jspl report
TRANSCRIPT
0
15th may-5 July ’14
KUNAL KUMAR
MANOJ CHAUDHARY
Civil Engineers (2nd year)
INDIAN INSTITUTE OF TECHNOLOGY
ROORKEE
Report on Training at JSPL,Raigarh
1
CERTIFICATE
This is to certify that this project report entitled “REPORT ON SUMMER
TRAINING AT JSPL, RAIGARH” submitted to CIVIL DEPARTMENT, JINDAL
STEELS AND POWER LTD. is a bonafide record of work done by KUNAL KUMAR
and MANOJ CHAUDHARY under my supervision from 15th may to 5th july
2014.
NAME OF STUDENTS INSTITUTE ENROLL. NO.
………………………………. 12113055
KUNAL KUMAR
12113059
……………………………….
MANOJ CHAUDHARY
………………………………………
AJAY KUMAR AGARWAL
HOD,CIVIL DEPTT.
JSPL,RAIGARH
(CHATTISGARH)
2
ACKNOWLEDGEMENT
We take this opportunity to express our profound gratitude and deep regards
to our department head Ajay Kumar Agrawal (Sr. D.G.M. & HOD Civil
Department) for his exemplary guidance, monitoring and constant
encouragement throughout our training period. The blessing, help and
guidance given by him time to time shall carry us a long way in the journey of
life on which we are about to embark.
We also take this opportunity to express a deep sense of gratitude to our
mentors Mr. Sandeep Kumar Sahoo, Mr. Dibyagan Das, Mr. P K Singh & Mr.
Arun Kumar Arya for their cordial support, valuable information and guidance,
which helped us in completing this task through various stages.
We are obliged to staff members of JSPL, Raigarh, for the valuable information
provided by them in their respective fields. We are grateful for their
cooperation during the period of our assignment.
Lastly, we thank Almighty, our parents, and our esteemed professors of our
college for their constant encouragement without which this training would
not be possible.
KUNAL KUMAR &
MANOJ CHAUDHARY
3
ABSTRACT
This report is pertaining our 50 day summer training at JINDAL STEELS AND
POWER LTD. Plant at raigarh, chattisgarh.
Our internship duration can be segmented broadly into four sites as in:
1)-CORPORATE TOWER PROJECT-Here we were exposed to rigorous
dimensions of civil engineering. We witnessed the use of different techniques
usually employed in civil engineering, measured beam sheer deflections,
understood the philosophy of green and energy efficiency concepts of
construction.
2)-Speedfloor at Parsada –Here we learnt and understood concepts of
speed flooring, a new and rather revolutionary way of construction. Also use of
foam concrete was demonstrated.
3)-Ash Dyke site-Here, we learnt the risks and hazard management
involved in dykes, which stretched upto 5,00,000 lakh sq. m in area. The safety
issues involved in such dykes and difference between dykes and dams was
understood here.
4)-Blast furnace and Stock home site-Here the tips and tricks
involved in backfilling and the need of retaining walls was demonstrated and
understood.
We believe this internship has not only increased our knowledge of civil
engineering but will pay pivotal role in honing our skills as civil engineers.
4
LIST OF CONTENTS
page no.
Certification………………………………………….1
Acknowledgement…………………………………..2
Abstract…………………………….........................3
List of contents………………………………………4
About JSPL…………………………………………..6
CHAPTER 1-CORPORATE TOWER PROJECT
1.1 Project description……………………………….8
1.2 salient features…………………………………. 9
1.3 Philosophy behind ……………………………..11
1.4 General sequence
of civil engineering………………………………14
1.5 Photo gallery……………………………………..30
1.6 Conclusion………………………………………..32
CHAPTER 2-Speed flooring
2.1 Introduction……………………………………...33
2.2 Advantages…..................................................36
2.3 How it works………………………....................38
2.4 Design…………………………………………….41
2.5 Price comparison………………………………..43
5
2.6 Specifications…………………………………….50
2.7 Project samples………………………………….52
2.8 Conclusion………………………………………..56
CHAPTER 3-ASH DYKE VISIT
3.1 Introduction………………………………………57
3.2 Construction……………………………………..58
3.3 Layout…………………………………………….60
3.4 Failures of Dykes………………………………..62
3.5 How do they fit…………………………………..65
3.6 Raising methodology……………………………67
3.7 Conclusion……………………………………….71
CHAPTER 4- INDUSTRIAL TOUR &
OTHER SITE’s VISIT
4(i)Back filling of stock home………………………72
4(ii)Blast furnace site……………………………….75
4(ii).1 Design philosophy……………………………76
4(ii).2 Diagram of B.F……………………………….78
4(II).3 Conclusion…………………………………….80
6
With its timeless business philosophy JSPL is primed to not merely survive but
win in a marketplace marked by frenetic change. Indeed, the company’s
scorching success story has been scripted essentially by its resolve to innovate,
set new standards, enhance capabilities, enrich lives and to ensure that it stays
true to its haloed value system. Not surprisingly, the company is very much a
future corporation, poised to become the most preferred steel manufacturer
in the country.
An Overview of
jspl products
RAIL PARELLEL FLANGE BEAMS
PLATES &COILS
ANGLES & CHANNELS
PANTHER TMT REBARS
WIRE RODS FABRICATED SECTIONS
JINDAL SPPEDFLOOR
SEMI FINISHED GOODS
POWER MINERALS SPONGE IRON
About JSPL
7
PRODUCTS
JSPL is an industrial powerhouse with a dominant presence in steel, power, mining and infrastructure sectors. Part of the US $ 18 billion OP Jindal Group this young, agile and responsive company is constantly expanding its capabilities to fuel its fairy tale journey that has seen it grow to a US $ 3.6 billion business conglomerate. The company has committed investments exceeding US $ 30 billion in the future and has several business initiatives running simultaneously across continents.
Led by Mr Naveen Jindal, the youngest son of the legendary Shri O.P. Jindal, the company produces economical and efficient steel and power through backward and forward integration.
From the widest flat products to a whole range of long products, JSPL today sports a product portfolio that caters to markets across the steel value chain. The company produces the world's longest (121-meter) rails and it is the first in the country to manufacture large-size parallel flange beams.
JSPL operates the largest coal-based sponge iron plant in the world and has an installed capacity of 3 MTPA (million tonnes per annum) of steel at Raigarh in Chhattisgarh. Also, it has set up a 0.6 MTPA wire rod mill and a 1 MTPA capacity bar mill at Patratu, Jharkhand, a medium and light structural mill at Raigarh, Chhattisgarh and a 2.5 MTPA steel melting shop and a plate mill to produce up to 5.00-meter-wide plates at Angul, Odisha.
An enterprising spirit and the ability to discern future trends have been the driving force behind the company's remarkable growth story. The organisation is wedded to ideals like innovation and technological leadership and is backed by a highly driven and dedicated workforce of 15000 people.
JSPL has been rated as the second highest value creator in the world by the Boston Consulting Group, the 11th fastest growing company in India by Business World and has figured in the Forbes Asia list of Fab 50 companies. It has also been named among the Best Blue Chip companies and rated as the Highest Wealth Creator by the Dalal Street Journal. Dun & Bradstreet has ranked it 4th in its list of companies that generated the highest total income in the iron and steel sector.
8
CHAPTER-1
1.1 project description-
AREA CALCULATION AREA in sq. m
Total plot area 45230
Actual FAR 0.19
ACTUAL GROUND COVERAGE 8687
Build up Summary
floor basement Ground floor
First floor
Second floor
Third floor
Fourth floor
Fifth floor
Sixth floor
Terr-ce
total
Sq.ft 93469 61361 30372 21703 10282 10529 10592 7538 1367 247150
parking facility
Basement 195(4w) + 45(2w)
Open parking 200
Total 440
common facilities
Capacity of conf. hall &presentation room at G. floor
63+56=119
Capacity of cafeteria 204
Capacity of M. purpose hall at F. floor 168 Capacity of auditorium at fifth floor 119
CORPORATE TOWER PROJECT
9
1.2
Objective-to have a centralised office for all commercial deptts. At
one place,to avoid/to restrict entry of outside people into main plant
area
Departments to be located in new Corporate tower-(total cap. For
680 nos. seating)
(1)Procurement deptt. (2)Finance &Accounts (3)Audit,Excise,Sales
tax &materials (4) Marketting deptt. (5) HR deptt. (6) CSR,PR
&Liasioning,legal deptt. (7) P&A (8) IT,Admin & security (9)Costing
&Commercial deptt. (10) Offices for visiting officers from other
locations (11) Office of Executives director-in-charge (12) Offices of
Hon. MD.,Hon. DMD (13) Offices for other visiting VIP’s (14) Office of
Hon. Chairman
Main key feautres of building- -Total Built up area :- 2,47,150SFT (Basement 93469 SFT + Super
structure 153681)
-SPECIFICATIONS AS PER THE REQUIREMENTS OF PLATINUM
RATING LEED CERTIFICATION FOR GREEN BUILDING.
-Basement in RCC frame structure having provision of 195 four
wheelers & 45 nos Two wheelers parking and Super strucure is
composite strucure in 5 different crores (towers) up to G+6 Floors.
-Exterior façade is having structural Glazing with double glass (8mm
Glass+ 16mm air gap +8mm Glass) of SCHUCO SYSTEM and Stone
cladding on wall surface.
