STAGES OF CONSTRUCTION

LINE OUT OF THE BUILDING

Correct line out & building setting are two important & basic requirements of starting any project

successfully.

Mistakes in line-out can cause considerable losses, leading to demolition of certain parts of the

structures. Line out should always be cross-checked by higher authorities.

STEPS INVOLVED IN LINE-OUT & BUILDING SETTING:-

Cleaning the site & leveling it with minor cutting or filling.

First decided north direction with use of drawing.

Demarcation of the plot & marking actual boundaries with the help of the theodolite survey.

Proposed layout to be marked in the actual demarcation drawings & checked the feasibility of

accommodation at site.

Finalization of all levels with reference to a fixed bench mark.

Checking & approval of all drawings with concerned authorities.

To start the boundary wall construction.

To start preliminary line-out building & other structures & check required dimension.

After confirmation, start a detail line out of project at the site for all the buildings & all other

structures.

Necessary precautions to be taken while doing line out & building setting.

All the steps need to be study carefully, applying engineering knowledge & skills.

Making of right angle to fixed nails means using 3, 4, 5 triangle for the setting out.

PRECAUTIONS TO BE TAKEN FOR LINE – OUT WORK:-

All vertical wooden post should be fixed properly in concrete.

Top portion of vertical post & railing should be kept at the same level using level tube.

All column numbers marked on the railing should be visible.

Nails should not be disturbed till completion of the plinth beam work.

All work should be certified by the architect.

Railing fixing should be done by 50mm nails.

Nails for column centre should be of 40mm only.

EXCAVATION

Excavation is the preliminary activity of the construction project. It starts from the digging pits

for the building foundations & continues up to the handing over of the project.

Requirements to starts excavation:-

The stability & design of the building depends on the strata on which is rest.

So, a trial pit per 400sq.m.area of the plot should be made.

Trial pit should be of the size 1.2m x 1.2m. the depth depends upon the strata.

During excavation different layers of soil are found.

Following table shows various soils & their respective approximate SBC: -

SR.

NO.

STRATA SAFE BEARING CAPACITY

(TONNES / SQ.M.)

1. Very soft, wet,

Pasty clay

0 to 5

2. Black cotton soil 4 to 10

3. Red soil 10 to 30

4. Shadu soil 20 to 30

5. Loose gravel 15 to 25

6. Murum 25 to 45

7. Soft rock 40 to 90

8. Hard rock > 90

Actual bearing capacities of the strata should be derived by:-

1. Static penetration test (SPT) - for soil & clay

2. Plate bearing test - for murum, rock etc.

There are three types of excavators:

1. With bucket

2. With ripper

3. With breake

FOUNDATION AND FOOTING

Foundations used in building construction are broadly classified as

1. Shallow foundation

2. Deep foundation

SHALLOW FOUNDATION:- A foundation is shallow if its depth is equal to or less than its width. A shallow

foundation is also known as an open foundation, since such foundation is constructed by open

excavation. Hence those foundation, which have depth even greater than its width, but are

constructed by way of open excavation also come under „shallow foundation‟. A shallow

foundation is placed immediately below the lowest part of the super-structure supported by it.

The term footing is commonly used in conjunction with shallow foundations.

From the point of view of design, footings are classified in to Three types:-

1. Spread footing

2. Combined footing or strap footing

3. Mat or raft foundation

1. Spread footing:-

Most common & simplest type of foundations.

Distributes the load or weight over a sufficient area on the foundation bed.

It is rectangular or trapezoidal in shape.

Suitable for shallow depth of foundation having moderate bearing capacity.

Its supports either one wall or one column.

A spread footing may be following types:-

1. Strip footing :- It is spread footing for continuous wall.

2. Pad footing :- It is isolated footing for a column.

2. Combined footing:-

This footing supports more than one column.

It is required for columns at the expansion joints.

For columns on the boundary line of the plot or when footings of two columns overlap each

other.

Combined footing may be rectangular or trapezoidal in shape.

3. Raft foundation or mat:-

It is recommended when safe bearing capacity of soil is low & columns carry heavy load.

It is very useful for strata, where there is possibility of uneven settlement.

Footings of groups of columns or all the columns in the structures are combined to form a raft

foundation.

Recommended for soil which have a higher water table.

Raft foundation consists of thick RCC slab covering the entire area at the bottom.

Thus, raft foundation spreads the load of the building over the whole plan area and reduces the

foundation pressure to a minimum.

DEEP FOUNDATION:-

Deep foundations are those in which the depth of the foundation is very large in comparison to

its width. Deep foundations are not constructed by ordinary methods of open pit excavations.

Deep foundations are of the following types:

1. Pile foundation

2. Pier foundation

3. Caisson or well foundation

STUB COLUMN

Stub columns are those columns, which have less height and situated below plinth in between

footing and plinth beams having extra cover of 40mm.

These columns are below ground, means these columns are filled with earth.

PROCEDURE OF STUB COLUMN :-

The distribution rings are distributed as per the spacing given in schedule and extra covers are

provided at alternate rings.

M.S. plates are fixed with angles and cleats and tightened with yokes and clamps. The yokes are

of wooden section of 50mm x 50mm size.

The cleats are provided at 150 to 200mm distance to avoid gap between adjacent plates and

leaking of slurry from gap.

