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CIVIL ENGINEER’S
HAND BOOKFOR
CONSTRUCTION SUPERVISION
S.K.GUMASTA
RAJASTHAN ATOMIC POWER PROJECT – 5&6
UNVEILED BY PROJECT DIRECTOR, RAPP-5&6
ON 11.02.05 AT RAPP-5&6 SITE.
PREFACE In order to sustain within competitive environment, stress is
given to reduce the gestation period with maintaining the
quality standards of Construction & Commissioning of
Nuclear Power Programme. This is up most important to
reduce the construction time and cost of nuclear power
considering the above aspects. For reduction in cost of
construction few of the requirements are listed as below: -
1. Optimum use of skilled manpower.
2. Mechanization in construction.
3. Awareness of quality system to all supervisors / Engineers.
4. Create competitiveness within working group.
5. Continuous training and performance appraisal of
Supervisor / Engineers.
Construction is major part of Civil Engineering which
includes awareness regarding the Quality Control, Material
Selection, Storage & Handling, Mix Design, Managerial skill to
handle the situations in Pre Construction, During
Construction and Post Construction stages. Effective and
desired results with optimum use of departmental manpower
engaged in Supervision of Construction activities is always a
major concern of NPCIL vision and policy.
Based on daily observation & experience that have been
gathered during handling of various site execution activities,
a need was felt to have a document containing brief
description of the work and effort required for various stages
of construction for improvement of effective supervision of
construction.
This document has been prepared as handy tool for ready
reference of Site Civil Engineers and Supervisors. It contains
information basically for site related activities/ checklist
being used on day-to-day basis.
Special emphasis have been given on the skill requires for
supervision of the Civil Construction activities for Site
Engineers/ Site Supervisor to handle the situation w.r.t. Pre-
Construction, During Construction & Post Construction
responsibilities.
Following are the areas enlisted in this document: -
How to organize the job for effective and desired out put
at site.
Importance of Survey in Civil Construction.
Excavation and blasting techniques.
Requirement for formwork placement.
Re steel fabrication and placement.
Importance of Concrete cover.
Pour planning.
Pour checks.
Brief description regarding concrete and mix design
development.
Requirement for concrete production transportation and
placement.
Post-concrete inspection.
Various types of finishes in concrete.
Defects in concrete and its repair.
Various types of joints.
Assessment of safe working conditions while executing the
job.
Importance of Job hazard analysis.
Awareness of QA requirements.
I am thankful to all my colleagues and senior Civil Engineers,
who have shared their valuable experience which had paved
the way for making this possible.
I would like to extend sincere thanks to Sh. J.K.Jain,
Sh. S.K.Shrivastava, Sh. H.P.Choudhary & Sh. V.K.Trivedi for
their personal support. The inspiring support and
encouragement provided by Sh. N.K.Jain, ACE (E&I) and
Sh. Sanjiv Sharma, PE (C) is also thankfully acknowledged.
The development of this document as reference to the
requirements of Site Supervisors and Site Engineers, who are
directly connected with work was the vision of Sh. D.K.Jain,
Chief Engineer (Civil). This could be made possible due to his
able leadership, and effective guidance, continuous
motivation and appreciation at every stage for development
of this document in presentable form. I am also grateful to
Sh. C.P.Jhamb, Project Director, RAPP-5&6 for giving
Enthusiastic and inspiring support for development of this
document.
S.K. GUMASTA RAPP-5&6
INDEX
SR.
NO. DESCRIPTION
1 How to organize the job for effective and desired out put at site. 2 Importance and requirement of survey.
3 Excavation and blasting techniques.
4 Requirement for formwork placement.
5 Re steel fabrication and placement.
6 Importance of Concrete cover.
7 Pour Planning.
8 Pour Checking.
9 Brief descriptions regarding concrete and mix design development.
10 Requirement for concrete production transportation and placement.
11 Post-concrete inspection.
12 Various types of finishes in concrete.
13 Defects in concrete and its repair.
14 Various types of joints.
15 Assessment of safe working conditions while executing the job.
16 Importance of Job hazard analysis.
17 Awareness of QA requirements.
CHAPTER - 1
HOW TO ORGANIZE THE JOB FOR EFFECTIVE AND DESIRED
OUT PUT AT SITE
CHAPTER - 1 How to organize the job for
effective and desired out put at site
Learning is a continuous process for individual improvement & is important and essential for completion of jobs with required quality standard and maintaining the time schedule for achieving the targets. Optimum use of availability of skilled manpower is always a matter of concern to all of us in a present competitive world. Further it is needless to say that “ABILITY IS USELESS UNLESS IT IS USED” Hence it is a big challenge for us that “How to organize the job for effective and desired out put at site”.
Following are the few points, which shall be helpful to achieve the above
objectives: -
1) Develop confidence within our self and our team for having
capability to deliver the task.
2) Understand the work in totality before actually proceeding it.
3) Identify the requirement of material, equipments, availability of
drawings / specification, qualified manpower and their availability.
4) Identify the possible hindrances, constraints well in advance and
proactive approach to arrange the solution.
5) Prior requirement i.e. proper pour planning and checking before
execution.
6) Identification of Pre construction / During construction /Post
construction requirement of various sub activities.
7) Proper access to site, good illumination, logical and proactive
approach and quality consciousness.
8) Understanding of job and analysis of job hazards prior to start of
the work.
9) Always believe “Ability Has Nothing To Do With Opportunity”
hence deliver the results rather than discussing the excuses.
10) Communication to immediate superior for appraisal of work done.
Such appraisal is appreciated, if it is done before it is asked for.
Remembers - One should not require any reminder for complying
the instruction of superiors.
11) Practice to be a good leader and not the boss for effective team
sprit and desired output.
12) Motivate the team and set an inspiring example for others.
13) Always believe that ”Sincerity has no substitute”.
CHAPTER - 2
IMPORTANCE AND REQUIREMENT OF SURVEY
CHAPTER - 2
IMPORTANCE AND REQUIREMENT OF SURVEY
Survey plays an important role in Construction activities. It is basic requirement
to ensure the correct location and alignment including required elevation slop etc
for structure or total layout of a plant. Survey is done for the maintaining above
requirement. Brief of survey terms used is indicated below: -
SURVEYING: - Surveying is the art of making such measurements as will
determine the relative positions of points on the surface of
the earth or on structure in order that the shape and extent
of any portions of the earth/structure may be ascertained
and shown on the map or plan.
LEVELING: - Leveling is the art of determining and representing the
relative heights or elevations of different points on the
surface of the earth/structure.
1 SEQUENCE TO BE FOLLOWED FOR SURVEY W.R.T. START OF THE
WORK: -
Following are the salient points/ sequence of survey to be followed for
start of the project activates/ pour: -
WORK IS DIVIDED IN TWO PARTS.
A. To start a new project: - Establishing of Main grid lines and Benchmark
with reference to known datum / reference to start in new work.
B. For a pour in existing structure: - Use of existing reference/bench mark
in existing structure to define the location, alignment and elevation of a
pour.
2 USE OF SURVEY IN VARIOUS DAY-TO-DAY ACTIVITIES OF
CONSTRUCTION.
Before we deal with uses of survey for various activities, following steps
are necessary to carryout.
A. Transfer of reference line at each Building/floor to carryout checking of
various activities.
B. Transferring of Bench Mark at each Building/floor.
C. Above two activities should be performed with great care and without
any error, as the effectiveness of total checking depends on theses
reference points.
D. Establishing layout of the building.
E. Establishing bench mark to check elevations of different floor etc.
F. Use for checking of form works: -
i) Alignment checking
ii) Checking of verticality.
G. Tolerance for formwork
i) Section dimension - ± 5 mm
ii) Plumb/ verticality - 5mm in 5 mtr. But should not cumulative.
H. Use in checking of critical EPs.
Checking of location
Checking of elevation
Tolerance –
Before concreting ± 2 mm.
After concreting ± 6mm.
Tolerance on angle± 0.500.
Survey is very important at pre-construction, during
construction and post construction stages. Site Engineers must
be aware regarding requirement and importance of survey at
pre-construction, during construction and post construction
stages. Few of the requirements are summarized below: -
3 Pre construction survey is required for the following: -
i. Defining the plant area in 20m X 20m plant grid pattern with
existing permanent reference.
ii. Location of various plant structures within defined grid established
as above.
iii. Making specific benchmark to take up the work within building /
structure.
iv. Marking and identification of a part of the structure in various
pours at various elevation w.r.t defined Benchmark / reference.
v. These marking are possible by: -
Theodolite.
Measuring tapes.
Dumpy level.
Total station.
vi. At the start of construction- usually reference point is marked on
reference pillars 2-3 meters away from the edge of structure.
vii. After construction, it is transferred to permanent structure and
subsequently all reference to be taken from common reference to
avoid any cumulative error.
4 During construction is required for the following: -
i. During construction survey is very important. Following are the
areas where survey during construction requires by supervisor /
site engineers.
ii. Maintaining alignment of wall and position of embedded part, pipe
support/ piping sleeves etc.
iii. Maintaining the location of EP’s / specifically critical EP’s.
iv. Maintaining the concrete top elevation of plate EP’s / Critical EP’s.
v. Maintaining the concrete top elevation during finishing of green
cutting.
vi. Maintaining the slopes of floors.
vii. Maintaining the levels of sumps.
viii. During concreting survey is made to ensure the location of PVC
water stop.
5 Post concrete survey: -
i. Post concrete survey is done for all critical pours to ensure the final
position of EP’s / Levels of concrete.
ii. It is required to done to assess the tolerance in alignment / level
/pockets / bolts etc. in concrete structure.
iii. Post concrete survey is done to examine the spot of honey combed
portion / visual observation of bulging and type of surface finish in
concrete.
CHAPTER - 3
EXCAVATION AND BLASTING TECHNIQUES
CHAPTER - 3 EXCAVATION AND BLASTING
TECHNIQUES
At NPCIL, Rajasthan Site, we face the greatest challenge of getting the
excavation done at hard rock available here.
Excavation at this site is a critical activity since blasting is the only
economic solution available for excavation in hard rock here.
Following is the salient point generally we refer before proceed for the
work.