SALIENT FEATURES
10
-Total Estimated cost excluding Loose furniture:- Rs. 78.60 Crores.
-Target Date of completion of project: 30-09-2013
-Main Contractors:- 1.M/s.JMC Projects(Structural work),
2.M/s.GDCL(Civil Masonary & finishing including interiors)
3.M/s. Sterling & Wilson (All MEP work i.e Electrical, HVAC,BMS,Fire
detection & Fire Fighting, Plumbing & Sanitary)
4. M/s Glaze Techno Ind.(structural Glazing)
11
1.3
one of the salient features of the corporate towers have been
its philosophy of being energy efficient and setting an
example of how to respect nature and how to conserve the
constantly depleting power resources.
The building has SPECIFICATIONS AS PER THE REQUIREMENTS OF
PLATINUM RATING LEED CERTIFICATION FOR GREEN BUILDING.
this is both a matter of pride and honour for its architects and
engineers.
GO GREEN!!
PHILOSOPHY BEHIND BUILDING
12
-) Thermal insulation of roofs using expanded polystyrene -)Thermal insulation on exterior walls -)Extensive use of double glass units (DGU) in structure glazing -)Illumination control movement sensors -)Stone cladding that creates a air space to keep the structure cool -)Sensor based heat and ventilation system -)Sensor based A/C controls or HVAC controls -)use of Belgium carpets, the carpets used are made of recycled materials thus a step towards aiding the constantly deteriorating natural resources All these special features have been successfully incorporated in this mega structure to make an energy efficient building. These small measures are a step forward in decreasing nature’s burden.
FEATURES THAT MAKE CORPORATE BUILDIND GREEN
13
We do not inherit the earth from our ancestors, we borrow it from our children.
14
1.4
SEQUENCE OF STRUCTURE WORK
1) Site Clearance
2) Demarcation of Site
3) Positioning of Central coordinate ie (0,0,0) as per grid plan
4) Surveying and layout
5) Excavation
6) Laying of PCC
7) Bar Binding and placement of foundation steel
8 ) Shuttering and Scaffolding
9) Concreting
10) Electrical and Plumbing
11) Deshuttering
12) Brickwork
13) Doors and windows frames along with lintels
14) Wiring for electrical purposes
15) Plastering
16) Flooring and tiling work
17) Painting
18) Final Completion and handing over the project
CONSTRUCTION PROCESS AND MATERIALS USED
Site Clearance- The very first step is site clearance which involves removal of
grass and vegetation along with any other objections which might be there in
the site location.
Demarcation of Site- The whole area on which construction is to be done is
marked so as to identify the construction zone. In our project, a plot of
450*350 sq ft was chosen and the respective marking was done.
Positioning of Central coordinate and layout- The centre point was marked
with the help of a thread and plumb bob as per the grid drawing. With respect
to this center point, all the other points of columns were to be decided so its
exact position is very critical.
Excavation
Excavation was carried out both manually as well as mechanically. Normally 1-
2 earth excavators (JCB’s) were used for excavating the soil. Adequate
precautions are taken to see that the excavation operations do not damage the
adjoining structures. Excavation is carried out providing adequate side slopes
General sequence of civil engineering
15
and dressing of excavation bottom. The soil present beneath the surface was
too clayey so it was dumped and was not used for back filling. The filling is
done in layer not exceeding 20 cm layer and than its compacted. Depth of
excavation was 5’4” from Ground Level.
PCC – Plain Cement Concrete
After the process of excavation, laying of plain cement concrete that is PCC is
done. A layer of 4 inches was made in such a manner that it was not mixed
with the soil. It provides a solid bas for the raft foundation and a mix of 1:5:10
that is, 1 part of cement to 5 parts of fine aggregates and 10 parts of coarse
aggregates by volume were used in it. Plain concrete is vibrated to achieve full
compaction. Concrete placed below ground should be protected from falling
earth during and after placing. Concrete placed in ground containing
deleterious substances should be kept free from contact with such a ground
and with water draining there from during placing and for a period of seven
days. When joint in a layer of concrete are unavoidable, and end is sloped at an
angle of 30 and junctions of different layers break joint in laying upper layer of
concrete. The lower surface is made rough and clean watered before upper
layer is laid.
16
LAYING OF FOUNDATION
At our site, Raft foundations are used to spread the load from a structure over
a large area, normally the entire area of the structure. Normally raft
foundation is used when large load is to be distributed and it is not possible to
provide individual footings due to space constraints that is they would overlap
on each other. Raft foundations have the advantage of reducing differential
settlements as the concrete slab resists differential movements between
loading positions. They are often needed on soft or loose soils with low bearing
capacity as they can spread the loads over a larger area.
In laying of raft foundation, special care is taken in the reinforcement and
construction of plinth beams and columns. It is the main portion on which
ultimately whole of the structure load is to come. So a slightest error can cause
huge problems and therefore all this is checked and passed by the engineer in
charge of the site.
17
Apart from raft foundation, individual footings were used in the mess area
which was extended beyond the C and D blocks.
CEMENT
Portland cement is composed of calcium silicates and aluminate and
aluminoferrite It is obtained by blending predetermined proportions limestone
clay and other minerals in small quantities which is pulverized and heated at
high temperature – around 1500 deg centigrade to produce ‘clinker’. The
18
clinker is then ground with small quantities of gypsum to produce a fine
powder called Ordinary Portland Cement (OPC). When mixed with water, sand
and stone, it combines slowly with the water to form a hard mass called
concrete. Cement is a hygroscopic material meaning that it absorbs moisture In
presence of moisture it undergoes chemical reaction termed as hydration.
Therefore cement remains in good condition as long as it does not come in
contact with moisture. If cement is more than three months old then it should
be tested for its strength before being taken into use.
The Bureau of Indian Standards (BIS) has classified OPC in three different
grades The classification is mainly based on the compressive strength of
cement-sand mortar cubes of face area 50 cm2 composed of 1 part of cement
to 3 parts of standard sand by weight with a water-cement ratio arrived at by a
specified procedure. The grades are
(i) 33 grade
(ii) 43 grade
(iii) 53 grade
The grade number indicates the minimum compressive strength of cement
sand mortar in N/mm2 at 28 days, as tested by above mentioned procedure.
Portland Pozzolana Cement (PPC) is obtained by either intergrinding a
pozzolanic material with clinker and gypsum, or by blending ground pozzolana
with Portland cement. Nowadays good quality fly ash is available from Thermal
Power Plants, which are processed and used in manufacturing of PPC.
ADVANTAGES OF USING PORTLAND POZZOLANA CEMENT OVER OPC
Pozzolana combines with lime and alkali in cement when water is added and
forms compounds which contribute to strength, impermeability and sulphate
resistance. It also contributes to workability, reduced bleeding and controls
destructive expansion from alkali-aggregate reaction. It reduces heat of
hydration thereby controlling temperature differentials, which causes thermal
strain and resultant cracking n mass concrete structures like dams. The colour
of PPC comes from the colour of the pozzolanic material used. PPC containing
fly ash as a pozzolana will invariably be slightly different colour than the OPC.
One thing should be kept in mind that is the quality of cement depends upon
the raw materials used and the quality control measures adopted during its
manufacture, and not on the shade of the cement. The cement gets its colour
from the nature and colour of raw materials used, which will be different from
factory to factory, and may even differ in the different batches of cement
produced in a factory. Further, the colour of the finished concrete is affected
also by the colour of the aggregates, and to a lesser extent by the colour of the
19
cement. Preference for any cement on the basis of colour alone is technically
misplaced.
SETTLING OF CEMENT
When water is mixed with cement, the paste so formed remains pliable and
plastic for a short time. During this period it is possible to disturb the paste and
remit it without any deleterious effects. As the reaction between water and
cement continues, the paste loses its plasticity. This early period in the
hardening of cement is referred to as ‘setting’ of cement.
INITIAL AND FINAL SETTING TIME OF CEMENT
Initial set is when the cement paste loses its plasticity and stiffens
considerably. Final set is the point when the paste hardens and can sustain
some minor load. Both are arbitrary points and these are determined by Vicat
needle penetration resistance
Slow or fast setting normally depends on the nature of cement. It could also be
due to extraneous factors not related to the cement. The ambient conditions
play an important role. In hot weather, the setting is faster, in cold weather,
setting is delayed Some types of salts, chemicals, clay, etc if inadvertently get
mixed with the sand, aggregate and water could accelerate or delay the setting
of concrete.
STORAGE OF CEMENT
It needs extra care or else can lead to loss not only in terms of financial loss but
also in terms of loss in the quality. Following are the don’t that should be
followed -
20
(i) Do not store bags in a building or a godown in which the walls, roof and
floor are not completely weatherproof.
(ii) Do not store bags in a new warehouse until the interior has thoroughly
dried out.
(iii) Do not be content with badly fitting windows and doors, make sure they fit
properly and ensure that they are kept shut.
(iv) Do not stack bags against the wall. Similarly, don’t pile them on the floor
unless it is a dry concrete floor. If not, bags should be stacked on wooden
planks or sleepers.
(v) Do not forget to pile the bags close together
(vi) Do not pile more than 15 bags high and arrange the bags in a header-and-
stretcher fashion.
(vii) Do not disturb the stored cement until it is to be taken out for use.
(viii) Do not take out bags from one tier only. Step back two or three tiers.
