SLIDER CRANKCHAIN................................................................ 1
FIGURE 1.3 FOUR BAR CHAIN / QUADRICCYCLE CHAIN........................................... 2
LIST OF TABLE
Table No. Description Page No.
TABLE 1. OPERATION PROCESSCOSTPER HOURS.................................................. 26
TABLE 2 MACHINE HOUR COSTS...................................................................... 27
TABLE.3 BLANKMATERIAL COST BEFORE MACHINING.......................................... 28
TABLE4 STANDARDITEM COSTS....................................................................... 29
TABLE 5 LABOUR COST PER PERSON.................................................................. 30
TABLE 6 POWER CONSUMPTION COST............................................................... 30
TABLE 7 TOTAL OPERATION TIME...................................................................... 30
TABLE 8 PRODUCTION TIME............................................................................. 31
TABLE 9 BILL OFMATERIALS............................................................................ 3
8. 1
CHAPTER ONE
1 INTRODUCTION
1.1 BACKGROUND
Cement concrete hollow blocks are modern construction materials and as such are used in all the
constructions viz. residential, commercial and industrial building constructions. Construction
industry is a growing a sector. The demand for this product is always high in all cities and other
urban centers due to construction of residential apartments, commercial buildings and industrial
buildings. Growing public awareness of the advantages of the product coupled with increase in
the government and financial institutions support for housing which is a basic human necessity
would ensure a healthy growth in the demand.
Now a days a Cement concrete hollow blocks machine have an important place in modern
building industry. They are cost effective and have a better alternative to burnt clay bricks by
virtue of their good durability, fire resistance, partial resistance to sound, thermal insulation,
small dead load and high speed of construction. Concrete hollow blocks being usually larger in
size than the normal clay building bricks and less mortar is required, minimize construction
time. And provides facility for concealing electrical conduit, water and sewer pipes wherever so
desired and requires less plastering.
THE DESIGN AND MODIFICATION OF THE MACHINE
Mechanisms of the machine
The design 0f this Hollow block making machine based on First Inversions of Single Slider
Crank Chain. This inversion is obtained when link 1(frame) is fixed and links 2(crank) & 4(cross
head) are made the crank & the slider respectively.
Figure 1.1:First Inversions of Single Slider Crank Chain
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Figure 1.2 Single Slider Crank Chain
When one of the turning pairs of a four bar chain is replaced by a sliding pair, it becomes a
single slider crank chain.
It consists of one sliding pair and three turning pairs.
The links 1&2, links 2&3, and links 3&4 form three turning pairs while the links 4&1 form
a slider pair.
Figure 1.3 Four Bar Chain / Quadric Cycle Chain
It consists of four rigid links which are connected in the form of a quadrilateral by four
pin-joints.
A link makes complete revolution is called Crank (4).
The link which is fixed is called fixed link (1).
The link opposite to the fixed link is called Coupler (3).
The fourth link is called Lever or Rocker (2).
It is impossible to have a four bar linkage, if the length of one of the links is greater than
the sum of the other three.
Grashof’s Law: For a four bar mechanism, the sum of the shortest and longest link
lengths should not be greater than the sum of the remaining two link lengths.
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Applies KutzbachGrubler’s Criterion for Plane Mechanisms (only single degree of
freedom/ The no of independent relative motions (movability) (n) =3(l-1)-2j-h i.e. 1=3(l-
1)-2j or 3l-2j-4=0)
Machine:-It is a mechanism which receives energy and transforms it into some useful work.
Machine transmit power & to do some particular type of work.
The parts of a machine move relative to one another
A machine transforms the available energy into some useful work
The links of a machine transmit both power and motion
Mechanism:- one of the links of a kinematic chain is fixed and transmits & modifies a
motion Simple Mechanism (A mechanism with four links.)
Kinematic Chain:the kinematic pairs are coupled in such a way that last link is joined
to the first link to transmit definite motion.
Inversion of Mechanism: the method of obtaining different mechanisms by fixing
different links in a kinematic chain.
Kinematic link/ element: Each part of a machine which moves relative to some other
part.
Kinematic Pair:The two links of a machine when in contact with each other.
Types of links:Flexible Link: It is one which is partly deformed in a manner not to
affect the transmission of motion.
The nature of contact:
Lower Pair:A pair of links having surfaced or area contact between the members.
The nature of mechanical constraint or type of closure:
Closed pair / Self closed pair: the elements of a pair are held together mechanically.
Types of Motions:-Completely constrained motion: the motion between a pair is
limited to a definite direction irrespective of the direction of force applied.
The nature of relative motion:
Sliding Pair: two links have a sliding motion relative to each other.
Turning Pair / Revolving Pair: one link has a revolving motion relative to the other.
Types of joints in a chain:-
Binary Joint: two links are joined at the same connection, J = (3 /2) L - 2.
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1.2 PROBLEM STATMENT
The main problems which we observed from the production area :-
The strength of bonds of the hollow concrete block are weak so on moving by man power
from production area to dry place can be broken.
the complexity of the part of the machine
The machine are stationary for all product
The operation needs a maximum man power to produce one single product.
The production volume is minimized.
Maintenance problem due to joining process.