1. PLANNING OF WORK. – In order to asses the requirement of
various machineries / explosives required to complete the blasting work
with in schedule time considering hindrances / constraints etc., planning
of the work including resource planning is very important for site
engineers before starting the job. A brief for activities required for
planning of the work is summarized below.
Sr.
no. Description Desired output
i. Total quantity of excavation to be done In Cu.m.
ii. Total time available. No. of Days.
iii. Target excavation to be done per day. Total Qty/No. of days.
iv. Increase target excavation by 15% to
20% due to uncontrolled conditions like
break down of machineries/non
availability of explosive materials /
restriction in blasting due to nearness of
on going works / critical structure.
(Assuming blasting is permitted once in a
day)
Row no. iii X 1.5 cu.m /
per day.
2 RESOURCE PLANNING
i. Considering capacity of a poclain to handle
excavated muck/day and using target
excavation/day, we can calculate - No. of
required poclain.
No. of required
poclain can be
calculated based on
this data.
ii. Considering the capacity of dumpers to
handle the excavated muck to disposal
yard / day and using the target excavation
rate per day, we can calculate - No. of
required dumpers.
No. of required
dumpers per day can
be calculate based on
this data.
iii. Based on the experience at this site
approx. depth of borehole in RM required
to achieve one Cu.m. of excavation and
the total excavation is to be done, we can
calculate total RM of drilling required.
(Approximate assumption as 0.8 to 1.0 RM
drilling as an average to achieve one Cum
excavation at this site may be assumed
for planning purpose. This data may
vary for various types of work and their
location.)
This will help to
calculate total Drilling
required in RM.
iv. Considering the capacity of borehole drill
machine to drill-RM/day and using the
target excavation rate per day, we can
calculate total no. of borehole drilling
machine requirement. (Approx. 70 to 80
RM drilling is done per day by a borehole
drill machine can be safely assumed for
planning purpose)
No. of borehole
drilling machine
required can be
calculate with this
data.
v. Considering the capacity of jackhammer
capability to drill RM/day and using the
target excavation rate per day, we can
No. of jack hammer
required can be
calculated with this
calculate total no. of jackhammers
requirement. (Approx. 50 to 80 RM
drilling per shift can be safely assumed for
planning purpose)
data.
vi. Based on the experience at this site
amount of explosive required in Kg to
achieve one Cu.m. of excavation and the
total excavation is to be done, we can
calculate total explosive requirement.
(Approx. 0.5 to 0.7 Kg explosive
requirement can be assumed to achieve
one Cum excavation at this site for
planning purpose.)
This will help up to
calculate total
quantity of explosive
required in kgs. This
will help us to assess
the requirement of
storage of explosive /
magazine.
3 BLASTING & BLASTING TECHNIQUES: - A. BLASTING:- The fragmentation of rock by means of explosives is
called ‘blasting’. There are two type of explosion: -
I. Deflagration: - Explosion by rapid burning
II. Detonation: - Explosion by instantaneous decomposition
B. MUFFLED
BLASTING
Muffled blasting refers – blasting with control of fly
rock. It is defined as preventive action for flying stones
by covering blasting area by steel plates / sand bags
etc.
Control of fly rock: - Blast hole shall be covered with 6
mm thick (min) MS plate 0.6 to 1.0 sq.m – scrap steel
plates/ sand full of gunny bags are used during muffled
blasting for covering the area.
C. CONTROL
BLASTING
In control blasting muffling is not only the requirement
but also controlling the generation of peak particle
velocity due to vibration in nearby Civil structure/
critical and sensitive installation without affecting their
performance of structures is main concern for control
blasting.
Control of vibrations- Short delay blasting with light
charges: - Rapid sequence of shot firing with delay of
25 -100-mili seconds.
D. LIMITED
BLASTING: -
To safeguard existing structures and nearby operating
station, permissible PPV is defined as below: -
1. Peak particle velocity 10 mm/sec for near by civil
structures.
2. Peak particle velocity 3 mm/sec. –Safe vibration
level for buildings.
??With electric & electronic equipment installed at
basements.
??Safe charges per delay have also been
specified by CWPRS for various distances and
age of the concrete.
E. LINE DRILLING: - ??By drilling a series of hole at closely spaced
intervals around the perimeter of the excavation
the blast may be trimmed to the finished
dimensions with a minimum over break.
F. PRE-SHEARING: - ??Is a development of line drilling method by
instantaneously firing a closely spaced series of
holes, lightly charged around the desired
perimeter before the nearby main rounds are
blasted.
??Firing of light charges produces tension cracks.
??These cracks de-couple the main blast from the
perimeter rock walls, which are thereby left
intact and unbroken.
??Dia of holes –110 mm Ø
??Spacing –800 to 1000 mm c/c
??Charged –300 to 400 gm /m
G. EXPLOSIVES: - Explosives are chemical compounds. They decompose
quickly and violently and change into gases. Such
gases have larger volume. The heat generated serves
to expand gases greatly.
EXPLOSIVES
LOW EXPLOSIVES HIGH EXPLOSIVES
(Deflagrates) (Detonates)
H. LOW EXPOLOSIVES:
-
‘Gunpowder’ is the example of ‘low explosives”
Features of ‘Gun Powder’
i. Gun powder 75% Potassium Nitrate - oxygen supplier
ii.Composition: - 15% charcoal powder - inflammable
10% sulphar.
iii.
Rate of burning; - The speed of burning of gunpowder is of all order of
450 m/sec. The volume of gases produced is as large
as 2000 times the volume of gunpowder used.
iv.
Other properties:- ??Made to explode by ‘Safety fuse’
??Because of its low strength, it is not used in large
scale blasting.
??Can easily absorb moisture.
??Its transport is risky – being inflammable.
??While Stemming –explosion may take place needs
proper care during handling.
I. HIGH
EXPOLOSIVES: -
Open cast gelignite, special gelatin, blasting gelatin
super dyne is examples of ‘high explosives’.
i. Main constituents: -
1) TNT (Tri-Nitro –Toluene)
2) Nitro-glycerin
3) Ammonium Nitrate
4) Collodion cotton
ii. Features: -
??Should not be exploded by ignition
??Detonators create ‘shock waves’ of velocity
ranges from 2000 m/sec to 7000-m/ sec.
depending upon quality, nature and strength of
explosive used.
??The mechanical energy of the shock waves does
the work of fragmentation of work.
J. Safety Fuse: - 1. Safety fuse consists of core of fine gunpowder
wrapped with layers of tape, jute and is given
a coat of ‘water proofing’.
2. It will burn without the help of oxygen, inside
water and inside the blast hole.
3. Rate of burning = 2 feet /minutes.
4. Some brand names “Bull brand” “Blue sump”
and “Colite fuse”.
5. High explosives can be detonated with the
help of safety fuse, provided it is capped with
an ordinary detonator.
How to determine
length of a fuse: -
??The blaster should take into consideration the time he
will need to light the fuses and to reach the shelter
safely shall determine the length of a safety fuse.
??Suppose time for lighting 10 fuses requires = 2 min.
??Time to reach the shelter = 5 min. ------- Total time = 07 min So he will need to have 14 feet fuse since the rate of
burning of fuse is 2 ft/min.
K DELAY Delays are used to have small time gap between
successive blasting to avoid strong vibration generation
at a time.
At our site as specified in tender document delay per Kg
of blast to be used w.r.t. distance of sensitive or
permanent installation while blasting
L STEMMING: - Too little stemming results - Allow explosion gases to
vent out and fly rock problem.
Too much stemming results - Poor fragmentation.
M ORDINARY ELECTRIC
AND DELAY
DETONATORS
??These are initiated by pressing an electric current
with an apparatus called “EXPLODER”.
??When electric current of about 0.5 amp is passed
the fused head get heated ignite primary charge
which in turn will initiate IInd charge and the
detonation takes place.
The difference between ordinary electric
detonator and delay detonator is due to of
insertion of a “delay element, which has property
of burning at specific rates.
The heart of a detonator is “fuse head “.
Any mal-functioning of this will lead to misfire.
N INITIATION
SEQUENCE OF
DETONATION OF
EXPLOSIVES
To be strictly followed for effective results.
O USING DELAYS: - When the explosive charges in two or more rows of
holes parallel to a face are fired at the same time it is
desirable to fire the charges in the holes nearest the nd
face a short time ahead of those in IInd row. This will
reduce the burden on the holes in IInd row and thereby
permit the explosive in IInd row to break the row more
effectively.
The use of delays in the blast is one of the most
powerful weapons in the fight against excessive blast
damage and larger peak particle velocity and in-turn
instability of surrounding area.
MISFIRES: - While shooting explosives charges by blasting, it may be
possible that one or more charges will fail to explode.
This is referred to a misfire. It is necessary to dispose of
this explosive before excavating loosened rock.
P
HOW TO HANDLE
MISFIRES: -
??The most satisfactory method is to shoot it, if
possible.
??If electrical detonator is used, leg wires are available
and circuit is satisfactory, try again to set of charge.
??Stemming should be removed with a wooden tool
instead of metal.
??Water and compressed air should be used to remove
stemming.
??A new charge on top of missed one may also be
blasted to fire the charge.
4. ECONOMICS OF BLASTING
i. To achieve
optimum results:
Following parameters are required to be taken into
consideration –
1) Type of explosive, weight of explosive and
distribution of explosive in holes.
2) Blast hole diameter – If large – flying of rock in air
will be less but secondary blasting may be required to
will be less but secondary blasting may be required to
handle large boulders generated.
3) Effective burden: - The distance between the row of
holes under consideration and the nearest free face is
know as effective burden.
If burden is small - Generation of fly rock in -air and
lesser efficiency of blasting will be resulted.
If burden is too large - Check the blast due to -Poor
fragmentation.
ii. Effective spacing: - For good results – effective spacing of holes = 1.25 x
effective burden.
iii. Sub drill depth: - To avoid excessive shovel operation at floor level depth
of hole is kept little less than required.
5 MONITORING OF ACTUAL PROGRESS AGAINST PLANNED PROGRESS
OF BLASTING: -
1) Compare for no. of holes blasted against no. of holes planned to blast
per week.
2) Target excavation rate against achieved excavation rate per week / per
month.
3) Reorganize the deployed resources in case large variations are noticed.