The yokes are provided all over the height not less than 450mm c/c and tightened with clamps.

Then the whole formwork should be checked with respect to plumb,

At the top, concreting top level has been marked.

A group of column is checked in line at the top, with respect to centre line plan & with the help

of string.

Then the columns are casted with the given mix.

Proper curing has to be done.

CONCRETING OF STUB COLUMN:

Surface should be roughened in the position of column for better bonding purpose.

Column starter is fixed with the help of wooden plywood box as per the size of the column and

placed on the footing top.

For marking the perfect position of the column take the help of centre line plan.

Give the extra cover for column.

Check the diagonals of the column.

To check the distances in between the columns as per the center line drawing.

One ring is provided at the bottom to tie the bars in perfect position as per the drawing.

Then the box is firmed position with the help of wedges.

The column starter is casted with the same mix of columns and compacted well with the help of

vibrator.

PLINTH BEAM

Plinth beams are beams constructed or cast for tied purpose. The main purposes of the beams are

tying of columns with each other and now a day these are concreted for earthquake safe design

purpose. Plinth beams having extra cover of 40mm.

Many times position of plinth beam is inside the footing only. Dowels are left as per

the R.C.C. details.

Some time it is just above the footing, in such cases stub columns are not cast.

PROCEDURE OF PLINTH BEAMS:

Reinforcement of the beams is made as per the R.C.C. drawing, proper tying to be provided.

Diameter of bars, binding of stirrups should be in plumb.

Proper anchorage of bottom & top bars in columns.

Length of continuation of bent bars & extra top bars over supports.

Beam bottom should be as per the drawing only.

Beam sides should be always in plumb and line from inside.

The beam side should not be overlapped at beam bottom by more than 50mm.

Concreting top should be marked on the side plank of the footing.

Gaps in bottom sides should be filled.

CONCRETING OF PLINTH BEAMS:

To check the quality of material.

To check the proportion for the required design and mixing for the material with the help of

mixer only.

To ensure that cube moulds are kept ready in position with all requirements.

Control the water-cement ratio.

To check in all joints that no slurry flows from anywhere.

To check the required concrete level.

Compaction should be done properly with the help of needle vibrator.

Curing can be done by watering and with covering jute bags (Hessian cloth)

PLINTH PROTECTION:-

To protect the plinth from this atmospheric action, a path way about

0.6 m to 0.9m wide is constructed throughout the periphery of the building.

The pathway is kept 150mm above the existing ground level.

COLUMN

R.C.C. Column is the vertical structural member in compression, which carries an axial load

coming from beams and slabs & transfer it to the foundation & ultimately to the soil.

The various constructional activities related to the column area as follow :

Casting of starter

Reinforcement of column

Formwork of column

Concreting of column

Stripping work

Curing work of column

STARTER OF COLUMN :-

A starter can be defined as a small strip of 100mm or 150mm in height and other dimension

confirming to the column size accurately. A starter is concreted first because of its following

advantages:-

1. It keeps the column at proper centre.

2. The right angle of the column is maintained.

3. It gives proper cover to the steel at the bottom of column.

4. It provides strong grip to the column formwork at the bottom.

CASTING OF COLUMN STARTER:-

Line string is fixed at outer side of slab top and then diagonals are checked as per center line

plan, before starter sides are fixed.

After fixing of starter sides, all the distances are checked and measured according to the center

line plan & column drawings.

Line, right angle & plumb bob are also checked of every individual starter and also

measurements are checked of every column starter according to column size at the respective

floor.

Check proper covering given or not.

REINFORCEMENT OF COLUMN:

Longitudinal reinforcement is tied to columns as per structural drawing details of columns at

that respective floor.

Lap length should be provided to all the longitudinal reinforcement of column.

In my site, Lap length = 1. For M25 = 41 x diameter of bar

2. For M30 = 38 x diameter of bar

After tying of longitudinal, stirrups are tied to columns as per given in structural drawing of

columns. At my site, stirrups are of 10mm diameter provided at 100mm c/c.

Cover blocks are tied up to stirrups at bottom, middle & top position. Clear cover should be

50mm from stirrups of column.

After tying of reinforcement & stirrups, diameter of bars & number of bar as per structural

drawing.

Supports provided for shuttering should rest on firm ground or base. Supporting is done with the

help of props, clamps & joist. Clamps are provided at every 50mm interval.

FORMWORK OF COLUMN:

Proper shuttering oil is applied to the ply surface so that it can be removed easily after casting of

column without any damage.

Shuttering is fixed around the column as per their size given in structural drawing Shuttering ply

should not be bending & it should be free from every defect and good in quality to give proper

finish.

After shuttering is over, plumb of shuttering sides of columns are checked.

The line & right angle of shuttering sides are checked. Diagonals of columns are also checked.

Size of column is also measured

Supports are checked for rigidity & stability. Minimum covers to the reinforcement of columns

are checked.

FORMWORK OF COLUMN

CONCRETING OF COLUMN:

Surface should be roughened in the position of column for better bonding purpose.

Column starter is fixed with the help of wooden plywood box as per the size of the column and

placed on the footing top.

For marking the perfect position of the column take the help of centre line plan.

Give the extra cover for column.