1.3 OBJECTIVES
1.3.1 GENERAL OBJECTIVE:
The general objective of this project is :
To design hollow block making machine;-
1.4 SPECIFIC OBJECTIVES:
The specificobjectiveof thisprojectis:
To designthe parts/componentsof hollow blockmakingmachine
To model the hollowblockmakingmachineusingappropriatesoftware
To estimate materialcost
1.5 BENEFIT AND BENEFICERIES
1.5.1 BENEFITS
Reducing of high man power to block making
Getting much product within a short time
Enable us to implement 0ur experience ,cumulative of all of all our knowledge and
skill which we acquire in the university
It can integrates all skills /machine shops ,welding shops, pneumatics and hydraulics/
The cost of the over all machine are minimized because some part made from simple
scraps.
To be economical and profitable
It is simple to produce
It is easy to operate manually
can be produce with lower cost
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It can produce Cement concrete hollow blocks within a short time
It saves human energy (labor)
1.5.2 BENEFITERIES
Our country people specially that lives in Tigray.
1.6 METHODOLOGY
We use two types of studying method/s in our new designing. These are:-
1. Observation:- we see videos of this machine from YouTube then we start to Visualization the
mechanism and how it works.
2. Brain storming:- to generate a concept for producing component parts of the machine by
producing a model.
3. Adaptive:- as the machine we manufacture is already exist; we make only minor modification
and change on few parameters such as dimensions, power specifications etc. on the same
technical and conceptual design.
1.7 SCOPE OF SPECIFICATION
The machine which we redesign and modify can be operated manually by human power when
we push the handle for accepting and compacting accurately mixture of cement, sand and water
to desired shape, uniform size, weight, and density in the mold mowing machine. This machine
enables the operator to drive the machine and it is the most comfortable to them.Redesign of the
machine and modification of the existing instruments in appropriate technology to be suitable for
all building industry areas.Further this machine is useful when the land is level and requires an
additional force to move the machine.
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CHAPTER TWO
2 LITRARTURE REVIEW
Walling materials constitute an essential element in housing delivery. It is estimated that it
covers about 22% of the total cost of a building. The choice of walling material is a function of
cost, availability of material, durability, aesthetics and climatic condition. Barry (1996)[1]
defines a wall as a continuous, usually vertical structure of brick, stone, concrete, timber or
metal, thin in proportion to its length and height, which encloses and protects a building or serves
to divide buildings into compartments or rooms.
Hollow block is a walling unit produced from sand, cement and water. It is widely used
as a walling unit. The quality of blocks is a function of the method employed in the production
and the properties of the constituent materials. Hollow blocks are available for the construction
of load bearing and non load bearing structures.
THE PROBLEM ON PRODUCTION IN MACHINE
Concrete blocks have been commonly used in construction for many decades. However, since
the 1980’s several companies have looked for systems, was introduced in order to reduce skilled
labor requirements, permit faster stacking and eliminate wet material. Initially dry stack systems
suffered from quality control. Variation in height dimensions of 1∕16 inch caused deviations
from plumb after just three or four courses and required shims to adjust the height. However,
while still suffering from some height variation, dry stack systems have since improved and are
now competitive in many more market segments than before.
Machines to manufacture concrete blocks provide for a hopper to temporarily hold the
mixed concrete untied concrete until it can be poured in to a mold, Many different cast moldings
are known but generally the negative shape of the finished block is formed on the inside of the
mold. The mold is placed on a support board and then pushed on to a vibrating table where it is
filled with concrete from the hopper. As soon as the mold is filled with concrete, a pressure plate
descends up on the concrete in the mold. Either concurrently with vibrating the vibrating table or
after, pressure is applied to the fresh concrete in the mold by depressing the pressure plate is
raised with the finished pre-cast brick remaining on the support board. The support board and
brick are carried away by aboard carriage for onward transportation by a conveyor system. A
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new support board is then pushed in to the mold, which rests on the vibrator plate. Generally,
such manufacturing systems include a turntable with several work stations as well as the concrete
block molding machine. Such systems are large, relatively expensive and difficult to move.
2MATERIAL USED FOR PRODUCTION OFHOLLOW BLOCKS
All materials used for production of hollow blocks were obtained locally. Sharp sand was used as
fine aggregates and it was made free from deleterious substances by washing. Sieve analysis of
the sand was done to determine its grading.Ordinary Portland cement (Dangote Brand) was used
as the binder. The water used was that which is drinkable and free from impurities and it was
obtained from a tap in the laboratory.
PRODUCTION OF HOLLOW BLOCKS
Cement and sand were measured in different ratio 1:6 to 1:12 by volume batching with the aid of
head pans. The materials were then thoroughly mixed together manually until a homogeneous
mix with uniform color was obtained.
Water was then added in sufficient quantity to ensure workability of the mixture. The
water was judged to be sufficient when a quantity of the mixture pressed between the palms
caked without bringing out water . The composite mixture was then introduced into the mould in
the block moulding machine and the block vibrated for one minute to ensure adequate
compaction as practiced by Raheem (2006) [6]. The green block on wooden pallet was removed
from the block moulding machine and placed on the ground for curing. Water was sprinkled on
the green blocks, at least twice a day for proper curing for twenty eight days.
TESTING OF THE BLOCKS
Compressive strength and density tests were performed on blocks. Compressive strength test was
carried out to determine the load bearing capacity of the blocks. The blocks that have attained the
ripe ages for compressive strength test of 7, 14, 21 and 28 days were taken from the curing or
stacking area to the laboratory, two hours before the test was conducted, to normalize the
temperature and to make the block relatively dry or free from moisture. The weight of each block
was taken before being placed on the compression testing machine in between metal plates. The
block was then crushed and the corresponding failure load recorded. The crushing force was
divided by the sectional area of the block to give the compressive strength. The strength value
was the average of five specimens.