6 REQUIREMENT OF THE PRE BLASTING ACTIVITY: - i. Proper resource planning w.r.t requirement of machineries / availability of
explosives / requirement of storage of explosives/ availability of qualified and
licensed blaster to be ensured.
ii. Blasting notice to all concern and near by all agencies working in the area
/CISF/safety group and to nearby working stations must be circulated. Blasting
notice must indicate blasting timings for specific duration for which it is issued.
iii. Daily blasting permits indicating no. of holes/app. Blast charge requires /
departmental representative to attend / witness the blasting to be taken
iv. This daily permit needs clearance from department safety head and the CISF
authorities well in advance preferable one day in advance
v. Drilling of required no. of holes of desired dia and inclination to be ensured in
one day advance
vi. Availability of muffling plates / sand bags to be ensured at site in one day in
advance
vii. Availability of PPV meter at site for monitoring the vibration to be ensured at
site.
7 REQUIREMENT OF DURING BLASTINGS ACTIVITY: -
i. Loading of required explosive in blast holes to be ensured by licensed blaster
only.
ii. Connecting the blast charge with desired delays in specific circuits to be
ensured by licensed blaster only.
iii. Ensuring the cordon-off the area for entry of vehicle / explosive / Labour.
Using whistle / red flag / siren.
iv. Blasting to be done and measurement of PPV should be recorded.
8 REQUIREMENT OF AFTER BLASTING ACTIVITY: -
i. Blaster must checks for misfire if any and accordingly arrange for reblast if
necessary as per procedure.
ii. Give clearance if no misfire noticed for entry of vehicles / movement of
workers etc..
iii. Check for any damage occurred in near by area. It is requires to be reported
in the blasting report, if any.
iv. Generation of blasting reports including statement of reconciliation for the
explosive materials brought to site, consumed at site and balance taken away
from the premises of the project in presence of CISF.
v. Compare the PPV observed against permissible Peak Particle Velocity for the
area.
9 Following details also must be known for effective monitoring of
blasting operation.
BLASTING AREAS: -
Blasting areas where concreting is being done i.e. w.r.t. green age of the
concrete. This data is obtained from the conclusion drawn by CWPRS at site in
their survey.
In nutshell it refer that blasting in the nearby area where green age of the
concrete is 0-4 hrs. is not harmful. But for the concrete having age between 4-
12 hrs. - No Blasting to be permitted in near by area.
CHAPTER – 4
FORM WORK PLACEMENT
CHAPTER - 4 FORM WORK PLACEMENT
1. Formwork is defined as total system of support of fresh
concrete to be placed it includes: -
??Total frame / mould of various shape in which concrete remain
in contact.
??Total system of supporting arrangement i.e. by frame, pipes,
acro-span, trusses etc.
??Nuts, bolts tie rods, bracing including other supporting system
for satisfactory sustaining the load of concrete + live loads
until the concrete attain the strength to with stand the same.
2. Various type of formwork are used in construction: -
a) CONVENTIONAL FORMWORK: - Includes – formwork i.e.
shuttering made up by steel plates and industrial plywood includes
pipe support’s / wooden ball support.
b) DOCA FORM WORK: - Specially designed form work with simple
methods for fixing in position and removing from the position. This
tread name of formwork had proved confidence in various
complicated structure for their satisfactory completion. This can be
used for large slabs, big columns, deep beams, large size retaining
walls, and hyperbolic cooling towers etc.
c) SLIP FORM WORK: - In structure where shapes are regular of
having a uniform variation like shaft of water tank, chimney,
towers etc. and not having penetrations. This type of form work
can effectively used for rapid construction in this case form work is
design in such a way that it moves continuously ahead to receive
the fresh concrete in such a way that when it leaves the concrete
already placed should attain the sufficient strength to withstand
the load of concrete + live load, while concreting is done. In this
case concreting is done continuously till the work is over for the
shape
Example: - Shaft of water tank for 15-20 Mtr. can be completed in
4 to 5 days.
d) JUMP FORM; - Where Shape / Geometry of the structure is not
uniform and height of the structure is more. Jump formwork can
be used. For example about 100 to 110 m high and 90m to 55 m
dia of cooling tower shell varying hyperbolically being constructed
with the jump form at RAPP-5&6 site.
3. Site Engineer / Supervisor must give attention to following
areas while checking the formwork / scaffolding.
PRE CONSTRUCTION REQUIREMENT: -
Alignment level position of formwork w.r.t permanent
reinforcement.
??Type of finish requirement decides the type of formwork.
??Spacing of the support system Tightening of bolt, tie rods
etc.
??Accuracy of dimensions.
??Gap in the successive shutters to avoid the slurry leakage.
??Where penetration / EP’s are to be made, the supports are
to be re-ensured to maintain dimension, alignment and
level of the same.
??Bracing and adequate support for projections/ cantilever
must be checked.
??Wherever construction joints are to be left, the position of
shear keys, and support arrangement to be ensured.
??Safety aspects to be taken care while checking the
formwork the proper access to reach other portion of form
work to be ensure, an case needs attention during the
concreting.
??Form fixing to be checked w.r.t removal of form work point
of view. It should be easily removable without damaging the
final concrete.
REQUIREMENT DURING CONSTRUCTION
??A set of skilled carpenter to be ensured to attend the area
immediately in case, support’s / forms gets displaced while
concreting / vibration of concrete.
??Proper illumination in internal and external location of pours
to be ensured.
??Application of surface retarder immediately before the
concreting where green cutting is required.
POST CONSTRUCTION REQUIREMENT: - In general the codal
practice for removing the formwork to be strictly followed for
removal of form.
??For special structures like dome of reactor and shell of
Cooling Towers: -Specified procedure to be followed for
removal of form.
??Specific care to be observed for safety during disturbing.
??Specific care to be observed while removing formwork at
high structure should not damage the structure at floor.
Removal of the formwork at various constructions needs
attention as summarized below
Forms should not be removed until the concrete has achieved strength
that is at least twice the stress to which the concrete may be subjected
at the time of removal of formwork. However, under normal
circumstances, where no significant variation temperature is seen the
following striking period should be followed: -
Removal of forms and supports (As per IS456-2000)
Sr. no.
Position of formwork Min. period before striking formwork.
1. Vertical formwork to columns, walls, beams.
16-24 hours.
2. Soffit formwork to slabs (props left under after removal of formwork)
3 days.
3. Soffit formwork of beams (props left under after removal of formwork)
7 days.
4. Props of slabs (spanning up to 4.5 m) 7 days. 5. Props to slabs (span over 4.5 m) 14 days. 6. Props to beams & arches (spanning up to
6) 14 days.
7. Props to beams & arches (spanning over 6m)
21 days. ??Striking should be done slowly to avoid damage to projections and
without shocks or vibration.
??When forms are stripped, there should be no excessive deflection
or distortion and no evidence of damage to the concrete due to
removal of support.
??When forms are removed before the specified curing is
completed, curing should be continued up to the specified time.
??The concrete supporting forms and shores not be removed from
beams, floors and walls until these structural units are strong
enough to carry their own weight or any approved superimposed
load. In no case should supporting forms and shores be removed
from horizontal members before concrete strength has achieved
this specific concrete strength.
??It is always recommended to remove forms for columns and piers
before forms for beams and slabs.
CHAPTER - 5
RE-STEEL FABRICATION & PLACEMENT
CHAPTER - 5
RE-STEEL FABRICATION & PLACEMENT
Steel reinforcement is a major and most important constituent of
concrete. The correct shape and its position and cutting length is the
main area required to be seen by Site Engineer. Silent feature for
Fabrication & Placement of concrete reinforcement is briefly described
below.
TYPE OF REINFORCEMENT: - 1) High strength deformed bars – (Conforming to IS: 1786)
(a) Cold worked deformed bars.
(b) TMT bars
2) Mild Steel Bars – (Conforming to IS: 432)
3) (A) MATERIAL PROPERTIES FOR HSDB i. CHEMICAL PROPERTIES
Constituents Fe415 Fe500 Fe550 Carbon 0.30 0.30 0.30 Sulphur 0.060 0.055 0.055 Phosphorus 0.060 0.055 0.050 Sulphur & Phosphorus 0.11 0.105 0.10 For weldebility % of C > 0.25
ii. PHYSICAL PROPERTIES Mechanical properties of high strength deformed bars:
S. No.
Property Fe415 Fe500 Fe550
0.2% proof stress
415
500
550
% Elongation on gauge with 5.65 A
14.5
12.0
8.0
Tensile Strength
10% more than actual 0.2% proof stress or not less than 485 N/mm2
8% more than actual 0.2% proof stress or not less than 554 N/mm2.
6% more than actual 0.2% proof stress or not less than 585 N/mm2.
3 (B) MATERIAL PROPERTIES FOR MILD STEEL: - i) CHEMICAL PROPERTIES Constituents Upto 20 mm Above 20 mm
Carbon 0.23 0.25 Sulphur 0.055 0.055
Phosphorus 0.055 0.055 ii) PHYSICAL PROPERTIES MECHANICAL PROPERTIES OF MS BARS: - S. No.
Property Grade-1 (less than 20 mm)
Grade-1 (Above 20 mm)
0.2% proof stress 250 240 % Elongation on gauge
with 5.65 A 23% 23%
Tensile Strength 410 mpa 410 mpa
Material Sampling and Acceptance to be ensured as per requirement.
(4) CUTTING & BENDING OF RE-STEEL BARS: -
Cutting & Bending shall be done in accordance of requirements laid
down in IS: 2502 as per the Bar Bending schedule. The
reinforcement bars shall be cold bended. Fabricated bars should be
tagged indicating the following information: -
(a) BBS (b) Structure (c) Bar mark (d) No. of Bars.
(5) PLACEMENT OF BARS: -
Placement of re-steel bars shall be done as per arrangement shown
in approved reinforcement drawings.
(6) Reinforcement work shall be checked for the following: -
FABRICATION: -
(i) Diameter of the bar
(ii) Shape of the bar
(iii) Finished length of the bar
(iv) Bending radius
(v) Visual inspection for crack during fabrication
LAYING
(i) Location
(ii) Alignment and array
(iii) Spacing / numbers
(iv) Binding / tying
(v) Cover
(vi) Staggering if any
(vii) Splicing – numbers and location
Inspection status shall be mentioned in the form of Pour Card.
