2. IN PLANT TRAINING: REPORT
Name of student: Gayatri Ramdas
University: Amrita School of Engineering
Course: Civil III B.Tech
Doing In-Plant Training at Coromandel Engineering for 15 days (05/06/2014 to 19/06/2014)
Site –Esthell Homes, Velachery, Chennai
Project Name - Esthell Residential Complex and Mall
Client - Esthell Homes
Contractor - Coromandel Engineering
Architect - Cheralathan Associates
HR Manager - Mr Vivekanand
Type - Residential + Mall
Residential complex – 3 basements + 13 floors + terrace floor
Mall – 4 basements + 5 floors
Type of foundation - Raft foundation
Type of structure - RCC
Excavation depth - 11.05m
Scope - contractor: civil work only (along with providing the labour force with
electricity and water)
client : cement, steel, RMC
Project Value - Rs 29,88,29,929
3. Day 1: 05/06/2014
1. Introduction to staff members
2. Reading the work order; and terms and conditions of contractor’s work
3. Viva (on site-related topics in survey, construction materials, building technology)
4. Site. Saw the shoring works and shuttering of columns in the basement
Day 2: 06/06/2014
1. Erection of wall shuttering. Inclined shoring observed.
2. Erection of columns formwork in grid 53 (basement). Waterproofing materials already
included
3. Observed starting of scaffolding.
4. Cube test (compressive strength test)
- observed and noted down the values of the compressive strength of three M40 cubes
(150x150x150 mm3
)
5. Placement of one way slabs in the basement floor
Day 3: 07/06/2014
1. Calculated area of shuttering and volume of concrete used in rafts and columns.
2. Learnt to read the drawing plan of the given floor (AutoDesk product)
3. Concreting of columns
4. Removal of column shuttering in the basement floor
5. Curing carried out
Day 4: 09/06/2014
1. Learnt to calculate area of shuttering of walls and slabs.
2. Observed concreting of columns
3. Found out the unit weights of steel rods used in the site (dia – 8,10,12,16,20,25mm)
Cube Weight (kg) Load (kN) Strength (N/mm2
)
1. 8.58 630 28
2. 8.46 610 27.11
3. 8.44 750 33.33
4. 4. Calculated volume of concrete required for the retaining wall
5. Solved problems
Day 5: 10/06/2014
Not much work done at site, due to rains.
Calculated shuttering area of raft and columns and slabs. Also the weight of reinforcement for raft
(outer and inner)
Day 6: 11/06/2014
1. Started at the foundation, made the following observations:
It is a raft foundation (dia of steel rods used is 25mm. The columns start from the raft and go
on all the way up to through the floor levels. The reinforcement (dia of the steel rods)
reduces with increase in height. So it reduces every three floors
2. Columns:
A starter box is initially made (it is the base of the column) and from this starter box, the
steel rods (they are generally 12m long, can be cut to the desired length accordingly) are
placed and the column is gradually built. Stirrups are also placed (to prevent diagonal tensile
forces) one, two or three stirrups can be used in one go, overlapping each other. The leg
count is nothing but the number of overlapped layers.
Column offset drawings - done by the surveyor initially and this marks the places where the
columns are to be built. The positions are marked woth the help pf a total station and then
the offset drawings are made.
Column curtailment (CC) - the reinforcement decreases as we go upwards and sometimes,
so do the number of columns. So suppose we don’t need a column in a particular floor, then
we take the reinforcement that comes through (from the column in the lower floor) and we
bend it and join it to the slab. This is called column curtailing
Floating Columns (FC) - this is just the opposite of curtailed columns. If we need a new
column in a floor, then we start new reinforcements from the floor slab and take it upwards
to form a new column.
Shuttering - after the reinforcement is laid, the column shuttering is fixed (formwork, for the
column. 2.4m high )
concreting - the concrete is poured into the shuttering and once its set, the shuttering is
removed and the column is cured, the shuttering is then moved upwards and the rest of the
column is built. The shuttered column is supported by inclined shores. (poles, inclined props)
Head clamps are the steel rods that project out of the column through the shuttering (so
that the formwork can be bolted firmly) These give the column extra stability.
The verticality of the column can be checked by dangling a plumb bob and checking the
horizontal distance between it and the column. Should be the same everywhere.
5. 3. Beams and Slabs:
There are two types of slabs used – one way slab (L/B ratio is >2 ) and two way slab (L/B
ratio is <2 ). Two way slabs have cranks.
shorter span has the main rod, longer span has the distributors.
The general procedure is – (i) runner and beam placement (ii) slab shuttering (iii) slab rebar
work (iv) slab concreting.
For walls and columns, it’s called shuttering; for beams and slabs, it’s called centering. Tin
sheets are used and they provide the shape and structure. They are supported using props.
Loggers are wooden pieces which are used below to support the slab and the props are
vertical members that are bolted to the bottom surface to support these loggers
Beams and columns are used to give structural integrity to the building. The slabs are places
between them.
There are many types of beams, but two important types are - concealed beams and
inverted beams:
(i) Inverted beam - they come below the slab level and are clearly visible.
(ii) Concealed beam - they are hidden within the slab, not visible externally.