(ix) Do not keep dead storage. The principle of first-in first-out should be
followed in removing bags.
(x) Do not stack bags on the ground for temporary storage at work site. Pile
them on a raised, dry platform and cover with tarpaulin or polythene sheet.
COARSE AGGREGATE
Coarse aggregate for the works should be river gravel or crushed stone .It
should be hard, strong, dense, durable, clean, and free from clay or loamy
admixtures or quarry refuse or vegetable matter. The pieces of aggregates
should be cubical, or rounded shaped and should have granular or crystalline
or smooth (but not glossy) non-powdery surfaces. Aggregates should be
properly screened and if necessary washed clean before use.
Coarse aggregates containing flat, elongated or flaky pieces or mica should be
rejected. The grading of coarse aggregates should be as per specifications of IS-
383.
After 24-hrs immersion in water, a previously dried sample of the coarse
aggregate should not gain in weight more than 5%.
Aggregates should be stored in such a way as to prevent segregation of sizes
and avoid contamination with fines.
Depending upon the coarse aggregate color, there quality can be determined
as:
Black => very good quality
Blue => good
Whitish =>bad quality
21
FINE AGGREGATE
Aggregate which is passed through 4.75 IS Sieve is termed as fine aggregate.
Fine aggregate is added to concrete to assist workability and to bring
uniformity in mixture. Usually, the natural river sand is used as fine aggregate.
Important thing to be considered is that fine aggregates should be free from
coagulated lumps.
Grading of natural sand or crushed stone i.e. fine aggregates shall be such that
not more than 5 percent shall exceed 5 mm in size, not more than 10% shall IS
sieve No. 150 not less than 45% or more than 85% shall pass IS sieve No. 1.18
mm and not less than 25% or more than 60% shall pass IS sieve No. 600
micron.
BRICKWORK
Brickwork is masonry done with bricks and mortar and is generally used to
build partition walls. In our site, all the external walls were of concrete and
most of the internal walls were made of bricks. English bond was used and a
ration of 1:4 (1 cement: 4 coarse sand) and 1:6 were used depending upon
whether the wall is 4.5 inches or 9 inches. The reinforcement shall be 2 nos.
M.S. round bars or as indicated. The diameter of bars was 8mm. The first layer
of reinforcement was used at second course and then at every fourth course of
brick work. The bars were properly anchored at their ends where the portions
and or where these walls join with other walls. The in laid steel reinforcement
was completely embedded in mortar.
Bricks can be of two types. These are:
1) Traditional Bricks-The dimension if traditional bricks vary from 21 cm to
25cm in length,10 to 13 cm in width and 7.5 cm in height in different parts of
country .The commonly adopted normal size of traditional brick is 23 *
11.5*7.5 cm with a view to achieve uniformity in size of bricks all over country.
2) Modular Bricks- Indian standard institution has established a standard size
of bricks such a brick is known as a modular brick. The normal size of brick is
taken as 20*10*10 cm whereas its actual dimensions are 19*9*9 cm masonry
with modular bricks workout to be cheaper there is saving in the consumption
of bricks, mortar and labour as compared with masonry with traditional bricks.
STRENGTH OF BRICK MASONRY
The permissible compressive stress in brick masonry depends upon the
following factors:
1. Type and strength of brick.
2. Mix of motor.
3. Size and shape of masonry construction.
22
The strength of brick masonry depends upon the strength of bricks used in the
masonry construction. The strength of bricks depends upon the nature of soil
used for making and the method adopted for molding and burning of bricks
.since the nature of soil varies from region to region ,the average strength of
bricks varies from as low as 30kg/sq cm to 150 kg /sq cm the basic compressive
stress are different crushing strength.
There are many checks that can be applied to see the quality of bricks used on
the site. Normally the bricks are tested for Compressive strength, water
absorption, dimensional tolerances and efflorescence. However at small
construction sites the quality of bricks can be assessed based on following,
which is prevalent in many sites.
• Visual check – Bricks should be well burnt and of uniform size and colour.
• Striking of two bricks together should produce a metallic ringing sound.
• It should have surface so hard that can’t be scratched by the fingernails.
• A good brick should not break if dropped in standing position from one metre
above ground level.
• A good brick shouldn’t absorb moisture of more than 15-20% by weight,
when soaked in water For example; a good brick of 2 kg shouldn’t weigh
more than 2.3 to 2.4 kg if immersed in water for 24 hours.
PRECAUTIONS TO BE TAKEN IN BRICK MASONRY WORK
• Bricks should be soaked in water for adequate period so that the water
penetrates
to its full thickness. Normally 6 to 8 hours of wetting is sufficient.
• A systematic bond must be maintained throughout the brickwork. Vertical
joints
23
shouldn’t be continuous but staggered.
• The joint thickness shouldn’t exceed 1 cm. It should be thoroughly filled with
the
cement mortar 1:4 to 1:6 (Cement: Sand by volume)
• All bricks should be placed on their bed with frogs on top (depression on top
of the
brick for providing bond with mortar).
• Thread, plumb bob and spirit level should be used for alignment, verticality
and
horizontality of construction.
• Joints should be raked and properly finished with trowel or float, to provide
good bond.
• A maximum of one metre wall height should be constructed in a day.
• Brickwork should be properly cured for at least 10 days
REINFORCEMENT
Steel reinforcements are used, generally, in the form of bars of circular cross
section in concrete structure. They are like a skeleton in human body. Plain
concrete without steel or any other reinforcement is strong in compression but
weak in tension. Steel is one of the best forms of reinforcements, to take care
of those stresses and to strengthen concrete to bear all kinds of loads
Mild steel bars conforming to IS: 432 (Part I) and Cold-worked steel high
strength deformed bars conforming to IS: 1786 (grade Fe 415 and grade Fe
500, where 415 and 500 indicate yield stresses 415 N/mm2 and 500 N/mm2
respectively) are commonly used. Grade Fe 415 is being used most commonly
nowadays. This has limited the use of plain mild steel bars because of higher
yield stress and bond strength resulting in saving of steel quantity. Some
companies have brought thermo mechanically treated (TMT) and corrosion
resistant steel (CRS) bars with added features.
Bars range in diameter from 6 to 50 mm. Cold-worked steel high strength
deformed bars start from 8 mm diameter. For general house constructions,
bars of diameter 6 to 20 mm are used
Transverse reinforcements are very important. They not only take care of
structural requirements but also help main reinforcements to remain in
desired position. They play a very significant role while abrupt changes or
reversal of stresses like earthquake etc.
They should be closely spaced as per the drawing and properly tied to the
main/longitudinal reinforcement
TERMS USED IN REINFORCEMENT
24
BAR-BENDING-SCHEDULE
Bar-bending-schedule is the schedule of reinforcement bars prepared in
advance before cutting and bending of rebars. This schedule contains all details
of size, shape and dimension of rebars to be cut.
LAP LENGTH
Lap length is the length overlap of bars tied to extend the reinforcement
length.. Lap length about 50 times the diameter of the bar is considered safe.
Laps of neighboring bar lengths should be staggered and should not be
provided at one level/line. At one cross section, a maximum of 50% bars
should be lapped. In case, required lap length is not available at junction
because of space and other constraints, bars can be joined with couplers or
welded (with correct choice of method of welding).
ANCHORAGE LENGTH
This is the additional length of steel of one structure required to be inserted in
other at the junction. For example, main bars of beam in column at beam
column junction, column bars in footing etc. The length requirement is similar
to the lap length mentioned in previous question or as per the design
instructions
COVER BLOCK
Cover blocks are placed to prevent the steel rods from touching the shuttering
plates and there by providing a minimum cover and fix the reinforcements as
per the design drawings. Sometimes it is commonly seen that the cover gets
misplaced during the concreting activity. To prevent this, tying of cover with
steel bars using thin steel wires called binding wires (projected from cover
surface and placed during making or casting of cover blocks) is recommended.
Covers should be made of cement sand mortar (1:3). Ideally, cover should have
strength similar to the surrounding concrete, with the least perimeter so that
chances of water to penetrate through periphery will be minimized. Provision
of minimum covers as per the Indian standards for durability of the whole
structure should be ensured.
Shape of the cover blocks could be cubical or cylindrical. However, cover
indicates thickness of the cover block. Normally, cubical cover blocks are used.
As a thumb rule, minimum cover of 2” in footings, 1.5” in columns and 1” for
other structures may be ensured.
Structural element Cover to reinforcement (mm)
Footings 40
Columns 40
Slabs 15
25
Beams 25
Retaining wall 25 for earth face
20 for other face
THINGS TO NOTE
Reinforcement should be free from loose rust, oil paints, mud etc. it should be
cut, bent and fixed properly. The reinforcement shall be placed and maintained
in position by providing proper cover blocks, spacers, supporting bars, , laps
etc. Reinforcements shall be placed and tied such that concrete placement is
possible without segregation, and compaction possible by an immersion
vibrator.
For any steel reinforcement bar, weight per running meter is equal to d*d/162
Kg, where d is diameter of the bar in mm. For example, 10 mm diameter bar
will weigh 10×10/162 = 0.617 Kg/m
Three types of bars were used in reinforcement of a slab. These include
straight bars, crank bar and an extra bar. The main steel is placed in which the
straight steel is binded first, then the crank steel is placed and extra steel is
placed in the end. The extra steel comes over the support while crank is
encountered at distance of ¼(1-distance between the supports) from the
surroundings supports.