(7) PLACING OF REINFORCEMENT
Rough handling, shock loading prior to embedment and the
dropping of reinforcement for a height should be avoided.
Reinforcement should be secured against displacement outside the
specified limits.
(8) TOLERANCES ON PLACING OF REINFORCEMENT
Unless otherwise specified by Engineer-In-Charge, the
reinforcement shall be placed within the following tolerances:
a) For effective depth 200 mm or less ± 10 mm
b) For effective depth more than 200 mm ± 15 mm
(9) TOLERANCE FOR COVER
Unless specified otherwise, actual concrete cover should not deviate
from the required nominal cover by 0, +10 mm.
Sl. No.
Diameter of Rod Weight in kg/RM
1 6mm 0.222 2 8mm 0.395 3 10mm 0.617 4 12mm 0.888
5 16mm 1.578 6 20mm 2.466 7 22mm 2.984 8 25mm 3.853 9 28mm 4.834 10 32mm 6.313 11 36mm 7.990 12 45mm 12.485
CHAPTER - 6
IMPORTANCE OF CONCRETE COVER
CHAPTER - 6 IMPORTANCE OF CONCRETE COVER
In addition to integrity, strength and other design requirement, durability
of structure during its design life is extremely important. No matter care
have been exercised while designing the concrete mix, formwork and
effective methods have been used for placing, consolidating and curing
of concrete. But if care towards required concrete cover is not made
than the efforts made towards all the above could loose their
significance, which result, pour durability of structure. The importance of
concrete cover is more significant in structures located in aggressive
environment. The cover also protects the reinforcement to get it exposed
in environment and prevent formation of oxygen concentration cell,
which is the major reason for starting the corrosion of reinforcement.
Site engineer must understand the importance of the concrete cover and
necessary care must be exercised to ensure it as per drawing
requirement.
Following care shall help in achieving the above objectives: -
1. Proper alignment of formwork and re steel at location, to be
ensured.
2. Concrete cover block should be of similar mix design.
3. Proper cover blocks in columns, beam bottom, beam side and slab
as per drawing requirement.
4. Additional cover requirement for the structure where it is exposed
to sea, aggressive environment or alternate drying and wetting,
should be given due care as per drawings requirement.
5. Specific care to be ensure during vibration of concrete, so that
concrete cover block remains intact as placed.
6. Cover blocks must be properly tied to the reinforcement.
7. Properly cured cover blocks only to be used at site. There fore, as
per requirement of cover block site engineer must ensured that
they have to be casted well in advance.
CHAPTER – 7
POUR PLANNING
CHAPTER – 7 POUR PLANNING
It is needless to say that any work whether construction activities or our
day-to-day activities, requires specific plans for completion of the same
successfully.
This facilitates: -
??Total under standing of the work.
??Various requirements at different stages of execution of the work.
??Sequence of the work to be followed.
??Proactive approach of attending possible hindrances if any.
??Developing an over all aptitude for systematic approach for
completion any work.
The brief description regarding pre requisite for pour planning and w.r.t
supervision of Civil Engineering Construction is summarized below: -
POUR PLANNING: -
Pour planning refers to ensure systematic arrangement of all
requisite to take up a defined work within schedule time and
preferably ahead of schedule plan.
FOLLOWING ARE REQUISITE FOR PLANNING OF A
POUR.
A. IDENTIFICATION OF POUR. These include identification of: -
i. Location of a pour in a building and reference grids.
ii. Elevation.
B. AVAILABILITY OF LATEST DRAWINGS: -
It is required to check the latest revision of referred drawings and
also following details: -
i. To check for DCN if any.
ii. To check for FCN if any.
iii. To check for ECN if any.
iv. To check the hold in the drawing if any.
v. To check the reference drawings listed in the drawings.
C. Quantum of the work: –
Depending upon the size and importance of the pour, following
information helps for effective pour planning: -
1) Quantity of concrete to be done in single stretch.
2) It is preferable to have plan for the daily activities to be completed
w.r.t. the schedule date of pouring.
D. DAILY ACTIVITIES HELPS US TO KNOW ABOUT THE
FOLLOWING: -
??Total no of sub activities required to be done within schedule
time.
??Total quantity of material required being handle.
??Sequencing of activities can be planned effectively.
??Requirement of equipments / machinery can be plan.
??Requirement of construction material and their availability
schedule.
??It also ensure NPCIL acceptance of Material before actual use at
site.
??Availability of qualified manpower for various construction
activities. Work procedure duly approved.
??Various requirement for sub activities to be identified for: -
?? Pre construction
?? During construction
?? Post construction.
E. DEPLOYMENT OF MACHINERIES: -
Since requirements and pour size has been frozen, pre planning of
deployment of machineries is to be ensured with following details: -
??Availability of machineries on the day of concreting.
??The conditions of equipment - Whether break down or working.
??Availability of qualified crew to handle the machineries during
construction
??Availability of manpower for maintenance, if there is breakdown
during execution of work.
??To ensure the safe access for deployment of machines at site
including: -
F. AVAILABILITY OF AREA LIGHTING AND PROPER
ILLUMINATION AT WORK SITE.
G. ENSURING SAFE ACCESS.: -
Inspection of access for ramps, any intervening obstacles from batching
plant to site and at site up to pouring point.
H. Stand by arrangement in case failure of
equipment/Mechinary / Lighting arrangement.
I. Arrangement of Sun / Rain protection.
J. Arrangement for green cutting requirement and avalibility of
approved material for green cutting.
K. Availability of required number of mould for concrete cubes /
Cylinder as per requirement.
L. Review of improvement of pour plans done for earlier pours
w.r.t effective out put obtained v/s planned.
M. Necessary alteration or addition in requirements based on
the review as per Para – L above
CHAPTER – 8
POUR CHECKING
CHAPTER –8 POUR CHECKING
The pre construction stage can be broadly classified as Pour Planning
stage and Pour Checks stage.
??Once pour is planned, it is required to check the various sub
activities listed earlier in chapter – 4 in parallel for speedy
clearance of the pour.
??This is ensured to avoid any delay required for rectification if any
after pour is ready.
Following procedures is to be followed during pour
checking: -
A. SITE REGISTER: - During parallel checking record of sub activities
are to be cleared or observation to be recorded requiring rectification.
This should be maintained at site regularly.
B. Pour Card: - This gives pour inspection information. This enables to
know about all concerned officials have extended their clearance for
the specific pour.
A Checklist can be prepared for specific activities, which shall help for
clearing the pour card.
C. Drawing control record: - Reference drawing must be checked
with updated drawing control record. Further ECN, DCN, FCN, or hold
if any between various grids and elevation also needs to be checked.
Details of pour plan and sequence of concreting to be done at site
and must be properly defined before start of the work.
D. Other requirements: - Following information is also to be identified
before start of the work.
??Type of finish required.
??Slope and its extent on the surface of concrete.
??Location of sump in a pour if any.
??Location of green cutting requirement in a pour.
??Level of bulb of PVC water stops, its location and alignment.
??Location and alignment of EP’s.
??Planned schedule for availability of workers during and
immediately after the concreting. If required the shift
arrangement must be ensured.
??In addition to above following details are also important for Site
Supervisor / Site Engineer
??Concrete requisition slip shall be given at least 24 hrs. in advance
for all major pours to ensure availability of approved construction
material.
??Pour card clearance should be ensure before start of the work.
??Assessment of job hazard and preventive measures to be ensured
by Site Engineer.
??Aptitude for safety and house keeping helps for faster and safer
completion.
??Post-concrete inspection report to be prepared for all major pours.
E. Following are also required before start of concrete: -
??To ensure availability and functioning of vibrators.
??Proper walkways.
??Adequate Lighting arrangement.
??Availability of walky talkies / Phones.
??Covering material, for sun / rain protection.
??Dewatering arrangement: - If work is being done during the
monsoon and at lower elevation.
??Stand - by arrangement of machineries to be ensured before start
of the work.
??Stand - by arrangement of power supply to be ensured before
start of the work.
??Ensure the availability of supervision staff for next few hours after
last concrete is placed at site to maintain proper finishing, slope,
etc as per requirement.
??Awareness of reporting system to whom matter to be informed, in
case of emergencies. (Knowledge of telephone nos. of immediate
superior official is essential.)
??During pour checking apart from the above requirement should
important for a site supervisor / site engineer.
??Pour card i.e pour inspection clearance.
??Assessment of job hazard and preventive measures.
??Aptitude for safety and house keeping.
??Post-concrete inspection report
??Concrete requisition slips at least 24 hrs in advance to be given to
ensure, availability of approved material for the work.
??Post-concrete inspection report
??Rectification, if found any non-conformance during Post concrete
inspection.
RESPONSIBILITIES OF SUPERVISOR / SITE ENGINEERS: - CHECKING REQUIREMENT PRE CONCRETING: -
i. Site engineer has to ensure that necessary checking at the pour
wise reference to various agencies have been checked and
cleared.
ii. Assessment of safe access, approach for machineries, workers
etc is available.
iii. Requirement w.r.t ramp, slope of access & approach and skilled
manpower to handle the machineries like placer boom, concrete
pumps, vibrators, concrete pipes, and necessary stand by spare
parts is available.
iv. Proper communication system from the batching plant to the
place of pouring the concrete is available.
v. Details regarding location from grid to grid - indicating final level
/ slope or finish to be maintained is identified.
vi. Arrangement for green cutting and stand by arrangement for
concreting is ensured.
CHECKING REQUIREMENT DURING CONCRETING
i. Skilled manpower like carpenter is available to review the
position of formwork during concreting.
ii. Proper slope /levels/finishing/green cutting to be made on the
finish concrete surface.
iii. Alignment of support system of formwork needs continuous
attention during concreting.
CHECKING REQUIREMENT POST CONCRETING
Once last batch of concrete is received and placed at site, site
supervisor/ Engineer responsibility dose not ends with placement of
the final load of concrete. Before he leaves the site he must ensure
the arrangement required as per planning of the pour is available.
Further the requirement of maintain green cutting / protection of
the concrete surface from sun / rain and curing arrangement for
the area to be ensured effectively.