4. Learnt to calculate the weight of reinforcement in the raft
Day 7: 12/06/2014
1. Observed the construction of the lift well and the stair well.
2. Read the safety procedures to be followed in site. Read the Hazard Identification and Risk
Assessment booklet (HIRA)
PPE - Personal Protection Equipment are (i) helmet (ii) safety shoes (iii) safety belt (iv) jacket
(v) visor blade mask (to prevent dust/cement/wooden particles from landing on your face)
(vi) safety gloves
3. Calculated weight of reinforcements in slabs.
4. RMC is brought in a truck mixer. And transferred into the concrete pump, which pumps the
concrete to the required area through long pipes.
Day 8: 13/06/2014
1. Rebar work for the new staircase (from 1st
basement to 2nd
basement) was started
2. One set of lift well walls were completed (concreted) and the shuttering was removed and
the curing process started
3. Two columns were demolished because of honeycombing observed after removing the
shuttering
(assignment on honeycombing will be attached.)
4. Walls: they are what finish the building and provide a distinctive shape. In the basement,
there is a retaining wall that’s built for the purpose of providing extra support and resistance
6. to the soil mass around it (11.05m below ground level). There are many types of walls used –
(i) partition walls (ii) load bearing walls (iii) blank walls (iv) cavity walls (v) shear walls
Day 9: 14/06/2014
1. Concrete casting for one part of the eastern wall.
2. Removal of shuttering of the completed part of the wall
3. Staircase – barbending work was done.
Day 10: 16/06/2014
1. A batch of concrete was discarded because of wrong mix proportions and low workability.
2. Fresh batch was produced. And used for casting of retaining wall on the west side
3. Shuttering was removed (retaining wall)
4. Bar bending work was continued for the stair wells
Day 11: 17/06/2014
1. Minor honeycombing in the columns were corrected by patching with mortar and then
cured.
2. Concrete casting of the walls were carried out
3. Casings and shutters are transferred with the help of a mobile crane
Day 12: 18/06/2014
1. De shuttering of wall and curing of the same.
2. Planning of slabs for the swimming pool area (sunken)
3. Bar bending work carried out for the swimming pool slabs
Day 13: 19/06/2014
1. Fresh concreting of columns (the ones that were destroyed when honeycombing was
observed)
2. Curing of the retaining walls (for 10 days atleast)
3. Finished the project report.
4. Returned the safety shoes and the helmet.
7. Apartment Details:
Residential complex. 3 basements + 13 floors (construction of the first basement was going on
during the time of training, 5th
to 19th
June)
Type of foundation : Raft
Excavation depth : 11.05m
Columns : 102 (22 in retaining walls)
Mix design : M40 for columns
M30 for other structural elements
Beams : depth 380-600mm; width 230-300mm
2 leg stirrup. 12,16,20mm dia rods
Columns : 1070x300 mm
6 leg stirrups. 16,20,25mm dia rods
Ramp : for 2 and 4 wheelers. Width – 4.385m
Lifts : 4 lifts
(1.87 m x 1.87 m) – 2
(1.905 m x 2.515 m) – 2
Stairwell : 4.140 m x 2.745 m
Swimming pool : 5.61 m x 10.53 m
Types of labour : Skilled (Carpenters, Barbenders, masons)
Unskilled (coolies; helpers to carpenters and barbenders)
8. ASSIGNMENT: HONEYCOMBING
Honeycombs:
Are hollow spaces and cavities left in concrete mass on surface or inside the concrete mass where concrete
could not reach. These look like honey bees nest.
Honeycombs which are on sides are visible to naked eyes and can be detected easily as soon shuttering is
removed. Honey combs which are inside mass of concrete can only be detected by advanced techniques like
ultrasonic testing etc.
Honeycomb is due to non-reaching of concrete to all places due to which cavities and hollow pockets are
created. Some reasons are:
1) Improper vibration during concrete.
2) Less cover to reinforcement bars
3) Use of very stiff concrete (this can be avoided by controlling water as per slump test).
4) Places like junction of beam to beam to column and to one or more beams are the typical spots where honey
combs are observed. This is due to jumbling of reinforcement of beams and column rods at one place; special
attention is required at such place during concreting and vibrating.
5) Presence of more percentage of bigger size of aggregate in concrete also prevents concrete to fill narrow
spaces between the reinforcement rods.
Treatment:
Strictly speaking wherever honeycombs are observer concrete should be broken and the portion should be re
concreted after applying grouting chemical to the old surface. Honeycombs as a defect not only reduces the load
bearing capacity but water finds an easy way to reinforcement rods and rusting and corrosion starts. Corrosion is
a process which continues through reinforcement rods even in good concrete, this result in loosing grip between
rods and concrete, which is very dangerous to safety and life of concrete structures. R.C.C. structures have failed
with in 20 or 30 years of their construction which is less than half their projected life. Especially no risk should be
taken in case of columns, Machine foundations, Rafts, Beams etc., where breaking and recasting is the only best
way. In case of honey combs on surface pressure grouting with cement based chemicals which are non-
shrinkable can be adopted after taking opinion of the designer and acting as per his advice.
Sometimes, contractors and their supervisors are in the habit of hiding honey combs by applying super facially
cement plaster on the honey combs, hence site engineer must be very cautious.
At places of junction of columns and beams concrete with strictly 20mm and lesser, aggregates should be used
with slightly more water and cement to avoid honeycombs. Tapping the shuttering framework from outs side with
a wooden hammer during concreting and vibrating will help in minimizing honeycombs to a great extent. Use of
thinner needle say 25mm or less with vibrator at intricate places of concreting will also help in reducing honey
combs.