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The density of the block was determined by dividing the weight of the block prior to
crushing, with the net volume. The density value was also the average of five specimens.
Several studies have been carried out on the use of hollow blocks as walling
units.Raheem (2006) [6], considered an assessment of the quality of hollow blocks produced by
LAUTECH Block Industry. The results indicated that compressive strength of 450 x 225 x
225mm (9 inches) blocks increased from 0.54 N/mm2 at age 3 days to 1.68 N/mm2 at age 28
days, while that of 450 x 225 x 150mm (6 inches) blocks increased from 0.53 N/mm2 at age 3
days to 1.59 N/mm2 at age 28 days. Also, about 60% of the compressive strength at 28 days was
developed at day 7 for both 9 and 6 inches blocks.
This study carries out a comparative analysis of hollow blocks by evaluating their
mechanical properties and production cost.
DENSITY OF BLOCKS
The density of 225mm blocks ranges from 2073.5 kg/m3 to 2166.3 kg/m3. Similar trend was
observed for 150mm blocks density ranging from 2041.3 kg/m3 to 2160.9 kg/m3 in [6]. The
values of densities recorded in this study may be attributed to the mix ratio used. Raheem (2006)
used a mix ratio of 1:12.
COMPRESSIVESTRENGTH
These results obtained by Raheem (2006) [6] with values ranging from 1.01 N/mm2 to 1.68
N/mm2 and 0.53 N/mm2 to 1.59 N/mm2 for 225mm and 150mm hollow blocks respectively,
during the same period. The smaller compressive strength recorded in the study are due to the
stronger mix ratio of 1:9 (cement: sand) employed. While only 25 number, 225mm blocks are
produced from one bag of cement in the present study, 33 were produced in [6]. Similarly, 30
numbers, 150mm blocks were produced from a bag of cement in this study as against 42 in [6].
Thus, the reduction in the number of blocks produced per bag of cement resulted in the improved
compressive strength.
From the results of the various tests performed conclusions can be drawn that all the
blocks produced have to satisfy the minimum requirements in terms of compressive strength, by
all available codes.
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CHAPTER THREE
3 MATERIAL SELECTION
The selection of materials for the designing process is a major stage for the process of
translating a new idea in to detailed information from which the product can be manufactured in
any design each of its stages requires decisions about materials from which the product is to be
made and the process for making it. Before making the product, it is very necessary choosing
(selecting) proper materials for the design. But improperly chosen material can lead failure of
the part or component of the designing part and also unnecessary cost. Selecting the best
material for a part involves providing the necessity service performance for the work.
Materials should be chosen from hand books based on the data available on the material is the best
Solution further, it is the method or the way to select the materials interims of their property,
cost, and availability, appease & etc.
3.1 IMPORTANT CONSIDERATION IN SELECTING MATERIALS
Before selecting the materials, it is necessary fulfill the following criteria.
1. Properties of materials
2. Availability and cost
3. Appease, service life and disposal
3.2 GENERAL CHARACTERISTICS IN MATERIAL SELECTION
It is very important studying the characteristics of materials before we select it.
It is advisable selecting materials by their requirements. These are as follows.
1. Toughness
2. Density
3. Wear resistance
4. Corrosion resistance
5. Low cost
6. Yield strength
7. Comprehensive strength
8. Tensile strength
9. Shear strength
10. Machinability
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11. Heat resistivity
3.3 THE FUNCTIONAL REQUIREMENTS FOR SELECTING MATERIAL
Frame part, Base part, Handling part, Crank part, Connecting road, Molding,tamper
Machine should be strong, wear resistance, excellent corrosion resistance and heavy in weight.
The available material is carbon still C-35 because it fulfills the above criteria. Such as
toughness, yield being exposed to wear and corrosion resistance.
For turning part, Sliding part, Fulcrum, Wheel
We consider the following criteria for selection which is
force application
life time
Arrangement
Tensile strength
Shear strength
Machinability
Further we consider other consideration in the selection of those materials like (as a bearing).
The direction of the load relative to their axis
Axial thrust load
Radial load
Combination of axial thrust and radial load
Intensity of loads
Speed of rotation
Stiffness
Class of accuracy of the machine
3.4 ERGONOMIC CONSIDERATION FOR THE DESIGN
Ergonomics describes how human aspects have to be considered by the designer which describes
the following cases like
Ease of use
Comfortable
Positioning of dials and seats
Average weight of human
Average force of humans
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It is very essential and necessary considering the ergonomic consideration for our design. We
determine this consideration by using the height, weight, length, thickness and overall
dimensions of the materials as well as average force and weighs of humans.
In general it deals the human interacting with the product.
These overall ergonomic considerations are here under.
The human held the handle at 115cm from the ground and push dawn 25cm.
The distance of the machine is 90cm from the ground.
The human applied on average force of 250N-275N
The machine is ease to use any person properly
The machine is comfortable to operate it
The total weight of the machine is less rather than the humans so that every person can
operate it easily since the machine is driven by the help of wheel.
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CHAPTER FOUR
4 GEOMETRICAL, FORCE AND STRESSANALYSIS
4.1 GEOMETRIC ANALYSIS
4.2 FORCE AND STRESS ANALYSIS
The main objective is to design a machine for manufacturing of hollow cement blocks. It makes
the product by vibrating and compressing river sand, and other aggregates mixed with cement
and water.
There are numerous factors to be taken into to account when making quality blocks, it is
therefore always important to do trial runs and mixes and have a reputable test the strength of
your blocks on a daily, weekly and monthly basis.