For providing nominal cover to the steel in beam, cover blocks were used
which were made of concrete and were casted with a thin steel wire in the
center which projects outward. These keep the reinforcement at a distance
from bottom of shuttering. For maintaining the gap between the main steel
and the distribution steel, steel chairs are placed between them
SHUTTERING AND SCAFFOLDING
DEFINITION
The term ‘SHUTTERING’ or ‘FORMWORK’ includes all forms, moulds, sheeting,
shuttering planks, walrus, poles, posts, standards, leizers, V-Heads, struts, and
structure, ties, prights, walling steel rods, bolts, wedges, and all other
temporary supports to the concrete during the process of sheeting.
26
FORM WORK
Forms or moulds or shutters are the receptacles in which concrete is placed, so
that it will have the desired shape or outline when hardened. Once the
concrete develops adequate strength, the forms are removed. Forms are
generally made of the materials like timber, plywood, steel, etc.
Generally camber is provided in the formwork for horizontal members to
counteract the effect of deflection caused due to the weight of reinforcement
and concrete placed over that. A proper lubrication of shuttering plates is also
done before the placement of reinforcement. The oil film sandwiched between
concrete and formwork surface not only helps in easy removal of shuttering
but also prevents loss of moisture from the concrete through absorption and
evaporation.
The steel form work was designed and constructed to the shapes, lines and
dimensions shown on the drawings. All forms were sufficiently water tight to
prevent leakage of mortar. Forms were so constructed as to be removable in
sections. One side of the column forms were left open and the open side filled
in board by board successively as the concrete is placed and compacted except
when vibrators are used. A key was made at the end of each casting in
concrete columns of appropriate size to give proper bondings to columns and
walls as per relevant IS.
27
CLEANING AND TREATMENT OF FORMS
All rubbish, particularly chippings, shavings and saw dust, was removed from
the interior of the forms (steel) before the concrete is placed. The form work in
contact with the concrete was cleaned and thoroughly wetted or treated with
an approved composition to prevent adhesion between form work and
concrete. Care was taken that such approved composition is kept out of
contact with the reinforcement.
DESIGN
The form-work should be designed and constructed such that the concrete can
be properly placed and thoroughly compacted to obtain the required shape,
position, and levels subject
ERECTION OF FORMWORK
The following applies to all formwork:
a) Care should be taken that all formwork is set to plumb and true to line and
level.
b) When reinforcement passes through the formwork care should be taken to
ensure close
fitting joints against the steel bars so as to avoid loss of fines during the
compaction of
concrete.
c) If formwork is held together by bolts or wires, these should be so fixed that
no iron is
exposed on surface against which concrete is to be laid.
28
d) Provision is made in the shuttering for beams, columns and walls for a port
hole of
convenient size so that all extraneous materials that may be collected could be
removed just prior to concreting.
e) Formwork is so arranged as to permit removal of forms without jarring the
concrete.
Wedges, clamps, and bolts should be used where practicable instead of nails.
f) Surfaces of forms in contact with concrete are oiled with a mould oil of
approved
quality. The use of oil, which darkens the surface of the concrete, is not
allowed. Oiling
is done before reinforcement is placed and care taken that no oil comes in
contact with
the reinforcement while it is placed in position. The formwork is kept
thoroughly wet
during concreting and the whole time that it is left in place.
Immediately before concreting is commenced, the formwork is carefully
examined to ensure the following:
a) Removal of all dirt, shavings, sawdust and other refuse by brushing and
washing.
b) The tightness of joint between panels of sheathing and between these and
any hardened core.
c) The correct location of tie bars bracing and spacers, and especially
connections of
bracing.
d) That all wedges are secured and firm in position.
e) That provision is made for traffic on formwork not to bear directly on
reinforcement
steel.
VERTICALITY OF THE STUCTURE
All the outer columns of the frame were checked for plumb by plumb-bob as
the work proceeds to upper floors. Internal columns were checked by taking
measurements from outer row of columns for their exact position. Jack were
used to lift the supporting rods called props
STRIPPING TIME OR REMOVAL OF FORMWORK
Forms were not struck until the concrete has attained a strength at least twice
the stress to which the concrete may be subjected at the time of removal of
form work. The strength referred is that of concrete using the same cement
29
and aggregates with the same proportions and cured under conditions of
temperature and moisture similar to those existing on the work. Where so
required, form work was left longer in normal circumstances
Form work was removed in such a manner as would not cause any shock or
vibration that would damage the concrete. Before removal of props, concrete
surface was exposed to ascertain that the concrete has sufficiently hardened.
Where the shape of element is such that form work has re-entrant angles, the
form work was removed as soon as possible after the concrete has set, to
avoid shrinkage cracking occurring due to the restraint imposed. As a guideline,
with temperature above 20 degree following time limits should be followed:
Structural Component Age
Footings 1 day
Sides of beams, columns, lintels, wall 2 days
Underside of beams spanning less than 6m 14 days
Underside of beams spanning over 6m 21 days
Underside of slabs spanning less than 4m 7 days
Underside of slabs spanning more than 4m 14 days
Flat slab bottom 21 days
30
side view and main entrance area
front view near flag mast
1.5 PHOTO GALLERY
DOWN THE LINE……..
31
During HON. Chairman’s visit
on the verge of completion (dec. ’13)
32
1.6 Conclusion
This building with a build-up area of 2,47,150SFT is both
structurally sound and environment friendly.
Also to say the least, this represents the ideology of jspl i.e. to go
green. Steel beams at some places are not covered with the
convensional false ceiling just to show the beauty of steel.
Also,on getting into the intricatilies of civil engineering its aparent
that maintaining a safe environment for work is equally as important
as other attributes.
SAFETY AT CONSTRUCTION SITE SHOULD BE PAID UTMOST
SIGNIFICANCE.
Supervised by-
…………………………………..
Mr. Ashok A. Gunjal
( ) mentored by-
……………………………….
Mr. Sandeep kumar Sahoo
(manager,civil deptt,jspl)
33
CHAPTER-2
2.1 INTRODUCTION
Recently JSPL has arised with revolutionary and innovative technique
to eliminate the outdated conventional flooring system with
suspended concrete flooring system known as ‘Jindal Speedfloor’.
The manufacturing facility for Jindal Speedfloor is located 30kms
away from the heart of Raigarh City, Chattisgarh at O.P. Jindal
Knowledge Park,Punjipatra
SPEEDFLOOR, the unique suspended concrete flooring system, is an innovation
in the building industry.
Speedfloor at parsada,raigarh
34
So quick and easy to install, SPEEDFLOOR is a lightweight, cost-effective
system that's perfect for multi-storey buildings and carparks. Whether it's one
storey or fifteen, the recipe is very simple,take sufficient quantity of
SPEEDFLOOR, add structural steel or concrete supports, mix concrete and
pourl at the heart of the system is a specially rollformed, galvanised steel joist
that offers all the benefits of an open-webbed truss system at a more enough
to be man- handled into place, reducing cranaage costs.
Services are easily accommodated through the joists which are delivered to
the site ready to install.
SPEEDFLOOR The perfectly simple, simply perfect solution to multi-storey
construction.
35
SPEED FLOORING Let us introduce you to a revolution in suspended concrete flooring which is, a) Faster b) Lighter c) Easier SPEED FLOOR is a unique and innovative suspended concrete flooring system combining a light gauge rollformed steel joist compositely with an insitu concrete topping System to form a material efficient and cost effective concrete floor.
Speedfloor is a suspended concrete flooring system using a rollformed steel joist as an integral part of the final concrete and steel composite floor.The system has been developed combining modern techniques and rollforming technology for a fast, lightweight, concrete/steel composite floor at a cost-effective price. The joist is manufactured from pre-galvanized high tensile steel in a one pass rollformer, where it is rollformed, punched, slotted to a high degree of accuracy at a fast production rate. The ends are simply bolted to the joist which are then ready for shipping to site. No curing, no painting, no hassles. The individually marked, lightweight joists are placed on the support medium .The reinforcement is placed and the concrete floor is ready to pour. The Speedfloor composite floor system is suitable for use in all types of construction, i.e. steel frame structures, masonry buildings, poured in-situ or precast concrete frames as well as wooden frame construction, from single family detached houses to multi-story residential and office complexes. Speedfloor uses a rollformed steel joist for permanent
36
structural support, using the properties of the concrete and steel to their best advantage. The joist depth and the concrete thickness are varied depending on the span, imposed loads and other functional considerations. 2.2 ADVANTAGES A number of the more important advantages of Speedfloor are listed below: (a) Generally Speedfloor uses a 75mm or 90mm topping. A general weight saving can be made throughout the structural components of the building. (b) The joists are lightweight, requiring less craneage than other concrete flooring systems. (c) The Speedfloor joists are custom manufactured to suit particular job conditions. It is important to remember that the Speedfloor joist modular spacing can be adjusted to suit varying conditions. (d) During construction, the Speedfloor system provides a rigid working platform. (e) Shallower floor depths can be achieved because of the increased rigidity of the system. (f) Services can be passed through the holes pre-punched in the joist.. (g) The bottom of the joist can support a suspended fire rated ceiling directly fixed to the joist. (h) The lockbars and plywood sheets are reusable. - The System - Accessories - How it works - Design - Price comparison - Project example THE SYSTEM i) The Speedfloor joist and the formwork system was designed and exhaustively tested in New Zealand before its introduction into the global
37
market place. ii) The Speedfloor system and any associated intellectual property are owned by Speedfloor Ltd. THE JOIST :- At the heart of the system is a rollformed, galvanised steel joist.
a)The joist is manufactured from pre-galvansied, high tensile steel in a rollformer where in a single integrated operation, it is rollformed, punched, pressed, pre-cambered, and cut to length at a fast production rate. b)The shoe are simply bolted to the joists which are then ready to ship. c)They can be palletized, containerised or loaded onto transport for direct delivery to site.