Post concrete inspection to done as per requirement w.r.t.
1) Alignment.
2) Dimension.
3) Levels.
4) Slopes.
5) Type of Finish.
6) Location & Levels of embedded parts.
CHAPTER - 9 BRIEF DESCRIPTION REGARDING
CONCRETE AND MIX DESIGN DEVELOPMENT
CHAPTER - 9 BRIEF DESCRIPTION REGARDING CONCRETE
AND MIX DESIGN DEVELOPMENT
WHAT IS CONCRETE: -
??Concrete is a basically heterogeneous mixture of cement,
aggregates & water along with or without admixture.
??Cement- we are using 43 –Grade ordinary port land cement.
??Aggregates –Coarse aggregates produced from main plant
excavated rock.
??Fine aggregates – Natural sand from Jhalawar river
- Manufactured sand produced at site.
??Water –
??Admixtures - Chemical admixture
- Mineral admixture
NORMAL CLASSIFICATION OF CONCRETES: -
(A) Based on density.
??Lightweight concrete (Density varies from 300 Kg/cu.m to 1850
Kg/cu.m).
??Normal weight concrete -(Density varies from 2200 to 2600
Kg/cu.m)(As per sepc. reqt. - Density = 2360 Kg/cu.m)
??Heavy concrete – (Density = 3300 Kg/cu.m) (As per our reqts.
Density = 3630 Kg/cu.m).
(B) Based on control
?? Nominal mix
?? Controlled mix
(C) Based on strength
?? Lean concrete
?? Normal strength concrete
?? High strength concrete
(D) Based on performance
?? Normal concrete
?? High performance concrete
(E) Special concretes
?? Fiber reinforced concretes
?? Polymer concretes
?? Ferro cement etc.
HIGH PERFORMANCE CONCRETE:
High performance concrete is the one, which is specially designed
to perform the intended use as per specified requirements in both its
fresh and hardened state.
??Constructability in fresh state.
??High strength.
??Impermeability in its hardened state.
According to Neville: -
“High performance concrete is concrete selected so as to be fit for
the purpose for which it is required.”
There is no mystery about it, no unusual ingredients are needed
and no special equipment has to be used. “All we use is an
understanding of the behavior of the concrete and will to produce a
concrete mix within closely controlled tolerances”.
INTENDED USE OF CONCRETE IN NUCLEAR STRUCTURES:-
??Radiological protection provided by structures: Uniform shielding
& no through cracks.
??Serviceability: By limiting deformation and leak tightness
??Strength
PERFORMANCE REQUIREMENTS OF CONCRETE FOR
NUCLEAR STRUCTUES:
MAIN PARAMETERS
??Compressive strength
??High tensile strength
??High crack resistance
??Good impact resistance
??Low permeability
??Low shrinkage
??Low heat of Hydration
??Low Creep
??Good workability
??Uniform density
??Durability.
CHARATERISTICS OF M-45 GRADE CONCRETE ??Grade of concrete – M-45
??Characteristic compressive strength – 45 mpa
??Characteristic cylinder strength – 36 mpa.
??Characteristic split tensile strength – 3.05 mpa.
??Workability at the time of placement - 175 ± 25 mm slump.
??Placement temperature less than 190 C.
What we do to achieve the intended properties in the high performance
concrete using the same ingredients it nothing but a stringent quality
control and exhaustive study/ testing of the concrete ingredients and to
have better control in selection of ingredients for HPC designing the mix
accordingly.
MATERIAL TESTING REQUIREMENTS FOR HPC.
??Cement: Ordinary Portland cement –43 grade – confirming to IS
8112
??Coarse Aggregates
??Fine Aggregates
??Water
??Admixtures
a) Chemical Admixtures: - As per ASTM C-494 –99
??Type – A- Water reducing admixtures
??Type-B- Retarding admixtures
??Type-C- Accelerating admixtures
??Type- D- Water reducing & retarding admixtures
??Type-E-Water reducing & accelerating admixtures
??Type-F- Water reducing & high range admixtures.
??Type-G- Water reducing, high range and retarding admixtures
b) MINERAL ADMIXTURES: -
??Fly ash
??Silica fume
??Combination of fly ash & silica fume
BASIC STEPS FOR DESIGNING CONCRETE
MIXES AS PER IS 10262
?? TARGET STRENGTH FOR MIX DESIGN: -
fck = fck + 1.656
fck = Characteristic compressive strength at 28 days.
s= Standard deviation for each grade of concrete.
Characteristic strength is defined as that value below which not more
than 5% results are expected to fall.
Code provides values of standard deviations for various grades of
concrete as per degree of control
Mean str. x = ex
n
Standard deviation e = e (x-x)2
n-1
Coeff. Of variation = ? x 100
x
1.65á
MEAN
95%
B) SELECTION OF WATER CEMENT RATIO: - Water cement ratio
may be selected based on concrete target strength for different cement
strength & the same is to be checked according to limitations given for
environmental exposure conditions by IS code IS 456-2000.
C) ESTIMATION OF ENTRAPPED AIR:
Max size of agg. (mm) concrete Entrapped air % of volume of 10 3% 20 2% 40 1%
a) Selection of water content & fine to total aggregate ratio from
tables given in IS code according to max. size of aggregates.
b) From water qty. – Calculate cement from W/C ratio.
Min. cement content to be ensured as per durability requirements
fixed by IS under the specified environmental exposure
conditions.
c) Calculate volume of aggregates content in the mix
d) Doses of admixtures and final adjustment of water content
maintaining w/c ratio as per workability requirements are
established based on actual trials in which minor adjustment are
to be done in aggregates quantity to ensure correct yield.
e) Temperature requirements can be met by the addition of ICE
replacing equal qty. of water depending on concrete ingredient
temperatures & ambient conditions.
ACCEPTANCE CRITERIA AS PER IS 456-2000 Compressive strength – (a) Mean strength determined from any group of four consecutive test
results complies with the appropriate limits – in column 2 of table
below: -
(b) Any individual test result complies with the appropriate limits in
column 3 of table below.
Specified grade Mean strength for (a)
(N/mm2) Individual test
results in (N/mm2) M15
=fck + 0.825 x ? or fck + 3 (N/mm2) which ever is greater
=fck –3 (N/mm2)
M20 Or
=fck + 0.825 x ? or =fck –4 (N/mm2)
Above
fck + 4 (N/mm2) which ever is greater
HPC should performs satisfactorily in the working environment during its
anticipated exposure condition during service: -
THE FACTORS INFLUENCING DURABILITY INCLUDE: -
a) The environment
b) The cover to embedded steel.
c) The type and quality of constituent’s materials
d) The cement content & water /cement ratio of concrete.
e) Workmanship to obtain full compaction & efficient using.
f) The shape & size of the member
(a) ALKALI AGGREGATES REACTION: -
ALKALI SILICA REACTION – Alkali react in the silica
(amorphous or partly crystallized) resulting in swelling causes an
expansive pressure.
SiO2 + NaOH + nH2O ----- Na2 SiO3 . nH2O
(b) SULPHATE ATTACK The main chemical reaction is the forming of tricalcium sulfo
aluminates hydrate as follow:
3 CaSO4 + 3 CaO.Al2 O3 + nH2O= 3 CaO.Al2O3.3 CaSO4.30-32 H2O Due to its high amount of crystalline water, this compound is
highly expansive. The expansion causes the concrete to crack.
CREEP: - Creep can be defined as “the time dependent increase in
strain without increase of stress i.e. under sustained stress.
Under sustained stress with time the gel, the absorbed water
layer, the water held in the gel pores and capillary pores yields, flows &
readjust themselves which behavior is termed as creep in concrete.
Age of loading Creep coefficient ration of
ultimate creep strain plastic strain
7 days 2.2 28 days 1.6 1 year 1.1
SHRINKAGE:
a) Plastic shrinkage
b) Drying shrinkage
Total Shrinkage strain = 0.0003
CHAPTER - 10
REQUIREMENT FOR CONCRETE PRODUCTION, TRANSPORTATION, AND
PLACEMENT.
CHAPTER - 10 REQUIREMENT FOR CONCRETE PRODUCTION,
TRANSPORTATION, AND PLACEMENT. It is important for Site Engineer/ Site Supervisor engaged in the Civil
Engineering construction that the required quality of the work should be
obtained while executing the work. Out of the total Civil work, concreting
constitute the major part of the work hence required to exercise due
care while production of concrete either through a Batching Plant or
Concrete mixer, transportation of concrete either through manually or
mechanically by transit mixers and placement of the concrete to the
desired location in a pour either through manually or machineries i.e by
crane or through a concrete pump or placer booms or through a chute.
Awareness regarding the requirement at every stages are to be decided
based on the requirement and mode of production/ transportation /
placement methods for concrete. Following are few areas requirements
are listed for exercising care by Site Engineer for the above for effective
and desired output.
A. CARE REQUIRED DURING PRODUCTION OF CONCRETING: -
The care required during production of concreting depends on various
factors.
1. Based on the production of the concrete.
Using concrete mixtures
Using batching plants.
2. Depending on the weather condition i.e. is hot weather concreting
or cold weather concreting.
3. Based on the time of concreting i.e. concreting done during day or
night.
4. Based on distance of batching plant from the point of placement
5. Based on the mode of transportation proposed i.e. manual /
through transit mixture.
6. Based on the mode of placement of concrete i.e. by manual/ by
crane / by concrete pump / placer boom / by chute etc.
7. Based on the Rate of pour required.
8. Based on the vertical drop of concrete from batching plant in to
transit mixture.
a. In addition to above site engineer required to ensure the
following based on the requisition of concrete received for
production of concrete.
i. Availability of tested and approved construction material in required
quantity.
ii. The safe access for transportation of construction material to
batching plant / concrete mixture.
iii. Availability of power supply / DG supply / diesel fuel etc for running
the batching plant / mixture for the desired duration.
iv. Based on the past record of batching plant /mixture for production
of concrete for no. of running hours / cumulative concrete
production in cu. m., availability of spare parts to be ensured which
needs frequently repair / replacement to avoid any delay during
concreting.
v. Availability of supporting machines like welding arrangement, skilled
/ unskilled crew for repairing the system.
vi. Proper calibration of batching plant / weigh batcher prior to start
the work. This is generally done at fixed frequencies.
vii. Required rate of pour.
viii. Ensuring safety aspects at batching plant.
ix. Proper illumination and communication system at batching plant for
effective coordination with engineers at point of placement.