Check the diagonals of the column.

To check the distances in between the columns as per the center line drawing.

One ring is provided at the bottom to tie the bars in perfect position as per the drawing.

Then the box is firmed position with the help of wedges.

The column starter is casted with the same mix of columns and compacted well with the help of

vibrator.

CHECKLIST OF COLUMN:-

The formwork of column is to be removed after 16-24 hours as per given in I.S. 456-2000.

Finish honey combing carefully.

Date of casting & column number to be written on the column.

Hacking of columns 50 numbers in 1s.ft. (500 Nos. in 1sq.m.)

Curing of columns to be done for minimum 14 days, with wet Hessian cloth rapped around

them.

R.C.C. BEAM AND SLAB

R.C.C. beam are horizontal member in tension. The function of beam is to take load coming

from masonry work and the slab resting on it and it transfer it to the column.

R.C.C. slab is plane horizontal member mostly used as roof covering. The function of R.C.C.

slab is to take dead & live load coming on it & transfer it to column.

Now days, R.C.C. structures are cast monolithically, as monolithic construction turns

out much cheaper then precast construction & structural frame also acts a single unit.

FORMWORK FOR BEAMS:-

First the reference level (Datum level) is marked on outer column of building. This level

brought on that column from the same column below the slab by taking height equal to floor to

height.

Reference level at site is 1.5m from slab level. This level is transferred to all columns with the

help of level tube.

Then the distance between the datum level & beam cap is calculated by considering the beam

depth, thickness of plate with battens etc. And this distance is marked on the column above the

reference level.

Then the „beam cap; is fixed on which beam bottom is fixed horizontally between column.

Then the adjustable steel props are provided at 0.60m c/c to support the beam bottom.

Check the level of the beam bottom before providing the beam sides.

After that beam sides are fixed with the help of nails. Yokes are provided at regular intervals to

prevent the bulging of beam.

FORMWORK FOR SLABS:-

After erection and fixing of beam sides slab shuttering is started. For that wooden plank of

desired width is on the edge of side with nail.

Acrow spans and yokes are used for supporting the slab shuttering plate with adjustable steel

props below. These props are perfectly vertical at required spacing minimum 0.60m c/c.

Put chavi of size 0.10m X 0.10m to supports the slab plates or wooden plank. Chavi should be

supported with a straight prop.

After that the gaps between wooden plank is closed by sticking the cello tape on the joints and

gaps in beam column junction is sealed with cotton waste.

After the completion of shuttering of slab a coat of crude oil is applied on whole formwork

surface.

CHECKING THE FORM WORK OF BEAMS AND & SLAB:

The width & depth of beam is checked with measured tape as per beam‟s detail in

R.C.C consultant‟s plan.

The vertically of interior surface of formwork of beam is checked with help of plumb

bob.

Line & level of beam is checked with the help of line string & level tube.

Checking the size & diagonals of each slab spans & thickness of slab.

Checking the level of slab with the help of line string & level tube.

Slab plates should be supported by 75mm x 75mm

REINFORCEMENT OF BEAMS :-

In R.C.C. drawings, the number of bottom bars, bent up bars & top bars along with

details of rings are normally mentioned.

Cutting should be done beam-wise & for the total number of beams, required for slab.

Beam can be bound on fitter‟s platform along with the bent-up bars.

Shift the bound beam to the shuttering of the slab.

Place these beams to the position with proper anchorage in the end columns.

For continuous beams, bent-up bars should be properly extended in the adjacent

beams & tied with binding wires.

Proper cover block of 40mm sizes are provided for the beam reinforcement.

REINFORCEMENT OF SLAB:-

For continuous slab the projection of bent in the adjacent slab is considered while

calculating the cutting length of the slab reinforcement.

The c/c distance of bars is marked on the slab plates with the help of chalk.

Main reinforcement is laid as per marking.

Then the distribution steel placed on main reinforcement and each and every junction

should be tied with binding wire.

The cover blocks of size 25mm for slab reinforcement are provided.

Bent up bars are bend at required length from support depending upon the types of

slab.

Chairs are provided at necessary or required position.

Then the stirrups of beams are tied with main reinforcement according to beam

schedule shown in R.C.C consultant‟s plan.

Then the reinforcement is lowered down in shuttering of beam and proper cover

block of 40mm sizes are provided for the beam reinforcement.

CHECKING THE REINFORCEMENT OF BEAMS & SLAB:

FOR BEAMS:

Number of top bars and number of bottom bars in beam are checked as per R.C.C

plan.

Number of stirrups and spacing between the stirrups is checked as per R.C.C. plan.

Checking of development length is checked.

Checking of cover to reinforcement of beam which is 40mm for beam.

Extra stirrups at the junction of beam.

FOR SLAB:

The number of main reinforcement bars and its diameter is checked as per R.C.C

consultant‟s plan.

Distribution bars and spacing between it is also checked.

Length & height of bent up bars projecting in the adjacent panel.

Chair below every bent up bar should be checked.

Proper binding of laps of the required length.

Covering for the slab at bottom.

Put stirrups in the column for upper floor columns.

Also checking of dowels bar for staircase etc.

MANAGEMENT FOR CASTING SLAB & BEAM :-

The formwork & reinforcement of beams & slab is checked by R.C.C. consultant one day

advance before casting & any remarks suggest by him is get rectified immediately.