38
d)The individually marked joists, strapped in bundles, are lifted onto the support medium where they can safely remain until required. e)The joists are then spread and locked into their final positions with use of lockbars. Plywood forms are introduced from the top to form the slab shuttering system. -The reinforcement is now ready to place. The top section of the joist supports the reinforcement and becomes embedded in the concrete topping for composite action. -The cam action of the lockbar tightens the ply formwork against the Joist giving a clean and generally slurry free joint meaning little or no cleanup is required.
-Three days after the concrete is poured the shutter system is removed revealing a clean fresh suspended concrete floor. Services can pass through the prepunched holes and the bottom of the joist can support a suspended fir-rated ceiling directly fixed to the joist. 2.3 HOW IT WORKS The Joist The top section of the joist that becomes embedded into the concrete slab has 4 functions: • It is the compression element of the non-composite joist during
39
Construction. • It is the chair or stool that supports the wire mesh or the reinforcement that develops negative moment capacity in the concrete slab over the joist. • It locks in and supports the slab shuttering system. • It becomes a continuous shear connector for the composite system. • The mid section or web of the joists has the flanged service hole and the lockbar hole punched into it The flanging of the service hole provides stability to the web and services can pass thru without requiring protection from the sharp edges of the punched material. The 60mm by 25mm diameter lockbar holes are punched at 150mm pitch to receive the lockbars and afford evenly distributed support for the plywood • The bottom triangular section of the joist acts as a tension member both during the construction phase and when the joist is acting compositely with the slab. The Lockbar • The lockbars support the temporary plywood formwork between the joists during construction. They are spaced approximately 300mm apart and engage in the slotted holes punched in the top section of the joist. They also maintain the exact spacing of the joist. • The standard lockbars when installed will position the joists 1230mm, 930mm or 630mm apart. There are also special adjustable lockbars that will position the joists in increments of 50mm from 330mm up to 1530mm. Other types of lockbars provide for special situations such as cantilevers or lowered soffits. Temporary Plywood Formwork • High-density paper overlaid, 12mm plywood is used as formwork to produce a first class finish to the underside of the slab.
40
• The rigid plywood sheets are used in conjunction with the lockbars and when locked in place, provide lateral stability to the entire Speedfloor system during the construction phase. Support Medium The Speedfloor composite floor system is suitable for use in all types of construction including: • Steel frames structures • Masonary buildings • Poured insitu or precast concrete frames • ICF or polystyrene construction • Light gauge steel frames • Timber frames The range of ends users includes: • Single family detached homes • Multi-storey residential blocks • Single and multi-storey retail developments • Mezzinine floors • Carpark and storage buildings • Multi-storey office complexes ACCESSORIES Edge Angles A standard edge form is available in two heights (90mm & 75mm). Special heights and specially shaped edge angles can be manufactured but require longer lead times. Jointers Precut sections of galvanized sheet steel can be supplied to overlay joints in the ply to ensure they are flush and remain well supported while the concrete is poured.
41
Lockbar Hanger Angles A galvanized steel angle with pre-punched lockbar holes is available for situations where the lockbars need support on slab edges parallel to the joists.
2.4 DESIGN
• The Speedfloor System is essentially a hybrid concrete/ steel tee-beam in one direction and an integrated continuous one-way slab in the other. • The joist is manufactured from G350mPa, Z275 pre galvanised steel. • The rollformed shape with its pressed web produces a rigid and accurate steel section that has high load carrying capacity with no propping requirements. Acoustics The performance of the Speedfloor slab is similar to that of a conventional insitu poured slab.
42
To achieve STC 55 or more a board system on a timber or steel grid can be attached directly to the underside of the joist. Alternatively the concrete topping can be increased until the required rating is achieved. Seismic The general arrangement of the joist and the shoe end together create a number of very real advantages for the Speedfloor system in seismic regions. Seizmic design promotes relatively rigid interconnection of elements under normal conditions and flexible connection when subjected to seismic disturbance. It is absolutely imperative that the floor/beam connection does not induce moments into other elements of the structure that would compromise the integrity of the structure. • The use of a ‘pin-jointed’ or ‘simply–supported’ connection between the concrete floor and the support structure allows the Speedfloor to flex without shearing preventing catastrophic collapse. The shoe will remain as a failsafe mechanism on top of the support medium. Reinforcement bars connected to the structure prevent horizontal displacement of the concrete floor. • The Speedfloor system generally uses much less concrete than precast or insitu concrete alternatives and hence has less mass. Under seismic conditions mass creates inertial force so less mass means less inertial force which can dramatically limit damage. • As a ductile suspended concrete floor incorporating a relatively high percentage of steel, Speedfloor is ideally placed to help dissipate the dynamic shock involved in seismic loading. • Speedfloor has the ability to act as a diaphragm and transfer the lateral forces through the floor to the shear walls located in other parts of the building. Fire Full scale fire testing has established that the Speedfloor system can be fire rated and will meet fire rating requirements set out in the Building Code. Option for fire protection are numerous but will include:
43
• The use of fire retardant boards including gypsum and other cementitious board systems. • Sprayed cementitious products directly onto the Speedfloor joist. • The addition of reinforcement to the concrete topping using the Slab Panel Method or other engineered design methods.
2.5 PRICE COMPARISON
This real example will show how to save up to 25% per sqm on your Floor/structure cost by refining the steel structure and using thislightweight, innovative flooring system. Notes • Casino Apartments in New Zealand have been chosen to best illustrate visually the application of Speedfloor. • For the sake of comparing a profiled floor decking system and the Speedfloor flooring system, only part of a typical floor from the project has been selected and analysed in detail. • In each case the columns and bracing are considered to be common to both systems, as is the pumping and placing of the concrete. • Handrails, perimeter scaffolding, cranage, step-downs, openings, etc are all considered as common to both systems. i)Profiled Flooring System Structure
44
Primary Beams 460UB67 48.8m = 3.269T 360UB51 16.6m = 0.847T Secondary Beams 360UB51 49.8m = 2.540T Total tonnage = 6.656T Total Structure Cost @ $3500/T $23,296 Profiled Floor: Supplied and Installed 267.3sq m @ $55.00/ m2 $14,701 Concrete 105mm thick @ $195.00/ m3 $ 5,473 Placing @ 4.50/ m2 $ 1,203 Mesh @ $5.80/ m2 $ 1,550 Total Floor For Comparison $46,223 ii)Speedfloor Flooring System Structure
Primary Beams 460UB67 48.8m = 3.269T 360UB51 16.6m = 0.847T Secondary Beams Not req. Total tonnage 3.269T
45
Total Structure Cost @ $3500/T $11,441 Add Speedfloor Joists 193.3 m @ $46 / m $ 8,891 Total Structure incl. Speedfloor $20,332 Speedfloor Installation 267.3 m @ $16.80/ m2 $4,410 Concrete 90mm thick @ $195.00/ m3 $4,691 Placing @ 4.50/ m2 $1,202 Mesh @ $5.80/ m2 $1,550 Hire of lockbars and plywood $2,842 Total Floor For Comparison $35,027 SUMMARY Profiled Flooring System Total Structure Cost @ $3800/T $25,292 Total Flooring Cost $22,927 Total Floor For Comparison $46,223 Speedfloor Flooring System Total Structure incl. Speedfloor $21,313 Total Speedfloor flooring cost $14,695 Total Floor For Comparison $35,027 A saving of $41.88/ m2 or approx 24% DESIGN • Speedfloor rollformed joists are made from high strength, pre-galvanised steel. • Concrete slab topping designed for minimum compressive strength of 25MPa after 28 days. • Floor system design conforms to Composite Structure Standards.
46
• Durability meets Building Codes’ performance criteria. STANDARD DETAILS i)200 Series
ii)250 Series
iii)400 Series
47
STANDARD SHOE DETAIL
48
STEEL BEAM SUPPORT
MASONRY WALL SUPPORT
49
LOAD SPAN
DURABILITY & MAINTENANCE Compliance When supplied and installed in accordance with the manufacturer's specifications and design parameters, the SPEEDFLOOR suspended concrete flooring system can reasonably be expected to meet the performance criteria set out in clause B2, Durability of the New Zealand
50
Building Code for a period of 50 years. Serviceable Life Speedfloor is a composite floor system using both steel and concrete. The two elements must be treated and maintained separately.