B. CARE REQUIRED DURING TRANSPORTATION OF CONCRETE: -
The care required during transportation of concrete depends on various
factors: -
1. Mode of transportation, i.e based on the mode of transportation
proposed i.e. manual / through transit mixture.
2. Based on distance of batching plant from the point of
placement.
3. Based on the mode of placement of concrete i.e. by manual/ by
crane / by concrete pump / placer boom / by chute etc.
4. Depending on the weather condition i.e. is hot weather
concreting or cold weather concreting.
5. Based on required rate of pour.
6. Based on stand by arrangement of transit mixers.
7. Based on arrangement for availability of fuel, proper air pressure
in tyres condition of transit mixers.
8. Based on safe access from batching plant to point of placement
and necessary turning areas for transit mixers safely at site.
9. Walkie - Talkie to be provided in transit mixers for effective
coordination.
10. Restriction of traveling speed of loaded and empty transit mixers
11. Ensure availability of water in water tank of transit mixers for
immediate cleaning after concreting is done.
12. Sun protection of transit mixers and its pipes with gunny bags
and ensuring the wetness of the same.
C. CARE REQUIRED DURING PLACEMENT OF CONCRETE: -
It is the most important criteria of concrete since it decides the final
quality and strength of concrete is structures.
The cares required during placement of concrete are as follows: -
1. Required consistency to be maintained from the point of
production to point of placing. RPM of transit mixture should
be around 4-5 RPM.
2. Ensure safe access for labours / skilled workers.
3. Ensure planned arrangement of layout of concrete pipe
route.
4. Ensure Sun / Rain protection for green concrete.
5. Ensure proper arrangement of vibratos.
6. Ensure the location of EP’s / Water stop / level of concrete
etc as per drawing during concreting.
7. Ensure type of finish and slope required in concrete.
8. Ensuring the green cutting application within planned
duration after concreting is done.
9. Ensure that no cold joints should form.
10. Use of cement slurry to maintain the concrete green in case
of delay in receiving the successive batch of concrete at site.
Keep the check on time taken from batching plant to the
time at point of placement w.r.t consistency and
temperature.
11. Avoid over vibration in concrete.
12. Avoid vibration of initially hardened layer over which new
concrete is been placed.
13. Maintain all safety aspects particularly while working in
height and hazardous area.
14. Ensure proper illumination and communication.
15. Have leadership quality during difficult situations at site
especially work done in night hrs/ total power cut situation /
during any accident at site / during any industrial relation
problem at site.
CHAPTER - 11 POST-CONCRETE INSPECTION
CHAPTER - 11
POST-CONCRETE INSPECTION Responsibility of Site Engineer is not only to ensure proper pour planning
and effective execution of the work but also to ensure that desired
results w.r.t quality of the work, i.e finishing, slope, alignment and
bulging etc.
After formwork is removed site engineer must ensure the following w.r.t
post concrete inspection.
1. Depending up on the tolerance available as per drawing and
specification post concrete inspection to be made very next day
after removal of the formwork.
2. Depending upon inspection testing plan record must be generated
to have specific identification of nonconformance noticed beyond
the acceptable limit.
3. Specific attention is given in the following area particularly: -
DEFECTS IN THE CONCRETE NOTICED.
i. Identification of honeycomb portion.
ii. Identification of bulging beyond the acceptable limit.
iii. Identification of poor finish achieved against requirement
beyond the acceptable limit.
iv. Identification of improper slope in the concrete floor against
requirement beyond the acceptable limit.
v. Identification of poor construction joint needs immediate repair
and attention to make it ready to received next course of
concrete.
vi. Identification of projected reinforcement or any other support
casted for giving support of formwork needs to be treated
properly after the purpose achieved for which it has been left.
vii. Identification of tie holes which is to be repaired immediately
before going ahead for next pours.
viii. Removal of the left shutter / formwork piece / gunny bags etc.
to be ensured, from concrete surface.
ix. Identification of location of critical EP’s if it is dislocated from the
position or identification any left out of EP’s if due to over sight
or mismatch in the drawings.
x. Identification of the location of the PVC water stop and their
joints.
xi. Identification of cracks to be ensured along with the comments
if it is serious.
xii. Identification of grouting nozzles etc to be made which have to
be placed before next course of concrete.
xiii. It must be ensured that scaffolding, pipes, other construction
material should not be stacked on already constructed walls /
locations where further pours are to be done and PVC water
stop is partly embedded. This shall protect the PVC water bar
from getting damaged.
Necessary non-conformance to be issued for repair and rectification and final inspection to be made to ensure correctness of the above issues.
*****
CHAPTER - 12 VARIOUS TYPES OF FINISHES
IN CONCRETE
CHAPTER - 12 VARIOUS TYPES OF FINISHES IN CONCRETE Various construction requirements particularly for the surface finish are decided based on the functional requirement / Aesthetical requirement in structure. VARIOUS TYPES OF FINISHES IN CONCRETE: -
Type of Finishes in concrete: -
(1) Formed Surface
Finish F1: - Shall apply to all formed surfaces for which finish F2, F3 or
any other special finish is not specified. Finish F1: - Shall include filling
all form tie holes.
Finish F2: - Shall apply to all formed surfaces so shown in the drawings
or specified by the Engineer. Finish F2- shall include filling all form tie
holes repair of gradual irregularities exceeding 6 mm, removal of ridges
and fins and abrupt irregularities by grinding.
Finish F3- shall apply to all formed surfaces exposed to view or where
shown on the drawings or specified by the Engineer. Finish F3- shall
include all measures specified for finish F2 and in addition, filling air
holes with mortar and treatment of the entire surface with sack rubbed
finish. It shall also include clean up of loose and adhering debris, where
a sack rubbed finish is specified, the surfaces shall be prepared within
two days after removal of the forms. The surfaces shall be wetted and
allowed to dry slightly before mortar is applied by sack rubbing. The
mortar used shall consist of one part cement to one and one half parts
by volume of fine (IS No 16 mesh) sand. Only sufficient mixing water to
give the mortar a workable consistency shall be used. The mortar shall
then be rubbed over the surface with a fine burlap or linen cloth so as to
fill all the surface voids. The mortar in the voids shall be allowed to
stiffen and solidify after which the whole surface shall be wiped clean
with burlap so that the entire surface presents a uniform appearance
without air holes and irregularities.
Curing of surface shall be continue for a period of ten days.
2) UNFORMED SURFACES
Finish U1 Finish U1 requires the surface in the specified slope /grade and
the gradual surface irregularities not exceeding 6 mm when measured
with respect to a plane surface parallel to slope with a template 300 mm
long.
Screeding the surface of the concrete to the required slopes and
grade as specified on drawings. Surfaces to be covered with concrete
topping, terrazzo and similar surfaces shall be smooth screeded and
leveled to produce even surface, irregularities not exceeding 6 mm.
Finish U2
Requirements shall be same as for U1 finish except the abrupt
irregularities shall be repaired slope and grade. The surface shall have
wooden finish.
Finish U3
Requirement shall be same as for U2 finish except that the
surface shall have steel trowel finish and the edges of the concrete shall
have the finish with edging tools.
Repair of gradual irregularities exceeding 6 mm, finishing joints
and edges of concrete with edging tools.
SURFACE PREPARATION FOR CONCRETE Site engineers must ensure the following points for surface preparation
while proposing concreting against rock surface or existing concrete
surface.
(A) Rock Surface (i) Inspection of rock surface for soundness.
(ii) Cleaning of the surface to receive concrete.
(B) Concrete Surface (i) Surface preparation: -
a) By Green Cutting
b) By Chipping
c) Cleaning of the surface
(ii) Wetting of the surface prior to concreting.
Chapter - 13 DEFECTS IN CONCRETE AND ITS
REPAIR
CHAPTER – 13 DEFECTS IN CONCRETE AND ITS REPAIR
Post concrete inspection is a tool to identify the possible general defects
in newly hardened concrete. The typical defects are: -
a. Occurrence of surface blemishes.
b. Honey comb.
c. Cavity holes due to tie rods.
d. Various types of cracks in concrete.
i. Plastic shrinkage cracks.
ii. Plastic settlement cracks.
iii. Drying shrinkage cracks etc.
A. Occurrence of surface blemishes.
The exposed surface area of concrete is blemished when spots or area
vary noticeably and detract from the appearance of surrounding surface
areas. Before treatment of blemishes, the contract documents should be
referred to for identifying the acceptable level of blemishes for the
various surface to be produced under the terms of given in the contract.
Any repair process for treatment of blemishes so chosen should also be
evaluated to determine if it would produce a less apparent and more
pleasing appearance than the original blemish
Repair
When concrete surface is noticed with air bug holes: -
Site engineer can follow either of the following methods for corrective
action.
1) Sack rubbing to repair the blemishes and the fill air bug holes.
2) Action should be such that the treatment is less apparent and
more pleasing appearance.
3) Such treated surface should be cured properly
B. HONEY COMB: - During concreting if the voids left in the concrete
due to failure of mortar to effectively fill the space among coarse
aggregate than structure is said to have defect of honeycomb. Such
defects occur due to: -
? ?Congested reinforcement.
? ?Improper vibration.
? ?Difficult construction.
? ?Improper mix i.e. improper aggregate ratio of fine aggregate to
total aggregate.
? ?Leakage of slurry from formwork gaps or damaged formwork.
Site engineer can follow the either of the methods to minimize the
defects: -
? ?Ensure proper vibration.
? ?Ensure proper consistency using water-reducing admixture to
increase slump.
? ?Ensure no gaps in the formwork to prevent slurry leakage.
? ?Using polymer modified cement sand mortar – by hand of
toweling – this method can be used if honeycomb is less than
concrete cover.
? ?If it is more than concrete cover that the area must be chipped off
and concrete must be replaced with normal insitu concrete of
same grade.