Arrangement of materials like cement, sand, metal-1, metal-2 for casting of slab in

well advance or ordered in RMC plant.

Arrangement of water, in case of electric failure & labour strength.

The concrete mixer, Vibrators, skip and hoist machine is well cleaned by oiling and

the working of that machinery is done by taking trial so there is no delay in work due

to equipments faults.

The slab and beam is well cleaned with water and dust, wooden pieces and solid

waste is remaining.

The arrangement of 12nos of cube moulds is done for casting the cube moulds.

On my site slab is casted in two parts therefore it is necessary to decide the position

of construction joints.

CONCRETING OF BEAMS & SLAB:

First the concreting level is marked on side planks by means of nail as the

thickness of slab.

Then neat cement slurry is poured at the junction of beam to column.

Then the actual process of concreting is started. The concrete is placed in beam first

and then place on the slab span

The compaction is done by the needle vibrator simultaneously. A 40mm needle

vibrator is used for the compaction in beam concreting and 60mm & 40mm both

vibrators are used for the compaction of slab concreting.

After compaction of one span the mason start leveling with the help of big wooden

float before leveling with the entire portion is further compacted with the thick

wooden tamper.

After leveling the surface is roughened with finish so as to receive the bedding

materials of flooring.

While the concreting of next part of slab this construction joint is hacked and neat

cement paste is applied and the placing of concrete is continued further.

The care taken while concreting of beam and is that is no interruptions or breaks as

far as possible.

CURING OF BEAMS & SLAB:

Curing of slab was done using the method of ponding by forming continuous panels

containing water bounded by small mortar bunds. A minimum 14 days of curing is done to the

slab. This curing pond is known as „wata‟.

DESHUTTERING OF BEAMS & SLAB:

AS per R.C.C consultant‟s the Deshuttering of beams & slab is given in following table

Sr. No DESCRIPTION PERIOD

(1) Outer sides of beams After 24 to 48 hrs. Of casting.

(2) Removal of props to slabs :-

(a) Spanning up to 4.5m After 7 Days of casting.

(b) Spanning over 4.5m After 14 Days of casting

(3) Removal of props to beam :-

(a) Spanning up to 6m After 14 Days of casting

(b) Spanning over 6m. After 21 Days of casting.

STAIRCASE

The staircase may be defined as the series of steps arranged for the purpose of transportation of

materials and persons within a building. Staircase provided was doglegged staircase. The waist

slab was 1.5m wide. The load from the steps is transferred onto the waist slab & from there onto

the beam and the mid-landing, which rests on the column. The floor-to-floor height was 3.0m &

the staircase consisted of two flights. The tread size was 250mm & the riser was of 161mm size.

SHUTTERING OF STAIRCASE:

The mid landing shuttering was done first with the levels of the M.L checked.

Waist slab is erected in between beam & the mid-landing.

The slope for the waist slab was given according to the levels.

The thickness of the waist slab was then checked.

The dimensions of the mid-landing are checked.

The risers are then fitted according to the levels.

The size & plumb of the risers is checked.

The supporting for the waist slab & mid-landing is checked.

REINFORCEMENT OF STAIRCASE:

Check reinforcement of staircase according to the R.C.C. plan.

The side, bottom & top cover are checked.

The development length of the bars is checked.

Chairs for reinforcement are provided.

BRICK MASONRY

Brick masonry is made of brick units bonded together with mortar.

Bricks are manufactured by molding clay in rectangular blocks of uniform predetermined size,

drying them & then burning them in kiln.

Normally, 100mm thick brickwork is done for partition walls & 150mm thick for external walls.

The strength of brick masonry depends upon:-

1. Quality of bricks

2. Quality of mortar

3. Method of bonding used.

Tools used for construction of brick masonry are:

Trowel.

Mortar pans

Plumb bob.

Spirit level.

Tri-square.

Line and pins.

Brick hammer.

Bonds in brick work:-

It is the method of arranging bricks in courses, so that individual units are joined &

vertical joints of successive courses do not lie in the same vertical line.

Bonds are various types are distinguished by the elevation or face appearance. Bonds

help in distributing the concentrated loads over a larger area.

LAYOUT OF BRICK WORK:-

PROCEDURE:-

The bricks are immersed in water for at least half an hour, but it should be dry at the time of use.

Hacking is done to the concrete surface, which is in contact with any masonry.

Watering clears the slab top.

Cement mortar is laid on the surface (C: M = 1:4 in proportion for 100mm thick brickwork & C:

M = 1:6 for 150mm thick brickwork.)

Line out of a single bricklayer is done as per the architectural drawing.

The brickwork is started with the entire horizontal, which is in exact plumb & true plane.

The joints between the bricks are not more than 10 to 15 mm thickness.

The bricks are always laid in frog impression upwards.

Excess mortar shall be removed.

Types of bond in brick work:-

1. Header bond.

2. Stretcher bond.

3. English bond.

4. Flemish bond.

STRETCHER BOND:-

This type of bond is used for half brick thick wall (100mm). In this type of bond, all the bricks

are laid with their lengths in the wall direction & the frog impression upwards. Such as those

used as partition walls, sleeper walls, division walls & chimney stacks. This wall is not possible

if thickness of the wall is more.