DESCRIPTION HOLLOW BLOCK MAKINGMACHINE
It is sustainable technologies and low cost machine for anywhere in the country.
Local communities can benefit from the machine, unskilled men and women become
active participants in the process.
Gives people an opportunity to empower themselves with new machine.
Cost effective and products can be used by Private Investors, Houses and Entrepreneurs.
Can produce different conventional blocks.
It is easy to set up the machine
It is easy to maintain the machine
MACHINE SAFETY
It is important to give attention to your own safety and the safety of others around you. Please
don’t disregard the vibrating motor. They are applied to the motor for your own safety.
MAINTENANCE
A) At Start of Operation
Before the beginning, perform the following tasks:
Grease tamper trolley, sliding and turning parts
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Check bolts and tighten
B) At End of Operation
After the day’s work, the residual cement/mix should be cleaned from the machine and mold
box. For hardened dirt, a metal scraper and brush can be used. Hitting the tamper to remove dirt
should be avoided as this may damage the legs over time and could affect the quality of the block
made. The machine needs to be cleaned thoroughly. It is strongly recommend that after each
cleaning, the machine is washed down or sprayed with diesel. This prevents concrete from
sticking to the metal and makes cleaning the next day much easier.
C) Periodical
Check handles and pivot pins for wear
Check for visible cracks in the frame/ arms in cases of heavy long-term usage
Check tamper trolley, sliding and turning parts for wear
INPUT MATERIALS FORCEMENT BLOCKS
A) Aggregate
Aggregate is the stone, sand and ash you want to vibrate and compact down and bind together
with the cement. A good aggregate is an aggregate that is free from chemicals, clay and organic
material. A good aggregate will bond well with the cement paste and not react with it.
As a rule of thumb, the denser your finished block the stronger the block will be. You must
choose your aggregates according to your needs.
To achieve a dense block with an aggregate that can be vibrated and compacted down easily you
need to have an aggregate with evenly graded particles ranging from fine dust up to larger stone
of around 9mm. Blending different aggregates/graded materials often produces the best results.
Types of Aggregates
There are a number of types of aggregates that can be used for block making. These aggregates
may need to be blended to suite the quality of the final product.
Never use aggregate that has clay, organic matter or excessive salts in it.
I. SAND
There are different types of sand. Some types are more suitable than others for use in block
making. Some types of sand may need to be blended with other aggregates to get the correct
consistency and suitability.
1, COURSE RIVER SAND
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This sand is usually very good for block making. It should have particle sizes ranging evenly in
proportion from fine dust up to 5mm in size.
Suggestions for use:-
Unblended
Mixed with fine sand
Mixed with ash or slag
Mixed with crusher sand and dust
Some coarse river sands do not have enough fines in them. This could result in the block sagging
and/or breaking. Add crusher sand or dust to help prevent this.
2, RIVER SAND
River sand of medium or fine grade can be used for block making but choose sand that is evenly
graded from fine dust up to 3 or 4mm in size. River sands are not as cohesive as crusher run
sands and natural mined sands.
Suggestions for use:-
Unblended
Mixed with fine sand
Mixed with ash or slag
Mixed with crusher sand and dust
3, CRUSHER RUN SAND
This is usually very good for block making. It tends to be more cohesive than other sands. This
means that the block compacts down well and the freshly made product does not fall apart easily.
Crusher sand is also evenly graded from dust to larger particles. Always check that the crusher
sand does not contain clay. Particle sizes should all be smaller than 5mm.
Suggestions for use:-
Unblended
Mixed with river or natural sands
Mixed with a little stone
4, NATURAL MINED SAND
This sand is mined from quarries and occurs naturally. Slightly coarse evenly graded natural
sand is the best for use with blocks. Natural sand is usually cohesive and makes a strong fresh
product. Make sure the natural sand does not contain clay.
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Suggestions for use:-
Unblended
Mixed with crusher run
Mixed with a little stone
5, FINE SANDS, SEA SAND
These sands are not good for making blocks for the following reasons: they tend to have a high
cement demand; they do not compact well; they do not produce a very cohesive mix; and the
high salt content is corrosive to all metals including.
Suggestions for use:-
Always try and blend this sand with crusher run sand
II. STONE
Stone ranging from 5mm to 9mm can be used to blend in with finer aggregates. Stone used on its
own will not work.
Adding stone will often add strength to your cured product but could make the surface of the
blocks more rough and porous.
III. ASH AND SLAG
Ash and slag by products from power stations, metal works and other industries are often used in
block production. These materials are usually obtainable for very low costs.
It is important to get any ash or slag you use tested for its suitability for use with cement and
other aggregates. Ash or slag may contain high quantities of unsuitable chemicals.
B) Cement
It is recommended 42.5 MPA (or higher) ordinary Portland cement (OPC). If this grade is not
available a higher percent of 32.5 MPA must be used in the product mix.
Cement is your most costly material and by doing trials with different aggregates you will be
able to minimize on cement content and so decrease your costs.
Cement should always be stored in dry place, off the floor and should be used within three
months of the date of manufacture.
Never use cement that has lumps in it and only use cement from a well-known, quality brand.
Cement sets when mixed with water by way of a complex series of hydration chemical reactions.
The different constituents slowly hydrate and crystallise while the interlocking of their crystals
gives the cement its strength after the initial setting. Immersion in warm water will speed up the
23. 16
setting. The time it takes for cement to set varies; and can take anywhere from twenty minutes
for initial set to twenty four hours, or more, for final set.