C. Cavity holes due to tie rods.
Tie rods, made of reinforcement steel, are often used to ensure that
the form assembly remains intact when subjected to concrete
pressure during concreting process. These tie rods are fixed with
cones at both ends. These cones are open from outer end hence,
when the formwork is removed, they are visible as holes. As this rods
are made of reinforcement and their ends are open to atmosphere, if
left expose for a long period, they are susceptible to correction.
? ?Repair method: - By dry pack mortar
CRACKS IN CONCRETE
CRACK IN CONCRETE: - This defect permits the ingress of aggression
agent in the structure and adversely affect.
A. The durability.
B. Water tightness.
C. Integrity of structure i.e. strength
Sound transmission: - Crack trough NDT techniques
D. Various types of cracks in concrete.
PLASTIC SHRINKAGE CRACKS: - This caused due to repaid loss of
moisture due to temperature of ambient air and concrete, relative
humidity and prevailing wind velocity at the surface of concrete.
Site engineer should take following precautions to prevent rapid moisture
loss due to hot weather and dry wind.
I. Covering the concrete by plastic sheet.
II. To provide sunshade during concreting.
III. Use fog nozzles to saturate air above green concrete surface.
IV. Use of windbreaker to reduce wind velocity.
PLASTIC SETTLEMENT CRACKS: -concrete is consolidated after initial
placement vibration and finishing. The plastic concrete generally give
local retrain by reinforcement etc. and result cracks or known as plastic
settlement crack.
Site engineer should follow following preventive measure to minimize the
plastic settlement cracks.
??Maintain proper cover in concrete.
??Provision of time interval between placement of concrete in slabs
and beams.
??Use or minimum slump concrete.
Drying shrinkage cracks: - When concrete is wet, it tends to expand.
It reduces its volume, when loss of moisture from cement paste occurs.
It can be explained in simple words. If this shrinkage can occur without
any restrain no cracks will appear. But combination of shrinkage and
restrain provided by another part of structure or by sub grade develops
the tensile stress in concrete. This is resulting in crack known as drying
shrinkage crack.
Site engineer should follow the following methods to reduce
this effects: -
??Use less w/c ratio in a concrete mix.
??Use large amount of aggregate.
??Proper consolidation of concrete.
REPAIRING OF CRACKS: - In spite of precaution observed some
times cracks are seen in the concrete surface and needs repair. The
repairing of cracks mainly depends on: -
??Location and width of cracks.
??Extent of crack
??General condition of concrete.
Following methods can be used for repair of cracks: -
1) GROUTING: - Wide crack can be filled by either cement grout or
various chemical grouts.
2) Dry packing: - Method used for minor dormant cracks but not
effective for active cracks.
Cracks are widened to a slot of 15-20mm vide and 20-25 deep with
base width slightly more than surface width. This is packed by
cement mortar with low w/c ratio.
3) Gravity filling: - Cracks can be filled upto with low viscosity
epoxies.
4) Routing and sealing: - This method is used where structural
repair is not necessary. This procedure is more accurate for flat
and horizontal surface like floors / pavements. These methods can
be commonly used for water proofing by sealing cracks on
concrete surface on concrete surface, where water stands or
hydrostatic pressure applied.
5) Injection grouting: - Repairing of narrow crack width upto 0.05
mm can be done. In this method GI or PVC nozzle is drilled in the
cracked over upto depth of thickness of half the member and
grouting is done.
Every Engineer has to deliver the output based on the requirement and
facing the challenges to meet the quality standards with optimum use of
manpower. It is need less to say that in a competitive environment, the
restricted and compressed time schedule, the structural adequacies for
the various problems are need to be reviewed as listed below: -
(1) Overall strength and stability of the structure.
(2) Surface finish and appearance of the structure i.e. cracks
leaching discoloration etc.
(3) Effect of leakage /seepage and effect of un-stability due to
local parameters like improper backfilling/ undulations etc.
(4) Durability with respect to corrosion, carbonation and sulphate
attack.
Various type defect and damages in structures have been noticed over a
period of time in various localities this has resulted a need for an
Engineer to understand these defect and their respective possible
causes. Responsibility is not only limited to identification of the damages
but require to recommend necessary corrective measures including
investigations if necessary.
Brief details of defects and damages occurred in concrete are
indicated below along with their possible causes and suggested
investigations for ready reference: -
CONCRETE
Visible Defect Possible Causes Investigation Suggested
Rust on surface. Iron compounds in
aggregates, nails/wires
left in formwork.
Chemical analysis of
samples.
Rust stains on surface. Corrosion of binding wires,
corrosion of reinforcement
steel.
Check cover and
carbonation of concrete.
Cracking of concrete
cover, exposure of
reinforcement and
spelling of concrete
Corrosion of reinforcement
and other steel due to
moisture and chloride
ingress, frost attack and
poor quality of concrete
low density, high porosity
and high water to cement
ratio).
Check cover, test for
chlorides and
carbonation, check
reinforcement adequacy.
Surface crazing. Concrete Mix too wet and
poor curing.
Check concrete mix and
construction method
used.
Random diagonal
cracking, lateral
cracking at equal
spacing
Inadequate protection
against shrinkage, over
rich or over wet and non-
cohesive concrete.
Check reinforcement,
spacing of joint, analyze
samples of concrete.
Repetitive vertical or
horizontal cracks.
Joint spacing too large. Examine joint
details/spacing check
concrete sample and
aggregates used.
Wet and damp spots,
deteriorated applied
finishes without
cracking.
Honeycombs due to poor
placement of concrete
mix, poor compaction or
water stopper missing.
Check concrete after
recovering applied
finishes, checks detailing
of joints, check for water
stopper, test and analyze
concrete.
Cracks at intervals. Restrained shrinkage,
reinforcement too near
the surface, corrosion of
reinforcement, moisture
movements.
Check spacing of joints
9design), check
distribution of
reinforcement, concrete
sample.
Faulty movement joints,
faulty or missing water
stopper, inadequate or
improperly constructed
join, inadequate
reinforcement.
Check concrete at joints,
check water bars and
reinforcement details.
Rust stains below
mortar covering of
external pre-stressing.
Tendon corrosion, poor
grouting of tendons.
Check location/ extent of
corrosion.
Map cracking. Alkali-silica reaction (ASR),
early drying out
conditions, over rich
mixes, over compaction
and poor curing.
Check concrete
constituents, pertographic
analysis.
Surface abrasion. Excessive wear. Check abrasive loading,
check quality of concrete
surface, check history of
usage.
Cracking or spelling
with or without staining
(generally parallel to the
direction of
reinforcement steel).
Corrosion of reinforcement
steel or pre-stress tendons
corrosion of encases steel,
alkali silica reaction (ASR),
restrained by
reinforcement.
Check condition of
embedded steel, check
cover, carbonation,
chloride content, check
presence of ASR.
Deflection. Shrinkable aggregate,
premature removal of
formwork, overloading.
Analysis of concrete
samples design check.
Local settlements along
with diagonal cracks on
footings (foundation)
Poor sub grade
compaction, inadequate
reinforcement, ground
movement due to water /
erosion/ mining/ shrinkage
clays, peat or other
causes.
Investigate foundation
design and substrate.
Vertical or slightly
inclined cracks on sides
and soffit on central
part of RCC beams.
If less than 0.3 mm:
Normal if wider than 0.5
mm: Overload, excessive
shrinkage of slab,
premature removal of
props.
Check design, compare
actual load with design
load, check span/ depth
ration with codal
requirements, check
temperature gradient
Diagonally inclined
cracks in beams,
generally at or close to
the supports.
Overloading, inadequate
beams depth,
inadequately provided
reinforcement to prevent
shear.
Check actual shear
resistance against codal
allowance.
Vertical cracks in RCC
beams at regular
intervals.
Shrinkage around stirrups.
Helical cracks in RCC
beams face and
extending around the
section perimeters.
Tensional shear stresses. Check actual tensional
resistance against codal
requirement
Excessive deflection of
RCC beams.
Inadequate depth,
overloading, formwork
defect, inadequate or
displace reinforcement,
shrinkable aggregate,
materials defective or
deteriorated, bond failure
between reinforcement
and concrete.
Check span/depth ratio
with codal requirements,
compare actual and
theoretical deflections,
check loading history,
cover meter check, test
concrete, check for
defects in construction.
Pre-stressed concrete
beams with excessive
deflection, excessive
handing, loose or
defective anchorage
segment separation,
grout disturbance and
distribution not proper,
segmental shear cracks.
Overloading, overstressing
or poor concrete,
inadequate pre-stresses,
displaced tendons,
material defective or
deteriorated.
Check deflection, and
stresses against actual
load, check conditions of
all tendons, check design,
check cover by cover
meter.
Bowing of pre-stressed
columns.
Distortion during erection,
concrete creep or
shrinkage, tendon
fractures, defective
material or material
deterioration.
Check loading conditions,
check design and
construction defects,
check cover by cover
meter, check tondon
condition at any fracture.
Excessive deflection in
slabs and / or heaving
of tiles or cracking of
tiles on the top surface.
Inadequate depth,
overloading, for long
period, defective
formwork, inadequate or
Check span/depth ratio
with code requirements,
compare actual and
theoretical deflections,
displaced steel
reinforcement, material
defective or deteriorated,
lack of continuity.
check loading history,
check cover by cover
meter, check for
shrinkable aggregates.
Cracking of slab and /
or finishes over
supports.
Plastic and drying
shrinkage cracks, slab
designed as simply
supported but constructed
as continuous or with
fixed supports, inadequate
top reinforcement in
continuously designed
slab, excessive support
memento relaxation,
inadequate top steel at
supports, top steel
displace.
Check design, check
construction defects and
cover by cover meter.
CHAPTER - 14 VARIOUS TYPES OF JOINTS
CHAPTER - 14 VARIOUS TYPES OF JOINTS
The site engineer is required to complete the work as per drawing
requirement to the minimum possible time. It is a fact that the entire
work can not be completed in just single pour due to the constraint of
non availability of resources as per requirements, due to technical
reasons i.e considering thermal strain and expansion & contraction
properties of structure. Generally there are following types of joints are
to be handled during Civil construction.