FLEMISH BOND:-

This type of bond is used for one brick or thicker brick wall. In this type alternate headers &

stretchers are laid on each course. The queen closer is placed next to

the quoin header, in order to break continuity of the vertical joints, for firm bond. This type of

bond is better in appearance.

Curing:-

The brick work should be well watered for period of 7 days.

COMPARISON BETWEEN ENGLISH BOND & FLEMISH BOND

SR.NO. ENGLISH BOND FLEMISH BOND

1. This bond is stronger. This bond is not stronger as

English bond.

2. No pleasing appearance. Give pleasing appearance.

3. Broken brick can not be used. Broken brick can be used.

4. Semi skilled labour can construct

this bond.

Skilled labour required.

STIFFENER:-

Above 1m of brick masonry, stiffener (patli) was casted at the grade of M 15(1:2:4) to increase

strength of brick wall.

PLASTER MASONRY

Plastering is the process of covering the masonry & concrete surface with

mortar to obtain a smooth, even & sound surface. Plaster is the layer of cement-sand mortar

applied over masonry work, which also act a damp-proof coat over the masonry work.

Objects of plastering:-

To protect the surfaces from atmospheric influences.

To cover the defective workmanship in masonry.

To cover up unsound & porous material.

To provide a suitable base for color wash/paint.

Material used:-

1. cement 3. water

2. sand 4. admixtures

Tools required for plastering:-

1. mortar pans 6. measuring tape

2. spade 7. plumb bob

3. trowel 8. right angle

4. wooden floot 9. aluminum hollow box section

5. nylon string 10. batten for making groves

INTERNAL PLASTERING :-

Procedure

The plaster works shall be taken up below the floors on which masonry has been completed and

no vibrations due to any activities are anticipated.

The plastering surfaces shall be well scored to form properly and kept wet for two days.

The mason shall check the plumb of door/window frame, by a plumb bob, before starting the

plastering work. All hackings (skin removal 3 mm deep) on concrete surfaces shall be checked

for adequacy – mechanical key. The spackling shall not be more than 25 to 30 mm apart as per

approved sample.

Hack Aid chemical shall be sprayed / brushed with hand pump on concrete surfaces with prior

permission. It shall be ensured that drops of hack aid fallen on the chromotized Aluminum sub

frame are cleaned immediately.

All the joints of masonry & R.C.C. secured by fixing chicken mesh to avoid cracking 7

leakages in future.

A dash coat shall be applied within few minutes of applying hack aid and left rough.

Subsequently after proper curing, finishing coat shall be done the day after.

The cement mortar used for plastering shall be mixed in steel trays in the proportion of (1:4) by

volume for walls or ceilings. Sprinkling dry cement on plastered surface to be strictly avoided.

Cement shall be OPC 43 grade or PPC.

Mix only 2-3 bags depots at time & use mixed depots within half an hour.

The internal plastering shall be done in a single coat of 12 mm thick for walls and 10 mm thick

for ceilings.

On the second day, smooth finishing should be done with the mason trowel, before starting the

day work.

Check the diagonals, right angles of all walls & window jam.

Do not carry out the plastering of bottom 30cm portion in W.C. & bath from slab level.

As no skirting is to be provided below & to the sides of the kitchen otta & balcony, plaster all

the four walls up to 25mm from the bottom slab level.

EXTERNAL PLASTER:-

Procedure

Double scaffolding shall preferably used with prior authorization of its stability

from the structural Engineer. All safety precautions during the plaster works shall be taken.

The plastering surfaces shall be well scored to form mechanical keys and kept wet for two days.

The areas to be plastered may be covered from wind and sun to prevent fast setting.

External plaster is started from top & worked down towards floor.

All hacking of concrete surfaces shall be checked and necessary additional hackings if required

shall be carried out. (Spacing generally not >25 to 30mm apart and skin removed about 3mm

deep).

In addition Hack Aid Chemical shall be sprayed with hand pump/brushed on concrete surface

with prior permission.

All plumbing/Fire/Electrical and other service openings shall be properly closed.

External plastering shall be done in two coats.

Cement mortar mixed in steel trays/machine mixed and of proportion 1:4 shall be used for first

(single) coat and 1:3 for second (double) coat. PPC cement or OPC 43 grade cement shall be

used for plastering.

The first coat shall be 12 to 15 mm thick, key formed in the first coat, to receive the finishing

coat. The surface of this first coat shall be cured for 3 days. Drip mould shall be made of

adequate depth and width wherever necessary as per architect‟s approval. Similarly,

bands/grooves shall be provided on blank walls with no elevation features to avoid

shrinkage/expansion/contraction cracks due to large surface area.

The finishing coat shall be applied after four days of application of the first coat. This coat shall

be applied in a uniform thickness of 6 to 8 mm. The surface shall be dabbed to have uniform

grained texture by using sponge pads.

Curing shall be ensured for 7 days.

DEFECTS IN PLASTERING:-

1. BLISTERING OF PLASTERED SURFACE:-

The small patched swell our beyond plane of the plastered surface & this defect is

particularly seen in case of plastered surface inside the building.

2. CRACKS:-

These are formed on plaster surface & may be hair cracks or cracks which may be easily

seen the development of fine hair cracks is known as crazing.