C) Water
Only clean, clear potable water should be used in the manufacture of the blocks.
Any organic material in water will prevent the cement from setting. Chemicals and impurities
could also affect the strength of the end product.
Never use, salty or brak water (contaminated water). It is advisable to get your water tested for
impurities.
BLOCK MAKINGPROCESS
A) Organizing Your Site
These are the things that you must think about in order to turn your site into an efficient Block
yard.
Access: Trucks must be able to deliver your materials easily and take away your blocks.
This must not get in the way of the people making your products.
Storage for materials: The sand and stone must be stored close to where you mix the
concrete and in piles separated by a wall or partition. Make sure that rain water drains away
easily. You must take even greater care of your cement stock because it will go hard and be
unusable if it gets wet. Do not stack the pockets straight on the ground because they will
absorb moisture from the soil. Protect the pockets from rain.
Cement StorageCement can be supplied in 50kg bags or in bulk. For large daily production
- cement stored in a cement silo is recommended. Bags of cement should be stored under
cover off the floor and away from any damp conditions. Packing the bags close together also
prevents any moist air circulation around the bags. Always store the cement bags so that
they are used on a first in first out basis. This will ensure that the oldest cement is used first.
Aggregate StorageThe stockpile of aggregate should be protected from rain by storing it
under a roof or covering it with plastic. Do not let the aggregate get contaminated with
ground soil or any organic matter such as leaves from a tree. Position your aggregate close
to your mixing plant.
Production area:Your day’s production of blocks cannot be moved for at least a day.
Therefore the ideal size of the slab must be large enough for two days production.
24. 17
Product:The Blocks that you have made should be stacked reasonably close to the
production area and in a place that is good for loading trucks.
The block density is a good indicator of weight. By weighing the block, you will be able to
ascertain its density. Always be aware of breakages to the corners and edges of your
product. Strength can be tested by knocking two blocks together after curing and being dried
out. A ringing sound indicates good strength while a hollow sound means that the blocks are
weak.
B) Mixing Process
Place half of your aggregate into the pan mixer then add the cement followed by the remaining
aggregate. Allow the cement and aggregate to mix dry until a consistent even colour is produced.
Then start adding in water until the correct moisture content is reached.
Batch mixing – Volume batching
For high quality blocks a pan mixer must be used. Always run a series of trials with different mix
proportions. By evaluating your results you can adapt your mix to be more cost effective.
Start you trial mixes with 1 part cement to 6 parts aggregate. This translates to one bag of cement
to 3 level wheelbarrows of aggregate. Test your block strengths at 28 days.
The strength of concrete depends on the relevant proportion of water and cement.
Therefore the higher content of water the weaker the concrete. Water used per 50kg of cement
should be 0.4 x50kg or 20 litres. The mixes used for block making are semi dry, the water acts as
a lubricant and helps with the compaction of the product via pressure or vibration.
Test your mixes by:
Make a ball of concrete in your hand
If the mix is too dry the ball cannot be formed and will crumble
If too wet it loses its shape and moisture sticks to your hand
If the content is about right, a ball will be formed and slight water sheen can be seen on the
surface of the concrete mix.Try and measure the water content added so that you can establish
the correct amount needed per mix. This will still vary due to the water content in the aggregate
being used.
Water Content
The moisture content within the mix is crucial. It is important for the following reasons:-
25. 18
The correct water content allows for good dense compaction by lubricating the aggregate.
Too much water will lubricate the aggregate to such an extent that the block will fall
apart or sag when removed from the mould.
With the correct water content the block will release easily from the mould. No suction
between the mould and block will be created.
Do not allow your mixed batch to stand for more than half an hour. This will prevent strength
loss in your cement and the lubricating water will not dry off. Your mix and aggregate may need
to be adjusted to get a quality looking block
C) Getting Started - Concrete Slab
A concrete slab on which you will make and cure your blocks is advisable. Your slab size is
dependent on the daily production of machine. Put a very gradual slope on your slab to allow for
sufficient run off of water.
A concrete slab gives you the following advantages:-
Less block breakages
Less contamination of aggregate
A better surface to cure on
Easier to move blocks/bricks
Easy to move the machine
D) Product Making
Ensure all slide rods are greased at all times.
Move the tampers in and out of the mould box and ensure it moves freely
Using the rake, push the mix into the mould box ensuring it is completely filled.
Level the mix off on the mould box. Press the vibration button to pre-vibrate and then fill
the mould box again and level off.
Remove any excess mix from the mould box.
Align holes in the carrier frame and Push tamper into mould box.
Press vibration button for a few seconds until the height stops reaches the required
product height.
Pull down on handle, lifting tamper and mould box together
E) Curing Of Blocks
26. 19
Curing is one of the most essential parts of block production. Correct curing has a big effect on
the quality of the end product and also the cost of the end product. Often with good curing the
cement content of your blocks can be reduced drastically.
It is recommended that the freshly made blocks are covered immediately with a 250micron black
plastic and cured by keeping the plastic over the blocks for a minimum of 7 days. Remove the
curing plastic briefly to thoroughly wet the blocks twice a day starting from the day after
production.
A record should be kept with the curing block of when they were produced so the curing plastic
can be removed on the morning of the eighth day after production.
With 7 days curing the blocks will have reached approximately 75% of their final strength.
Blocks are usually sold after 7 days curing whereas pavers should be cured for a minimum of 14
days.