2.6 SPECIFICATION
2.6.1) GENERAL 2.6.1.1)Scope Supply and Installation a) Speedfloor or the Speedfloor Agent shall supply all steel joists, components, labour, material and equipment relating to the installation of the Speedfloor suspended concrete floor system. Speedfloor steel joists and lockbars shall be manufactured and marked by Speedfloor Holdings Ltd, or their authorised agent. Supply only b) Speedfloor or the Speedfloor Agent shall supply all steel joists and components relating to the Speedfloor suspended concrete floor system. Speedfloor steel joists and lockbars shall be manufactured and marked by Speedfloor Holdings Ltd, or their authorised agent. 2.6.2) TYPICAL SPECIFICATION 2.6.2.1)Design Principle The design of the Speedfloor System is based on NZS 3404: Part 1 and 2 1997, AS/NZS 4600:1996, and the Australian Composite Structures Standard AS 2327, Part 1. The design loads are in accordance with AS/NZS1170:2202 parts 0 and 1, Structural Design Actions. 2.6.2.2)Design Parameters • The section properties and design parameters are calculated from the section geometry, supplementary full-scale tests and finite element analysis. • Speedfloor joists have flanged service holes in the web to assist in web stiffening and to provide practical services access. The joist is simply supported during construction generally with no propping required. The
51
concrete is cast in place and acts compositely with the Speedfloor joist. 2.6.2.3)Materials • Speedfloor joists are rollformed from zinc coated steel coil conforming to AS 1397. The minimum mass coating of galvanizing is 275g/m2. • The standard steel used is Grade 350 and has a minimum yield stress of 350MPa and a minimum tensile stress of 380MPa. • The concrete slab decking requires a minimum compressive strength of 25MPa (30MPa for carparks) in 28 days and the steel mesh is high tensile cold drawn wire to NZS 3422:1975. 2.6.3)FIRE 2.6.3.1)Speedfloor Fire Rating Full scale fire testing has established that the Speedfloor system can be fire rated and meet fire rating requirements set out in the Building Code. Options for fire protection include: • Using a fire rated ceiling (30, 60 & 90 min) • Using sprayed cementitious products directly onto Speedfloor joist (30, 60 & 90 min) • Intumescent paint products directly on Speedfloor joist.(30,60& 90 min) • The addition of reinforcement to the concrete topping using the SPM design method (see 3-2 SPM Program) • Further technical information including tests is available on request. 2.6.3.2)SPM Program An alternative design procedure invoiving the addition of in-slab reinforcement can be used for floor slabs exposed to moderate or severe fire conditions. This procedure is based on quantifying the tensile membrane enhancement provided by in-slab reinforcement
52
2.7 PROJECT EXAMPLE
a)Route 66,Broadways
• This 7 storey building was constructed using a structural steel frame, Speedfloor suspended concrete flooring system and precast concrete cladding. •The ground floor retail has exposed Speedfloor joists fireproofed using intumescent paint. • The store’s services, such as electrical cabling, have been accommodated through the exposed joists.
53
b)Commerce St Carpark
•The lightweight nature of the Speedfloor and Structural Steel combination resulted in minimal foundations and a 16 week building program for this 10 storey carpark. •The ramp structure is cantilevered over the existing building next door via
54
trusses on the roof which required the carpark decks to be in place before the ramps decks could be built. c)Grafton Carpark
•This 22,000 m2 (220,000 ft2) carpark is staff and patient parking for Auckland Hospital. • The lightweight steel structure also accommodates three helicopter pads on the top floor. d)Dilworth Building This commercial two storey building with basement carparking was designed for a Blood-bank and commercial use.
55
e)Watt St Carpark •This 3 level carpark was originally built as only one suspended level of Speedfloor. •The system and speed of erection so impressed the owner that he added another two levels almost immediately.
56
2.8 Conclusion FASTER-LIGHTER-EASIER Summary of important advantages • Cost effective • Lightweight, requiring less cranage than other systems • Speed of erection • Easily accommodates services • Meets fire and acoustic requirements • Flexible in its application • No Propping • A general weight saving throughout structural Components
As already discussed, SPEEDFLOORis a revolutionary and an excellent
alternative of conventional brick mortar buildings.
SPEEDFLOOR, the unique suspended concrete flooring system, is an innovation
in the building industry
SPEEDFLOOR The perfectly simple, simply perfect solution to multi-storey
construction.
Supervised by-
………………………………….
Mr. A K Saini
(manager civil deptt.,jspl)
mentored by-
………………………………..
Mr. Dibyagan Das
(manager civil deptt.,jspl)
57
Chapter 3-
3.1 INTRODUCTION In India, in step with progressively increasing the capacity of coal-fired thermal
power plants, the amount of fly ash generated is increasing very fast. Increase
in number of coal based thermal power plant is also responsible for high
amount of generation of fly ash. The table given below shows data related to
its generation and use in different year.
Table:1 Fly ash generation and use in india
Year Generation (Mt)
Use (Mt)
% Use of generation
1993-94
40
1.2
3
2005-06
112
42
38
2006-07
130
60
46
2011-12
170
170
100 % use of mandated
2031-32 600 - not yet planned; innovation essential
The utilization of fly ash in India varies between 40-50% and rests are disposed and are restored. Fly ash storage require huge amount of land area. So to reduce the land wastage it is stored using ash dam construction. Ash dam is an important structure, located few kilometers away from the hydraulic power
ASH DYKE VISIT
58
stations for storing the coal ashes. Ash dam construction is continuous process and it is raised each step through dyke construction. Ash dam should construction is a great challenge for civil engineers as the failure of ash dam has an adverse effect on surrounding environment as well as it can affect the smooth functioning of power stations. It also causes havoc among the surrounding people about safety of their life. It causes economic losses. It pollutes the surrounding river water which is dangerous for aquatic life as well as human being. So ash dam should be constructed with proper safety and precautions.
fig: Breaching area due to failure of ash dam.
3.2 CONSTRUCTION OF ASH DYKE The construction of fly ash dyke is classified into three broad categories as
following;
1.Upstream construction method
2.Downstream construction method
3.Centerline construction method
59
UPSTREAM CONSTRUCTION METHOD
(a) This method is popularly used method as earth work required is minimum.However this method faces certain disadvantages: (b)The entire weight of new construction when dyke raised is supported on deposited ash., There is possibility of finer ash particles deposited along the bund if ash deposition is not carefully done . This results inadequate bearing capacity for support of the new dyke. (c) With increase in height of the pond the plan area of the pond reduces., It turnout to be uneconomical to raise the height further on this reason beyond a certain stage.
DOWNSTREAM CONSTRUCTION METHOD
(a)When the pond gets filled upto the first stage of construction, the pond height is further increased by depositing the earth / fly ash on the d/s face of the ash dyke. (b) There is possibility of raising the height of the pond even when the pond is operational However no reduction in the quantity of construction occurs which is same as the single stage construction. CENTER LINE CONSTRUCTION METHOD (a)Here after the pond gets filled upto the first stage, material is placed for raising height of the dyke on either side of centre line of the dyke so that the center line of the dyke falls at the same location. This necessiates a part of the
60
raw material to be placed on the deposited ash and part of the material on the down stream face of the existing ash dyke. (b)The earth work required in centreline method is less compared to that of in down stream method. But as the material is required to be deposited on the settled fly ash, it is not convenient to carry out the construction when the pond is operational.
(c)This method is suitable only if the total area of ash pond is fragmented into
compartments.
3.3 LAYOUT OF ASH DYKE OF JSPL,RAIGARH
fig: Layout Plan of Peripheral Dyke Raising Up to El 256m in Phase I
61
Details of cross section view of ash dyke
fig: SECTION F-F
fig: Typical cross section of Rock Toe.
62
3.4 FAILURE OF ASH DYKE AND INVESTIGATION REPORT
The failure of ash dyke may be due to various factors. Different people have
done different investigation in the field of ash dam failure. Failure of ash dyke
may take place due to following reasons:
a) Seepage of water
b) Stability of dikes
c) Soil properties in starter dyke,
d) Method of compaction
e) Absence of drainage filter.
After investigation of ash dam failure different study were carried out.
i. Study of the detail drawings, prior inspection report, safety issue and gain an understanding of the original design and modifications of the facility.
ii. Perform site visit and visual inspection at regular interval of time.
iii. Evaluation of the structural stability, quality and adequacy of the management unit’s inspection, maintenance and operation procedure.
iv. Identification of the critical structure in the surrounding environment.
v. Risk assessment.
Modification since original structure: a) Ash pond was constructed by raising the dyke over the previously deposited fly ash. The upper pond was constructed by using bottom ash excavated from ash complex. Geogrid is provided to add stability for the new embankments. Toe drain system is installed.
b) Piezometers are installed to control seepage.
c) Downstream slopes were reinforced with the vegetation to provide integral stability.
63
d) Provision of emergency rectangular concrete spillway.