Reason:-a) movement of background

b) shrinkage movement of plastering mixes

c) excessive toweling

d) varying thermal expansion

3. EFFLORESCENCE:-

The soluble salts are present in plaster making materials as well as building materials

such as bricks, sand, cement etc. even water used in construction work may contain soluble salts.

When a new constructed wall dries out, the soluble salts are brought to the surface & they appear

in the form of whitish crystalline substances. Such a growth is referred to as the efflorescence 7 it

seriously affects the adhesion of paint with wall surface.

4. FLAKING:-

The formation of a very small loose mass on the plastered surface is known as the

flaking & it is mainly due to bond failure between successive coats of plaster.

5. PEELING:-

This is due to bond failure between ceiling concrete & coat of plaster. Care to be taken

by closely hacking 500Nos/m³ & cleaning the ceiling for making it free from oily substances.

6. POPPING:-

Sometimes the plaster mixed contains particles which expand on being set. A conical hole

in plastered surface is formed in front of particles. This conical hole is known as the bolw or pop.

7. UNEVEN SURFACE:-

This defect becomes prominent only due to poor workmanship of the work.

8. SOFTNESS:-

The excessive dampness at certain points on the plastered surface makes that portion soft.

The chief reason of such softness are undue thinness of the finishing coat, presence of

deliquescent salts, excessive suction of the undercoat etc.

PLASTER OF PARIS

Plaster of Paris is the special material used in the finishing coat of plastering. When finely

ground gypsum rock is heated to a temperature between 100ºc & 140ºc three-fourth of the

combined water process off as steam. The remaining product is known as “Plaster of Paris”.

At my site, it was used in internal plasters. Plaster of Paris is used ornamental plaster works

& it is very valuable for this purpose. It produce hard surface, sharp contours & its sufficient

strong.

PROCEDURE:-

When water is added to Plaster of Paris it hardened in 3 to 4 minutes which is to short time for

operator to used it for plastering.

Hence, only a small quantity of plaster of paris is mixed at a time & which is consumed

immediately after mixing.

A mixed plaster of paris is taken on a aluminum plate using trowel. Then this plaster of paris

rubbed upon the prepared surface using aluminum plate.

Plaster of Paris does not required any curing.

GENERAL R.C.C.

3.1 FORMWORK

The temporary structure erected to support the concrete in its required shape, till it hardens &

becomes self supporting is known as the “formwork or shuttering”.

In the type of formwork, the material could be steel plate, plywood wooden plank or wooden

prop.

REQUIREMENTS:-

A good formwork should satisfy the following requirements:-

The material of the formwork should be cheap & it should be suitable for re-use several times.

It should be practically water proof so that it does not absorb water from concrete, also its

shrinkage & swelling should be minimum.

It should be strong enough to withstand all loads coming on it, such a dead load of concrete &

live load during its pouring, compaction & curing. It should be stiff enough so that deflection

is minimum.

It should be as light as possible.

The surface of the formwork should be smooth & it should afford easy stripping

All joints of the formwork should be stiff so that lateral deformation under load is minimum, also

these joints should be leak proof.

The formwork should rest on non-yielding supports.

STRIPPING PERIOD OF R.C.C MEMBERS:

1. Walls, columns and vertical faces of

structural members

24 Hours

2. Slabs (Props left under)

Thickness more than 150mm

07 Days

3. Beam soffits

(Props left under)

10 Days

4. Removal of props under slab

Spanning up to 2.5m

10 Days

5. Removal of props under beams

Spanning up to 5.0m

15 Days

Spanning over 5.0m 21 to 28 Days

Forms shall not remove before the concrete is set. The operation of removing the

formwork is commonly known as „stripping‟.

The following is the chart that is commonly referred for knowing the period of

removal of formwork.

LOADS COMING ON FORMWORK:-

Live load due to labour.

Dead weight of wet concrete.

Hydrostatic pressure of the fluid concrete acting against the vertical or inclined faces of form

Impact due to pouring concrete.

FORMWORK MATERIALS AT SITE

1. Centering Plates:

Theses M.S. Plates are used for the slab form work. These M.S. plates are available in

various sizes such as 90cm x 60cm x 2.5cm, 120cm x 60cm x 2.5cm, 45cm x 90cm x 2.5cm etc.

Mostly 90cm x 60cm x 2.5cm was used for slab.

2. Plywood Planks:

The plywood planks are used as columns formwork, beams formwork, beam bottom etc.

these are cutter or made according to sizes of columns and beams. The size of plywood is 1.20m

x 2.40m and thickness of plywood is generally about 10 to 12mm.

3. Acrow span:

Theses spans are used to support the centering plates for shuttering of slab. This can be

adjusted for any length between 2.0m to 4.0m.

4. Adjustable Steel Props:

The props used for steel formwork are specially made to adjust the height of the prop as per

the requirement. These props can be used to accommodate the variations in the height of beams,

slab and all R.C.C members. Size of props = 2.10m (When not opened) and 3.60m (when

opened).

5. Adjustable clamps (Shikanja):

Theses adjustable clamps are used to tight the shuttering by clamping to avoid the bulging

out of formwork during concreting due to concrete pressure.