TROUBLE SHOOTING
A) Machine Related
Insufficient Vibration
Check the vibration rubbers as these could need replacing. Also check that the mould box is
sitting flush on the ground and is locked in place.
B) Product Related
Product Heights not achieved.
Insufficient vibration could also cause desired product height not to be achieved.
Different materials may require different water contents / mix designs / vibration duration to
achieve desired product height.
Crumbles or breaks
This shows the product has low strength. Adjust your mix and make sure you have the correct
amount of water, cement and aggregate ratios.
Corners break
This shows that there is little compaction check mix and adjust machine accordingly. Also check
for cement build up in the corners of the mould box.
Porous surface
The product has too many large particles. Adjust your mix accordingly and add a bit more fine
particles.
27. 20
Dense surface
The product has too many small particles. Adjust your mix accordingly.
Too many fines can also cause product height to be too high.
C) Other Factors to be considered
Soils, cements, mix preparations, material codes, building materials, building codes, local
regulations, external conditions etc. are all important considerations to take into account to
produce quality product and achieve acceptable building standards.
4.3 Manufacturing method of the machine
It includes:-
Preparation of project
Prepare the drawing
Preparation of the materials
Selection of tools
Selection of machine
Part products are prepared
Assembling of parts
Final hbm is produced
Manufacturing method of machine prepare working drawing than transfer the working drawing
with the help of lay outing marking on the work.
Production includes preparation of the Manufacturing method machine. Some important
procedures and processes that may be used to manufacture of the product included as
recommendations beside a material specification to ease preparation.
Cutting
Cutting operation is required in most of the production that incorporate sheet metal processing
and may include use of simple hand tools while further shaping of components is done through
cutting tools. The raw material has to be cut to size. This is done with a variety of cutting tools;
28. 21
Special power hack saws designed for cutting metal have hardened blades and a feed mechanism
for even cutting.
The sawing processes is used because it has advantages, including doing the job faster, saving
material, and using less power. Also, a minimum of material is lost as chips.
Fabrication
Fabrication, when used as an industrial term, applies to the building of machines and structures
by cutting, shaping and assembling components made from raw materials. Metal fabrication is a
value added process that involves the construction of machines and structures from various raw
materials usually based on the engineering drawings.
Welding
Welding is the process of joining two pieces of metal by fusing them together to produce
essentially a single piece of the metal. Its products are known as “weldments” The formed and
machined parts will be assembled and tack welded into place then re-checked for accuracy. So
we used for manufacturing of machine the AC welding process. A fixture used to locate parts for
weldments.Then we completes welding per drawings. The types of welding used in these
manufacturing processes are3 but joint, lap-joint, T-joint, two kinds of corner joints, two kinds of
edge joints.
The joining process in the production is thus recommended to use welding due to its availability.
The selected process arc welding has advantages of high production rate, minimum distortion
and low annealing of base metal in addition to the avoidance of the disadvantages like high cost
requirement with higher heat input and limitation on material thickness that of oxy-fuel gas
welding and requirement of expensive equipment and poor strength of resistance welding.
Drilling
It is one of the cutting operations using drill bits to produce rough holes. The machine tool
involved in this case is a drill press. There are two cutting edges that produce chips similar to
those produced in turning on a lathe and a certain web region that extrudes the metal at the center
of the hole which is not removed by the cutting edges. Both lips (cutting edges) of a drill operate
with variable rake angle, inclination angle, and clearance angle along the cutting edge. The flutes
of a drill play the important role of conveying the chips out of the hole and the helix angle of the
drill is important in this connection.
Limits, Fits and Tolerances
29. 22
The maximum and minimum limitations for a given feature are known as the limits. To ensure
that an assembly will function correctly, its component parts must fit together in a predictable
manner. Now, in practice, no component can be manufactured to an exact size, and one of the
problems facing the designer is to decide the upper and lower limits of a size which are
acceptable for each of the dimensions used to define shape and form and which will ensure
satisfactory operation in service. The algebraic difference between the upper and lower limit of
size is known as the tolerance. The tolerance the amount of variation permitted.
Process involved at construction of machines from various materials based on drawings
Base
Three piece of square bar (850x25x25) welded to gather at perpendicular to each other.
Frame
Two piece of square bar (850x25x25) drill two holes of 9mm at the end and welded to the base at
the center and perpendicular to the base.
Molding box
By cutting three piece of 3mm sheet metal (300x250) then by using rolling machine and welding
to produce three cylinders of 90mm and joined together by using flat iron (390x25x3)
Cut 3mm sheet metal (1200x250) and using bending machine bend to square box of (400x200)
then weld the end edge. Weld angle iron to all corners and to bottom edge to add strength to the
mold box. Weld sheet metal all to the top of the mold box for entering the mixture freely.
Round pipe (20x60) welded to the connecting plate instead to round bar (18x67) which is
welded between square pipe (30x30x120) and flat iron (160x35x3) that welded them to the mold
box
Tamper
Cut sheet metal (390x190x3), by using chisel cut tree holes of 91mm that fit to mould cylinder
then weld four piece of angle (25x25x200) as a frame on it and weld two pieces angle iron
(25x25x360) that used as limit for compacting the block.
Arm
Two piece of angle iron (810x25x3) that used as crank welded to round pipe ( 25x720) that
used as a handle then weld to round pipe( 25x540) that used as turning part at a fulcrum.
Clamp
30. 23
Cut flat iron to 100mm and make arc of 25mm, cut flat iron to 25mm arc cord and weld to
each other then drill two holes of 9mm at the end.