1) CONSTRUCTION JONTS: -
2) EXPANSION JOINT AND CONTRACTION JOINT: -
3) COLD JOINT: -
CONSTRUCTION JONTS: -
Construction joints occur wherever concreting is stopped or delayed and
when the fresh concrete placed against hardened concrete subsequently
cannot be integrated into previous by vibrating. Horizontal construction
joints occur at levels between two successive lift of concrete, whereas
vertical construction joints occur where structure of such length that is
not feasible to place the entire length in one continuous operation.
Construction joints, are required by the construction operation.
Construction joint locations depend on sequence of concreting
operations or are part of the contract drawings. Construction joint
location need to be planned ahead of placing of concrete and should
adhere to those pre identified locations. Generally, they mark the top of
a lift, the end of a monolith, or the end of a days work. They should be
properly located and well bonded.
The following factors are to be considered for location and treatment of
construction joints to make them perfect and avoid cold joints.
??When the work is to be interrupted, horizontal and vertical
construction joints and bonding keys should be located in
conformity with the relevant contract specifications/drawings.
??Construction joints should be located in the floor slab and beams
near the middle of the span (where the shear is least) and should
be vertical in the absence of provisions in construction drawings.
In a column, the joint should be formed about 75 mm below the
lowest soffit of the beams framing in to it.
??Because construction joints frequently leak and degrade in the
weather, as far as possible, they should be avoided. Before fresh
concrete is placed. Existing concrete surface must be made rough
by hacking or green cutting.
??The rough surface should be thoroughly wetted for about two
hours and should be dried and coated with 1:1 freshly mixed
cement –sand slurry, immediately before pacing the new
concrete.
GREEN CUTTING FOR CONSTRUCTION JOINT TREATMENT: -
Where higher degree of quality of construction joint treatment is
required as per contract specification/or drawings, green cutting should
be applied. The entire construction joint should be treated by Green
cutting using air / water jet at a suitable pressure to remove the laitance
from the green concrete surface to received subsequent pour of concrete
over it. A suitable, approved brand of surface retarder should be used to
retard setting time of green concrete to a depth of 5 to 8 mm. Green
cutting should b done only after the final setting of concrete, so that the
additional water available from air water jet used for green cutting on
the surface does not harm the quality of the concrete. Prior to
commencement of the green cutting operation, a mockup should be
made for each grade of concrete, with different types of cement and
different kinds of exposure of the proposed construction joint.
EXPANSION AND CONTRACTION JOINTS: - Expansion and
contraction joints should be strictly as per the relevant construction
drawings only. Line and level of water –stop and expansion boards, if
any at these joints should be safeguarded from damage or dislocation
during placing and consolidation of concrete.
*****
CHAPTER - 15
ASSESSMENT OF SAFE WORKING CONDITIONS
WHILE EXECUTING THE JOB.
CHAPTER–15 ASSESSMENT OF SAFE WORKING
CONDITIONS WHILE EXECUTING THE JOB. Responsibility of Site engineer with respect to safety requirements at site is most important parameter. Every site engineer must ensure availability of safe working condition while executing the job. Following few areas must be given attention.
1. Suitable scaffolds shall be provided for workmen for all works
that cannot safely be done from the ground..
2. Scaffolding or staging more than 3.5 m above the ground or
floor, swing of suspended from an overhead support or erected
with stationary support shall have standard guard rail properly
attached bolted, braced or otherwise secured at least 1.0 meter
high above the floor or platform of staging..
3. Working platforms of scaffolds shall have toe boards at least 15
cm in height to prevent materials from falling down.
4. Working platform, gangways and stairways shall be so
constructed that they shall not sag unduly or unequally
5. Safe means of access shall be provided to all working platforms
and other elevated working places
6. Adequate precautions shall be taken to prevent danger from
electrical lines and equipment. No scaffolding, ladder, working
platform, gangway runs, etc. shall exist within 3 meters of any
uninsulated electric wire.
7. Proper house keeping must be maintained at site.
8. Necessary personnel protective equipments must be used while
working.
9. Safety work permits to be ensured while working at height,
hazardous operations, work in radiation area, work in and
around water body.
10. Slope of ladder shall not be steeper than 1 in 4 i.e. 1 horizontal
to 4 vertical.
11. Ladder shall not be used for climbing with carrying materials in
hands.
12. Due care must be taken while removal of formwork.
13. Use of safety belt to be ensured while `working at height.
14. Proper illumination and frequent checking of scaffold to be
maintained.
15. All loose material should be removed.
16. Any material having fire hazard to loose formwork pieces,
wooden block must be removed from the working area.
17. Ensure deployment of only quality and skilled manpower for
handling. The movement of construction, concrete, formwork,
re-steels pipes etc at site.
18. Ensure to avoid any temporary steep slope or ramp at site for
movement of works and machineries.
19. Maintain a house keeping culture at site. Ensure to stack all
construction material like formwork, pipes etc properly stacked
so that safe approach is maintained.
20. Construction material likes re steel, aggregate, sand, also to
stacked properly.
21. Ensure proper communication while entering in a hazardous
area.
22. Inculcate the safety as culture and habit within the group.
CHAPTER - 16
IMPORTANCE OF JOB HAZARD ANALYSIS.
CHAPTER - 16 IMPORTANCE OF JOB HAZARD
ANALYSIS. Work can only be said to complete successfully if requirements
with respect to quality have been maintained without any
accident during execution of the work. Safe working condition
not only increases the output, but also gives satisfaction and
confidence while working in any of difficult conditions.
For a Site engineer it always preferred that we must know about the
work in totality. This will help us to identify the various sub activities
involved in the work and to assess the possible hazards during executing
the work. Action required to prevent such possible hazards must be
enlisted and honest efforts must be made to avoid any unsafe conditions
during execution of the work. It is preferred that job hazard analysis
should be done before start of the work.
Sample format for job hazard analysis in given below for ready
reference.
Name of the work : -
MAJOR ACTIVITY TO BE TAKEN UP: -
Duration of the activities : -
Sr.no Activities Possible hazards Action to be
taken for
prevention of
hazards
CHAPTER - 17
AWARENESS OF QA REQUIREMENTS
CHAPTER – 17 AWARENESS OF QA REQUIREMENTS
A most impartment part for implementing any QA requirement
needs to understand about the intent and meaning of the
quality. The brief description about the terms generally used
related to QA are summarized below.
Quality: - Totality of feature and characteristic of product or service
that bears on its ability to satisfy stated or implied need.
Stated needs means contractual needs.
Implies Need means – Identifies and defined needs i.e Usability, Safety,
Reliability, Availability and Maintainability.
Specification: - Document that describes the requirement with which
the product / service has to confirm.
It should refer to – pattern, drawing, or code. Or indicate the criterion by
which checks to be made.
Checks used to confer the specification requirement.
Procedures. : - An identified and defined sequential activities to
perform the task is known as procedure. It is specified way to perform
the activity. It contain purpose and Scope, What, When, By Whom,
Where, How the activities to be done, Reference, Control Required and
record to be maintained.
Inspection: - Activities such as measuring examining, testing, gauging
are made and compared with the standard to determine the conformity
of requirement.
Quality assurance: - Adequate and proper planning and systematic
action which are necessary to provide adequate confidence that product
or service will satisfy given requirement for quality.
Quality Control: - The operational techniques are performed to full fill
the requirement of quality.
1) Monitoring a process.
2) Removes causes of conformity at relevant stages to increase
economic effectiveness
Process: - A set of interrelated resources and activates which
transforms input to output.
Quality surveillance: - The continuing monitoring and verification of
status of procedure, methods, conditions referred as quality surveillance.
In relation to stated reference to ensure that specified requirement is
made.
Quality surveillance: - Takes in to accounts the areas to deterioration
or degradation with time.
Quality System: - It is defined as organization structure management
function that determines and implement quality policy.
Quality Management: - It is aspect of overall management function
that determines and implements quality policy.
Quality policy: - It is defined overall intensions and direction of an
organization as regard to quality formally expressed by top
management.
Total quality management: -
1) It is a management approach of an organization cantered on
quality.
2) Based on participation of all its members.
3) Aiming at long-term success through customer satisfaction, and
benefits to the member of organization at safety.
Quality manual: - A document stating the quality policy and describing
the quality system of and organization.
QA Plans: - It is a systematic way of describing the extent and
responsibility for checking and acceptance of various sub activities with
respect to defined references and specification.
Quality Audit: - It is systematic and independent examination to
determine.
1) Whether the quality activities and related result comply with the
planned arrangement.
2) Whether there planned arrangement are implemented effectively
or not.
3) Planned arrangements are suitable to achieve the objective.
Site engineer must know that there are three Quality Assurance
manual in our organization.
(i) Topical QA manual: -
A document stating quality policy and describe the quality
system of total organization.
(ii) Project QA manual: -
A document stating quality policy and describe the quality
system of specific project in line with requirement stated in
topical QA manual.
(iii) Specific work related QA manual: -
A document stating quality policy and describe the quality
system of agency executing the specific job / contract in a
project in line with requirement stated in topical QA manual and
Project QA manual.
Site engineer also must ensure the following while supervising
the work: -
1) Implementation of relevant specification required for the work.
2) Implementation of work procedure for specific construction
activity.
3) Inspection and testing plan for the referred work.
4) Ensure availability and use of proper approved construction
material at site.
5) Ensure the deployment of qualified manpower at site for various
construction activities.
6) Ensure concrete pour plan arrangement as per schedule plan.
7) Proper supervision during pre execution, during concreting and
post concreting.
8) Ensure repair of defects / deficiencies, if found as per approved
procedure.
9) Ensure appropriate documentation for the work.
Effective and desired results with optimum use of departmental manpower engaged in Supervision of Construction activities is always a major concern of NPCIL vision and policy. He has provided Enthusiastic and inspiring support for development of this document
C.P. JHAMB PROJECT DIRECTOR, RAPP-5&6
Providing dedicated & committed leadership
Development of this document as handy tool and reference to requirement of Site Supervisors and Site Engineers directly connected with the work was the vision ofSh. D.K.JAIN, Chief Engineer (Civil), RAPP-5&6. This could be made possible due to his efficient and able leadership, effective guidance, continuous motivation and appreciation at every stage.
D.K.JAINCHIEF ENGINEER (CIVIL), RAPP-5&6
A man with inspiring and strong vision.