3.2 REINFORCEMENT

Concrete is a solid mass which is very good in compaction but weak in tension. It cannot

take up tensile stresses induced on it, where as steel is very strong in tension. Combination of

such concrete & steel can take up both tensile as well as compressive stresses. This combination

of concrete & steel is called “Reinforced Cement Concrete” popularly known as R.C.C.

The various diameters of steel used at my site were 8mm, 10mm, 12mm, 16mm,

20mm, 25mm.The steel used were TMT steel.

There are two common types of reinforcing bars:-

Mild steel bars C.T.D. ( cold twisted deformed)

High yield stress deformed bars (H.Y.S.D.)

LAP LENGTH OF STEEL:-

When bars of insufficient length are to be extended to the required length, than a certain

amount of lap length is to be kept to transfer the stress from one bar to another. As far as

possible, lapping should be done at the point of maximum stress. The two bars were lapped to

each other with the help of binding wire. At our site the lap length was kept generally as per the

standard formula i.e.50d for vertical reinforcement & 58d for horizontal reinforcement, where d

represents the diameter of the reinforcement bar.

Cover for Reinforcement:

Covers are the most important part of the reinforcement since they prevent the contact of the

reinforcement with the formwork & thereby also prevent honeycombing.

This enables the concrete structure to have a smooth texture. At our site cover for

reinforcement was maintained by using precast cover blocks, which were made by cement, sand

& water.

They were prepared in wooden moulds. In slabs, chairs were used to maintain to the clear

distance in between the top & the bottom bars.

At our site, cover provided for different structural members was as follows:

MEMBERS COVER PROVIDED

SLAB 20mm

BEAM 30mm

COLUMN 40mm

STAIRCASE 20mm

WEIGHTS OF STEEL OF DIFFERENT DIAMETERS:

The weight of steel bar per meter length is calculated using the formula:

Weight of steel = (diameter) 2

162

These weights were calculated for taking out the quantity of steel required for a structure to

be constructed. Hence they have to be properly calculated & remembered.

Following are the weights for different diameters of steel:

Diameter of bars

(mm)

Weight of the bar per

meter length (kg)

8 0.395

10 0.617

12 0.889

16 1.580

20 2.469

25 3.858

32 6.320

BAR BENDING SCHEDULE:-

The schedule bars is list of reinforcement bars in a tabular form giving a

particulars of bars, shapes of bending with sketches, length of each bars, total length & total

weight of each type. Form the schedule bars the requirement of different sizes & length s of bars

may be known & thus can be arranged & bent up during the time of construction from the

schedule of bars the weight of steel required for particular work like slab, beam, column, footing,

etc. can be calculated.

BAR BENDING SCHEDULE:-

CONCRETING

Concrete is mixture of cement, coarse aggregates, fine aggregate & water. Concrete is a

freshly mixed material, which can be molded in any shape. The proportion of these ingredients

SITE : PAGE NO:

DATE: BILL NO:

ITEM

NO.

PARTICULARS NO. LENGTH 8 10 12 16 25

TOTAL

depends upon the grade of mix (M 10, M 15, M 20, M 25, M 30, M 35, M 40 etc.) required for

meeting the requirements of a particular job. In concrete, the hard inorganic materials such as

sand, crushed stone are bounded together with the paste of cement & water.

When the materials are mixed together, they form a workable mixture which can be

molded as any structural member before its hardening & after setting, it hardens & attains greater

strength; & such a concrete is known as plain cement concrete.

When any steel is used as reinforcement in concrete mass to resist the tension, it is known

as reinforced cement concrete or R.C.C.

Procedure for preparation of concrete on which the quality of concrete

depends:

a. Batching.

b. Mixing.

c. Transporting.

d. Placing.

e. Compacting.

f. Finishing.

g. Curing,

BATCHING:-

The measurement of materials for making concrete is known as batching.

There are two methods of batching:

a.

Volume batching is not a good method for proportioning the material because of

difficulty it offers to measure granular material in terms of volume. Volume of moist sand in a

loose condition weighs much less than the same volume of dry compacted sand. The batching is

done with the help of M.S. gauge boxes. The size of box is 29cm (length) x 35cm (height) &

width is as per the volume box; means the box having 35cm in width will have 0.035m3 volume.

MIXING:-

The aggregates, cement & water should get thoroughly mixed so as to get uniform

strength in the mass concrete.

Hand mixing can be done for the small amount of work. But in case of major amount of work

hand mixing should not be used. In such cases machine mixing can be done. The mixing is done

by concrete mixer. It has rotating drum around its inclined axis; consisting of its blades for

mixing concrete. It is an efficient & economical method for mixing concrete as quality can be

maintained.

Mixing time:-

Concrete mixer is generally designed to run at a speed of 15 to 20 revolutions per minute.

For proper mixing, it is seen that about 25 to 30 revolutions are required in a well designed

mixer.

TRANSPORTING:-

After mixing, the concrete has to be transported, where placing is to be done.

Carrying concrete from the place of mixing to the place of delivery is known as transportation of

concrete. Concrete can be transported using various methods & equipments. While transporting

concrete, ensure that the homogeneity obtained at the time of mixing is maintained during

transportation.

The methods adopted for transportation of concrete are:

Mortar pans:-

Using mortar pan is the most common practice adopted all over the country. This method

can be conveniently used for concreting of small & medium size project.