Assembly
1. Insert the reciprocating part on moulding box into the frame
2. Insert the round bar ( 20x600) that used as a fulcrum into to round pipe( 25x540) that
used as turning part
3. Clamp the round bar ( 20x600) that used as a fulcrum to the frame
4. Clamp connecting plate with the crank
5. Inset the tamper into the mould box.
31. 24
CHAPTER FIVE
5 COST ANALYSIS
5.1 COST ANALYSIS TO MANUFACTURE THE MACHINE
The main aims of cost analysis are used to know overall cost of the machine this includes:-
Operation process cost
Raw material and standard item cost
Labor cost
Power consumption and consumable material costs
Machine depreciation costs
5.1.1 Operationprocesscost
The Operation process cost includes all machine cost used to produce each parts./machine shop,
welding machine,grinders,column drills,etc,
Table 1. Operation process cost per hours
No Types of machine
Cost per hour
Eth.birr
Birr Cents
1 Power hack saw 15 00
2 Welding machine 10 00
3 Column drilling machine 15 00
4 Lathe machine 30 00
5 Milling machine 40 00
32. 25
Table 2.Machine hour costs
No Types of machine Total machine
hours
Total costs
Eth.birr
Birr Cents
1 Power hack saw 30min 7 50
2 Welding machine 1hrs 10 00
3 Column drilling machine 20min 5 00
4 Lathe machine 15min 7 50
5 Milling machine 20min 13 35
Total costs 42 35
5.1.2 Raw materialsandstandarditem costs
The material cost refers to those raw materials which are consumed to produce components of
the hollow concrete block machine.
This analysis of cost estimation of consumed material is carried out on the base of the
data obtained from
Local markets
Purchase of the university
Our experience
33. 26
Blank material costs
Table.3.Blank Material cost before machining
No Materials Unit Qty Size
Unit costs
Eth.birr
Total costs
Eth.birr
Birr Cents Birr Cents
1 Round bar Pcs 01 20 x1000mm 200 00 200 00
2 Solid bar Pcs 01 25x25x5000mm 291 00 291 00
3 RHS Pcs 02 30x30x500mm 26 00 52 00
4 Angle iron Pcs 02 25x25x1000mm 103 00 206 00
5 Flat iron Pcs 02 4x40x800mm 29 00 58 00
6 Sheet metal Pcs 01 2.5x30x1500m
m
200 00
200
00
7 Round pipe Pcs 01 30x500mm 22 00 22 00
8 Angle iron pcs 01 20x20x1600mm 75 00 75 00
Total costs 1104 00
Standard item costs
This are a cost that is directly purchased from the markets and doesn’t any operation to make an
item./finished product/
34. 27
Table4.Standard item costs
No Materials Unit Qty Size
Unit costs
Eth.birr
Total costs
Eth.birr
Birr Cents Birr Cents
1 Bolt pcs 06 M8 3 00 18 00
2 Nut pcs 06 M8 3 00 18 00
3 Grinding disk pcs 02 180mm 25 00 50 00
4 Cutting disk pcs 01 180 mm 20 00 20 00
5 Pin cylindrical pcs 00 00
6 Electrode E6013 pkt 1/8 2.5mm 150 00 18 50
7 Power hack saw blade pcs 02 60 00 120 00
8 Thinner liter 1/4 52 00 13 00
9 Anti rust pcs 1/8 Gallon 220 00 27 50
10 Paint pcs 1/8 Gallon 220 00 27 50
11 Brush pcs 03 3.5” 5 00 15 00
12 Motor pcs 01 Single phase
,0.9kw 2500 00 2500
00
13 Wheel pcs 04 1 45 00 180 00
14 Hack saw blade made
of Sweden pcs 05 T-24 22 00 110 00
Total costs 3117 00
5.1.3 Labourcosts
The labour cost is the cost that is paid to a person to produce the real parts of the projects and it
includes:-
Measuring and lay out costs
Machine operation costs
Assembly costs
Miscellaneous costs
35. 28
Table 5.Labour cost per person
No Materials
Unit costs per hours
Eth.birr
Birr Cents
1 Operation cost per hour for the person 30 00
5.1.4 Powerconsumptioncosts
The power consumption cost is the cost of power used during the production of the product
Table 6. Power consumption cost
No Materials Power
consumption
cost per kw
Total hour
used
Total cost
Eth. Birr
Birr cents
1 power consumption cost per
hour
1.5birr 5hrs 7 50
5.1.5 Machinedepreciationcost
In our case machine depreciation costs is 20_birr
5.1.7 Total costs of the operation to produce the hollow concrete block machine
Table 7. Total operation time
No operation Total hours
1 Total production time 12.5
36. 29
5.1.6 Typesofproductionhours
Table 8. Production time
No Types of work Total hours
1 Bench work 3
2 Machining 1
3 Assembling 5
4 Miscellaneous 1.5
5 Layout 2
Total hours 12.5
Labour costs = 12.5 x 30birr
=375birr
Partial grand Total labor cost of the machine
= Power consumption cost +Labour costs + Standard item costs + Blank material costs +
Operation process cost = 7.5 + 375 + 3117 + 1104 + 42.35
= 4645.85birr
Contingency 10%
= Partial grand Total labor cost of the machine x 10%
= 4645.85 x 0.01
= 46.45birr
Total cost of the machine
= Partial grand Total labor cost of the machine + Contingency 10%
= 4645.85 + 42.45
= 4588.30
38. 31
5.2 Daily Outputs analysis of the Blocks
A)Based on machine performance
Let
Filling the mix into the mold and compressing take two to three minute,
Eight working hour per a day
Therefore the machine can produce 160 to 240 pieces per a day (based on operator).