MAXIMUM LAND REQUIRMENT FOR ASH DYKE (Government Of India,Ministry Of Power ) The land requirement for ash disposal depends on the capacity of the power station, ash content in the coal and also on the ash utilization in the area where the plant is located. The ash content in the coal being supplied to thermal power stations in the country is of the order of 40% except in cases where washed coal is used. Even the washed coal contains about 34% of ash. Accordingly, the amount of ash generated in a power station is of the order of 2 million tonnes per annum for 1000 MW plant capacity. Correspondingly the area required for ash disposal is also very large. MOE&F had specified that the fly ash utilization has to be 100% from 10th year of commissioning of the plant. Fly ash constitute about 80% of the total ash generated in a power plant. Fly ash utilization not only depends on the location of the power station but also on the agencies who are involved in this business. Since the power stations have no control over the agencies in the field of fly ash utilization, the task of 100% fly ash utilization is difficult in most of the cases. Therefore, the power station authorities have no alternative except to keep sufficient space for the ash disposal without which the power plant might have to be shut down after a few years of operation. The land requirement for the ash dyke is worked out based on the following criteria: a) PLF - - 90% b) Ash content in coal - -40% for units upto 660 MW/ 34% for 800 MW units based on Indian coal and 10% ash in imported coal c) Height of ash dyke - -18 metre (In stages) for pit head/load centre projects and 15metre for coastal projects d) Ash dyke shall be sufficient for 25 years of plant operation e) Bottom ash will be fully discharged into the dyke for 25 years of plant operation. f) Fly ash will be discharged starting with 10% utilization in the first
64
year and 100 % utilization during the 10th year. h) Unit Heat Rate - -2250 kCal/kWh. for 660/800 MW units
i) Calorific value of coal - -3600 kCal/kg for Indian coal and 6000
g) Density of ash in dyke - -1 T/m3
Based on the above criteria, the maximum area for the ash disposal for different station capacities are worked out and indicated in the table below. This maximum area takes into account the area for overflow lagoon, ash dyke
and dyke embankment. 50 m wide green belt is also to be provided all around the ash dyke. The maximum area has been worked out assuming that the site is in zone-3 and without clarifier for the ash water recovery. It is seen that the maximum area requirement per MW goes on reducing as the capacity of the station increases.
PLANT SIZE(MW)
2x500 3x660
5x660
6x660
4x800
5x800
Ash Storage Area
360
667
1148
1375
800
982
Embankment
39
57
67
70
53
60
Area of overflow Lagoons
25
30
30
50
40
50
Green Belt
76
101
125
135
107
118
Total Area
500
855
1370
1630
1000
1200
65
However, there is a considerable scope for reducing the land requirement for ash dyke by maximum utilization of Fly Ash as well as bottom ash.
3.5 ASH POND: HOW DO THEY FIT?
Decision of the layout of an ash pond should and must be guided by the following factors:
To reduce the pumping cost, the area should be close to the power plant. This is generally practiced all through. 2.There should be ample provisions for the vertical and horizontal expansion of the ash pond depending on the estimated life of the power plant. Although necessary, this criterion may not always be fully satisfied for all purposes. Although vertical expansion may not be difficult to attain, the possibility of horizontal expansion is always guided by the several factors, such as the availability of the land during the beginning of the construction, the probability of gaining extra space as construction and disposal progresses, whether the bearing capacity of the land is sufficient enough to sustain the progressively increasing load, and whether the vertical expansion made, if skewed, will be sustained by the basal formation. All these factors govern the nature of vertical expansion as a controlling parameter of the horizontal expansion (to be discussed in the next section). These factors, in turn, alleviate the challenges to the design on ash pond while maintaining its stability and safety. 3.The ash pond should be located far away water bodies comprising of rivers and lakes in order to prevent the contamination of the water bodies by pollutant transport from the pond due to seepage action. Although this is theoretically possible to say, practically it is a self-contradictory statement. Since the development of civilization and industrialization, sites near water bodies have always been lucrative, specifically due to one reason, i.e. the unhindered availability of water for myriads of purposes, whether be it domestic or industrial. Sufficient quantities of water are necessary to aid just in the cooling of the machineries.
66
So it is not at all surprising that many of the thermal power plants are located near water bodies. Care must be taken to prevent contamination and pollutant migration, the issue being constantly under the watchful eye of the Environmental Impact Assessment (EIA) authorities. 4.A primary requirement for choosing a favorable site for an ash pond rests with the availability of an impervious stratum to prevent migration of ash water into the ground water table. Such a situation can practically be called as a myth. A Geotechnologist or a Geologist will not agree more that such sites are referred as ideal, which ceases to exist to be found. Any site will be affected by varying degree of perviousness and different magnitudes of inclination of the bedding stratum. Hence, if unmonitored, slurry water is always going to seep in the ground. With the advent of geosynthetics and their profound applications, nowadays this leeching can be sufficiently controlled by the usage of geomembrane or utilizing composite geosynthetic clay liners beneath the area covered by ash pond. 5. It is preferable that the ash dykes be located near hilly terrains, so that the valley itself will serve as the ash dyke and would save significant amount of construction cost. However, although possible, one has to bear in mind that many such sites will provide free flowing water along the hill terrains and percolated water through the bedding channels which would add sufficient amount of water load in the ash dyke, causing over-saturation of the pond. If not controlled, this situation can significantly hamper the purpose and effectiveness of the site.
67
In most of the ash ponds, the total area available is divided into two or more compartments, so that at any instant of time, any one of the compartment can be in operation while the others are allowed to dry where the ash filling has already been completed. This allows for the rising in the ash dykes of the dried sectors while the other pocket is still functional, and hence, the flow and progress of the work is not hampered. An ash pond having a single pocket does not allow to be risen from its original height while it is operational. The area of the pond is also governed by the minimum time required for the settlement of the ash particle while the slurry travels from inlet to the outlet point. Theoretically, this is controlled by the Stoke’s law of particle settlement under terminal velocity.
3.6 RAISING METHODOLOGIES The increased embankment height, and the corresponding increase in the ash pond level, imposes greater load on existing embankment and foundation. At the same time, the pore pressure and seepage condition also gets significantly affected. The necessary design features associated with the raising of the embankment are: height of the embankment, crest width, side slope, compacted soil cover to preserve the compaction moisture content, graded filter to arrest piping and having suitable drain characteristic to reduce exit gradient, toe drain to evacuate the seepage water emanating from the foundation and dyke to control the development of excess pore-water pressure, and a trench drain to collect and dispose the emanated water. The suitability of existing filter and other drainage elements must be reevaluated and re-designed at various stages of raising to account for the change in the hydraulic conditions and phreatic line. Furthermore, compacted gravel drains can be installed below the proposed embankment to reduce the possibility of soil liquefaction during earthquake, and to accelerate the consolidation settlement with a target to improve the strength characteristics of the underlying soil. Unlike a water reservoir, the ash pond is generally constructed in stages, each raising having a height of 3-5m. The various methods of stage-wise construction are described here in: i)Upstream Raising This is the most preferred method of construction as the quantity of earthwork required is minimal. It provides better environmental pollution control compared to other methods since the constructed embankment being the final face of the ultimate embankment, vegetation and other fugitive dust control
68
and / or leachate control measures can be planned on the permanent basis. Operational requirements such as haul and access roads, culverts, diversion and perimeter ditches may be constructed easily to serve the entire useful life of facility. The starter dam, if properly designed, can be used as a toe filter for the entire embankment. However, this method has the following disadvantages:
fig: upstream raising of ash dykes. 1.The entire weight of the new construction for raising the dyke is supported on deposited ash. Unless the ash deposition is done carefully, finer ash particles deposited along the bund may result in significant lowering of the bearing capacity which may be hazardous for new dyke. 2.With the increased height of the pond, there is considerable lowering of the plan area of the pond. Beyond certain stage, it becomes uneconomical to raise further height of the dyke.
3.The drain provided on the upstream face needs to be suitable connected to the drain of the earlier segment. Improper design with regard to this issue can lead to the rising of the phreatic line and the stability of the slope may be endangered. 4.Since the entire segment of the new construction is supported on fly ash, it is important to carry out a liquefaction analysis and if necessary, suitable remediation measures should be adopted. 5.The pond needs to remain suspended from operation during the raising of the dyke. This is satisfactorily achieved without the stoppage of the slurry filling if sufficient number of compartments has been provided.
69
ii)Downstream Raising This method is most suitable for the construction of new embankments. In this method, the construction is carried out on the downstream side of the starter embankment, so that the crest of the dam is shifted progressively towards downstream and the starter dam forms the upstream toe of the final dam. This method has the following advantages: (i) None of the embankment is built on previously deposited ash, the extensions being placed on the previously constructed earth dam, and hence the issue of lowered baring capacity beneath the raisings does not come into picture. (ii) The placement and compaction control can be exercised as required over the entire fill operation. (iii) The embankment can be raised above its ultimate design height without any serious limitation and design modification, and (iv) In this case it is possible to raise the height of the pond even when the pond is in operation.
fig: downstream raising of ash dykes. iii)CENTERLINE RAISING The center line method is essentially a variation of the downstream method where the crest of the embankment is not shifted in the downward direction but raised in vertically upward above the crest of the starter dam. In this method, after the pond gets filled up to the first stage, material is placed for raising height of the dyke on either side of centre line of the dyke such that the center line of the dyke remains at the same location. This requires part of the raw material to be placed on the deposited ash and part of the material on the downstream face of the existing dyke. The earth work required in this case is less compared to the construction while downstream method. However, as the material is required to be deposited on the settled fly ash, it is not possible to carry out the construction when the pond is in operation. This method can be
70
adopted only if the total area of ash pond is divided into compartments. The
center line method leads to many design, construction, environmental and
operational problems and as such it is not generally used. At present, often
combinations of both upstream and downstream methods are employed to
optimize the disposal scheme.
fig: centreline raising of ash dykes.
iv)Offset Raising
This method can be used when the existing embankment is extremely weak to
support the loading caused by raised embankment.