Wheel-barrow:-

This method is employed for hauling concrete over comparatively longer distances. The

capacity of bucket should preferably be in multiples of a batch of concrete. Wheel barrows are

also suitable for short & flat hauls for all types of construction projects.

Crane, Bucket & rope way:-

A crane & bucket is one of the right equipment for transporting concrete above ground

level. This method is used for difficult & odd works, such as concreting in a valley, construction

work of a pier on a river or for dam construction.

Chute arrangement:-

Chutes provided for transporting from ground level to lower level. The layout is made

in such a way that the concrete will slide evenly in compact mass without any separation or

segregation. This is not good method of transporting concreting.

Transit mixer :-

It is most popular equipment. They are truck mounted having a capacity of 4 to 7

m³.transit mixing permits longer haul & is less vulnerable in case of delay. The speed of rotating

of drum is between 4-16 revolution per minute. Restrict the time of 2 hours during which cement

& moist sand are to remain a contact.

PLACING:-

It is not enough that a concrete mix correctly designed, batched, mixed & transported; it is

of utmost importance that the concrete must be placed in systematic manner to yield optimum

results.

Following precautions are to be taken while concreting:

The formwork or other surface where concrete is to be placed should be properly cleaned &

well watered.

Large quantity of concrete should not be deposited at a time.

Concrete should not drop from the height exceeding 1.5m. It may cause segregation of

aggregates.

Avoid cold joints in successive layers.

Placing concrete under water.

COMPACTION:

Compaction of concrete is the process adopted for expelling the entrapped air from the

concrete. In the process of mixing, transporting and placing of concrete air is likely to get

entrapped in the concrete. The lower the workability, higher is the amount of air entrapped. In

another words, stiff concrete mix has high percentage of entrapped air and, therefore, would need

higher compacting efforts than high workable mixes. The entrapped air, if not removed

completely, considerably reduces the strength of concrete. Generally 5% voids reduce the

strength of concrete by about 30% & 10% voids reduce the strength by over 50%.

The following methods are adopted for compacting the concrete:

1. Hand Compaction:-

a. Roding

b. Ramming

c. Tamping

2. By vibration:-

a. Needle vibrator.

b. Table vibrator.

c. Platform vibrator.

d. Surface vibrator.

e. External vibrator.

We are using needle vibrator of 40mm & 60mm diameter sizes as per requirement.

Needle vibrator:-

Of all vibrators, the internal vibrator is most commonly used. This is also called as

„internal vibrator‟, „immersion vibrator‟ or „poker vibrator‟. The vibrator used on the site was

immersion vibrator. This essentially consists of power unit, a flexible shaft & needle. The power

unit may be electrically driven or operated by petrol engine or air compressor. This needle is of

detachable type & its diameter varies from 20-75mm & its length varies 25-90cm. The frequency

of vibration varies upto 12000 cycles of vibration per minute.

The needle vibrator helps on removing the entrapped air & voids & thereby compacting

the concrete to form in seconds. Vibrator should not touch the formwork & it should not be used

for pushing the concrete.

3. Compaction by pressure & jolting:-

This is one of effective method of compaction. This method is used for compacting

hollow block, cavity block & solid concrete block.

4. Compacting by spinning:-

This is one of the recent method of compaction. This is adopted for the fabrication of

concrete pipe.

FINISHING:

Finishing operation is the last operation in making concrete. Finishing in real sense

does not apply to all concrete operations. For a beam concreting may not be applicable, whereas

for the concrete road pavement, airfield pavement or for the flooring of a domestic building,

careful finishing is of great importance. Concrete is often dubbed as a drab material, incapable of

offering pleasant architectural appearance and finish.

The following methods are adopted for finishing:

a. Formwork finishes

b. Surface treatment

c. Applied finishes

CURING:

Curing can be defined as keeping the concrete moist & warm enough, so that hydration of

cement can continue. It is the process of maintaining satisfactory

moisture content & a favorable temperature of concrete, during the period immediately after

placing, so that hydration of cement continuous until the desired properties develops to the

required degree.

METHODS OF CURING:

1. Water curing

2. Membrane curing

3. Application of heat

4. Miscellaneous

1. WATER CURING:-

This is the best method for curing. Water curing can be done in the following ways:-

a. IMMERSION:- The precast concrete items are normally immersed in curing tanks for the

required duration.

b. PONDING :- Floor slabs, road slabs etc. are covered by water by making small ponds of

water.

c. SPRAYING & WET COVERING :-

Vertical retaining walls & concrete columns are cured by spraying water. In some cases, wet

covering such as wet gunny bags, Hessian cloths are wrapped around vertical surfaces for

keeping concrete wet

2. MEMBRANE CURING:-

During actual shortage of water, it is not possible to cured the concrete with ample

quantity of water. In such cases membrane curing is done.

3. APPLICATION OF HEAT:-

When concrete is subjected to higher temperatures along with moisture, it accelerates the

hydration process, resulting in the development of strength.

4. MISCELLANEOUS METHODS:-

Applying calcium chloride on the surface of the concrete member is useful for

effective curing. Calcium chloride is a salt & shows affinity for atmospheric moisture retaining it

at the surface.