B) Based on volume of Sand and Cement
Note: 1 wheelbarrow = 65 litres
Bag cement = 33 litres
Blocks: 20% additional vibration compaction
(All values are theoretical and approximate and should be verified with trials)
Mixes are subject to change if using higher MPA cements or with variations in types of materials
i.e. aggregates used.
Hollow Block 8” (390 x 190 x 190)
Volume = (LHW)-3(𝜋𝑟2
l)
Volume = (390x190x190)-(3xπx190x4.52
) =11.23 litters
Volume + 20% compaction = 13.46 litters
Mix 1 to 8
4 wheelbarrows aggregate (260 litres)
1 x 50kg bag cement (33 litres)
Total: 293 litres
Blocks produced = 22
Therefore for one day production up to 30 wheelbarrows aggregate and 7 bag cements are
required.
Mix 1 to 10
5 wheelbarrows aggregate (330 litres)
1 x 50kg bag cement (33 litres)
Total: 363 litres
Blocks produced = 27
Therefore for one day production up to 30 wheelbarrows aggregate and 7 bag cements are
required.
39. 32
5.2.1 Unit cost analysisofHollowBlock
1 wheelbarrows aggregate = 30 birr
1 bag of cement =90 birr
Total = 120 birr
Mix 1 to 8(22 block produced)
4 wheelbarrows aggregate =100birr
1 x 50kg bag cement =90birr
Total cost of material = 190 birr
Assume 10% for labor =1.9birr
Assume also 20% for machine and others =3.8birr
Total = 195.7 birr
Total cost incurred in producing one unit of Hollow Block 8”(390x190x190)
=(195.7/22)
=8.90birr
Mix 1 to 10(22 block produced)
5 wheelbarrows aggregate =125birr
1 x 50kg bag cement =90birr
Total cost of material = 215 birr
Assume 10% for labor =2.15birr
Assume also 20% for machine and others =4.3birr
Total = 221.45 birr
Total cost incurred in producing one unit of Hollow Block 8” (390x190 x190)
=(221.45/27)
=8.20birr
The unit cost of Mix 1 to 10 and Mix 1 to 8 hollow blocks are 8.2 birr and 8.9 birr respectively,
This due to reduction of aggregate in quantity per bag of cement and responsible for the increase
in cost. This is however compensated for by the improvement in quality as the higher
compressive strength.
40. 33
CHAPTER SIX
6 CONCULUSIONS AND RECOMMENDATIONS
5.3 CONCLUSIONS
The functional requirement from the hollow concrete blocks is that:-
To get strongly bonded concretehollow block
To reduce the applied load due to vibration
To reduce man power because it can be operated by one person only from input to out put
production
Moving from one station to the next station
Then to get the above output or advantage before the start of production the operator must
check the load vibration working or not, check the holes are clean and pure if nothe must clean
this cleaning process must be continuous because of getting the needed surface finish in every
hollow concrete block production .
Finally after finishing the daily scheduled production the operator first switch of the
motor and unplug the socket from socket outlet and secondly clean by water all surface of the
machine to make ready for the next day production.
N.B.:- Do not wash the motor by water, the inside coils may make short and the load vibratory
machine stops to function.
41. 34
5.4 RECOMMENDTIONS
The hollow block machines are used to produce the hollow concrete block to the planned mix
ratio of cement, sand and aggregates. The local market hollow block machine are not strongly
bonded due to the compaction force of the operator because of this some of the body parts of the
block un bonded this causes the block to break at transportation from the production are to
curing area.
Our machine can be easily manufactured from available materials, scraps and motor /load
vibrator/ and wheel only and also can be manufactured with minimum cost and the machine are
movable from one production station to the next this helps to reduce the transportation cost of the
block and it become safe of break and cure at that station.
The block also strong because of the applied force of the operator and the vibrate force of
the motor.
Finally ours machine can produce only one /single block atevery operation time and also
if we increase the number of box to produce two or more blocks at a time and to increase the
number of box the designer must increase the output power of the load vibrator motors.
At the end this paper is open for the next research and who want to improve this vibrator
hollow block machine.
42. 35
6 BIBLIOGRAPHY
[1] Concrete block machine video BLOX-1S - YouTube_2
[2] US Patent, DonalP.ChennelssConcrete Block press Feb/17/2005
[3] J.P. Kaushish, BhagwanDass, O.K. Gautam&Mahindra Pal Published by : Central Building
Research Institute, Roorkee (U.P.) INDIA December 1990 Reprinted June 1994
[4] International Journal of Sustainable Construction Engineering & Technology (ISSN: 2180-
3242)Vol 3, Issue 1, 2012
[5] Barry, R., (1996),”The Construction of Buildings”, 7th edition, Vol 1, England, Blackwell
Science.
[6] Hodge, J.C. (1971), “Brick work”, 3rd edition, England, Edward Arnold.
[7] Mahalinga-Iyer, U. and Williams, D.J. (1997), “Properties and Performance of Lateritic Soil
in
Road Pavements”, Engineering Geology, Vol 46, pages 71 – 80.
[8] Oladeji O. S. and Raheem A. A. (2002), “Soil Tests for Road Construction”, Journal of
Science, Engineering and Technology, (JSET), Vol 9 (2), pages 3971-3981.