This method has the same issues as the down-stream raising, but are to be
more seriously dealt, since apart from the starter dyke being weak, the offset
has to rest on the slurry. Hence, the attainment of stability in terms of slope
and bearing failure is under serious question. As such, this method is only used
to tackle extremely unprecedented situations.
fig: offset raising of ash dykes.
As can be comprehended from the above discussions, various raising
techniques pose different types of challenges in the construction and to
maintain the integrity and safety of ash dykes. The threat to safety is mainly
dealt in terms of the slope failures of the dykes and bearing failure of the
bases.
71
3.7 CONCLUSIONS
The report provides a comprehensive overview of the layout and possible
construction methodologies of ash dykes. Various case studies cited herein
reveals the different forms of challenges which can be possibly depending
upon the specific requirements of the generated problem. Necessity of various
ground improvement techniques is exemplified. It is to be understood that
ground improvement does not necessarily mean inclusion of artificial
reinforcing materials within the soil, which seems to be slowly grasping the
present day notion. Even a simple dewatering technique aids in the ground
improvement. The above study reports the usage of several basic and common
technique of ground improvement which can be successively used to improve
the bearing properties of the soil or prevent a soil mass from stability failure.
The case studies techniques such as simple flattening of slopes to reduce the
shear stress, dewatering and drainage to reduce the seepage conditions and
exit gradient, application of vertical drains for accelerated consolidation and
improved bearing characteristics, usage of gabion walls for toe hill protection
against failure and excess stress, use of weirs under special cases to tackle
terrain runoff, and glimpse of application of geofabrics to enhance the slope
stability. This should help to open up the scopes of various simple techniques
that can be used in case of necessity to stabilize an ash dyke. The industries
need to come forth to accept such challenging innovations apart from just
flattening of slopes, which is a common and successful age-old practice.
supervised &mentored by
…………………………………………
Mr. P.K. Singh
(MANAGER,CIVIL DEPTT.,jspl)
72
chapter 4-
During the course of our internship, we were exposed to other civil engineering sites except those mentioned like blast furnace and its capacity increase, road construction near cement factory, back filing of stock home and other sites. these experiences have been summarised under this chapter.
chapter 4(i)
In construction a backfill is material used to refill an excavated area. Rather than be discarded this material is often utilised for some task like for protecting foundations, landscaping or filling of voids. Back filling can also be put around a fresh foundation wall to give it more stable environment.
Backfill is a natural material that is used to fill the void left after construction or sometimes excavation efforts. it is a combination of a of stone, soil and other materials that were left over after the main portion of the project was completed.
In most of the back filling jobs at JSPL plant,slag was used as the back fill
instead of conventional soil ,because of its huge availibilty
At stock home near the blast furnace, back filling of an area with conveyer belt
and hoppers is in progress.
Back fill or backfilling, is aggregate that is removed from a building site as part of the construction process. Rather than simply being carted away and discarded, this aggregate is often used for some purpose that is not only practical, but also environmentally friendly. It can be used in tasks such as
Industrial tour & other civil engineering sites
Back filling of stock home near BF 2
73
protecting foundations, landscaping, or filling in voids that would weaken underground structures.
(back filling of a site in progress here soil is a natural choice to be used as backfill material.) Perhaps one of the most common uses of this material is to provide some protection along the base of a foundation wall. After the excavation of the building site is completed, the foundation is put into place. In order to provide the foundation wall with more support, the excavated dirt is firmly packed around the perimeter of the foundation. This effectively helps to minimize shifting and provide a more stable environment for the structure that is erected on the foundation. A second application for backfilling is found with mining operations. When various types of ores are removed from the ground, there is a void left where the harvested veins once resided. In order to maintain the integrity of the mine and make it possible to continue expanding the underground mining operation, aggregate is used to fill those voids. This will minimize the chances of one or more chambers in the mineshaft from collapsing as the mining procedure continues. Backfilling can also be put to good use when landscaping around a home, a new commercial building, or even when changing the lay of the land in preparation for a new section of road or highway. With this application, the material is brought in from another location and used to fill in or build up sections of the terrain. The aggregate makes it possible to even the ground
74
surface so that the area around a newly constructed home can be landscaped with trees and various types of flora and fauna.
At the same time, the backfill can be hauled in to a relatively flat area and used to build up inclines that are necessary for the construction of the overpasses that are common on many highway systems. By packing the material tightly, the elevated sections easily accommodate the construction of a connecting bridge that allows an overpass to be erected over a bisecting road or street, effectively allowing the flow of traffic to proceed in a more efficient manner.
Backfill is also used to surround pipes that are buried beneath the surface. With this application, the filling helps to protect the pipe from damage, a function that is particularly important when the pipe carries electrical wiring or natural gas. The natural buffer of earth helps to absorb vibrations from the surface that would otherwise weaken the pipes over time, causing interruptions in utility service or creating health hazards for anyone living in the area.
(back filling of a foundation)
75
chapter 4(ii)-
jindal Steel & Power has successfully commissioned the 351 cubic metre (m3)
blast furnace at Raigarh district of Chhattisgarh within 16 months from zero
date.
The design of the blast furnace was based on the latest technology and is fitted
with stave cooling, cast house, hot blast stoves, gas cleaning system, blowers,
slag granulation unit, conveyorised charging system, stock house with
electronic weighing system and all other service facilities. The blast furnace has
also been provided with PLC-based control & monitoring system for furnace
charging and hot blast stoves. The advanced features would help in high
productivity and less energy consumption.
Mecon was the project management consultant for the blast furnace.
Blast furnace site:increasing its capacity
76
4(ii).1 BLAST FURNACE DESIGN PHILOSOPHY
Building or renovating a Blast Furnace plant requires considerable capital
expenditure, having obvious consequences for the owner’s cost per ton of hot
metal. However, many of the performance indicators of the Blast Furnace ,
such as availability, lifetime and the ability to operate on a wide variety of raw
materials, translate into value eventually reducing hot metal cost.
The furnace’s internal dimensions and profile determine its maximum annual
production, given the availability of raw materials and maximum levels of coal
injection and hence oxygen enrichment.
In general, the lining design is focused the formation of a solidified layer of slag
and burden materials that will reduce the effects of these attack mechanisms
considerably. In addition, a number of areas that are critical for achieving the
goal of maximized value of the furnace are identified.
77
THROAT ARMOR
Failure of the throat armor has a significant detrimental effect on burden
distribution on the stockline and directly below. Irregular burden descent and
compromised process stability are known consequences. The throat armor
design should be optimized with respect to resistance to spalling,temperature
fluctuation, stresscracking, fatigue and abrasion/erosion.
BOSH, BELLY AND STACK
The bosh area is severely loaded by the descending burden it carries and the
raceway gases in its vicinity. The belly and stack are exposed to heat loads and
severe abrasion. In some cases, the cooling body and lining wear down to
critical levels far too soon after blow in, including a risk of breakouts. In the
bosh area, it also means that the burden is carried by the tuyere noses and
jumbo coolers, causing highly frequent unprepared stops. The Danieli Corus
bosh and stack design, consisting of copper plate coolers and high conductivity
graphite along with protective silicon carbide in the upper areas, transfers 95%
of the heat load onto cooling water, securing that the shaell temperature
remains under 50 degree celcius. It is expected to achieve endless campaigns,
given conditions found in furnaces after over 20 years in peration.
HEARTH
Given the long life of furnace’s bosh and stack, campaign lenth is now dictated
by hearth life. Liquid flows introduce considerable wear through mechanisms
such as erosion and carbon dissolution. Also, structural integrity of the hearth
is likely to be compromised since e.g. expansion during heat-up can cause
displacement. Through field obseravations able to improve hearth design to its
current level, allowing for hearth campaigns between 15 and 20 years.
TAPHOLE
The Taphole is exposed to an extremely dynamic environment. Not only are
temperature and pressures high, chemical attack is substantial and frequent
drilling and plugging of the taphole make circumstances even more
complicated.
At some furnace, sufficient hot metal for the production of up to 20,000
78
average passenger cars is removed through relatively small diameter holes
every single day. Designing the ultimate taphole, capable of facilitating this
operation for periods up to 15 years, is one of the most demanding challenges
imposed upon plant builders.
Today, optimum results can be achieved with superior cooling of the shell
around the taphole, a reductant lining design and sufficient monitoring
capability.
REACTIONS IN BLAST FURNACE
At the temperature of 900-1600°C, a reduction with carbon occurs:
1.
2.
3.
Now iron has been made. 4(ii).2 DIAGRAM OF BLAST FURNACE
79
1.Hot blast from cowper stoves 2.Melting zone 3.Reduction zone of ferrous oxide 4.Reduction zone of ferric oxide 5.Pre-heating zone 6.Feed of ore, limestone, and coke 7.Exhaust gases 8.Column of ore, coke and limestone 9.Removal of slag 10.Tapping of molten pig iron 11.Collection of waste gases
80
4(ii).3 Conclusion
Expansion of Blast Furnace is necessary to yield smelting of industrial
metals particularly iron.
During the process the furnace is keep off power to skip any mishap.
RCC slabs are necessary to accommodate extra pillars for hooper
conveyer belts and columns.
Backfilling is necessary of low lying area in stock home to keep it
levelled with land outside the retaining walls.
In most of the back filling jobs at JSPL plant, slag was used as the
back fill instead of conventional soil, because of its huge availability.
Supervised and mentored by
………………………………………..
Mr. Arun Kumar Arya
(Manager,civil deptt,jspl)