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Specification and Estimation
Lecture: 5
Basic information necessary to write specification for differentItems ofWork (Making of a Building)
Items of Work Materials Proportioning Workmanship Testing
Earthwork in
excavation of
Foundation Trenches
Clear site of grass, roots of trees and other organic matter
Dimensions of the excavation as shown in drawings or as decided by
Engineer in charge
Side of the trenches vertical and bottom level both longitudinally and
transversely
Bottom of trenches to be sprinkled with water and rammed
Excess digging to be filled with concreteAll excavated material to be kept at least 1 m away from the trenches
All existing pipes, cables, sewers etc. to be temporarily shored
All valuables and materials found during exaction to be the property of the
Government
The cost of all materials and labour required for fencing in and protection
against risk of accidents are born by the contractor
Earthwork In Filling Earth used for filling to be
loose, free from brick bats,
stone and boulders not larger
than 75 mm in any direction,
salts, organic or other foreign
matter
The filling to be done in layers not exceeding 20 cm each layer.
Each layer to be watered, rammed before the next layer is laid
Earth to be rammed with iron hammers where feasible or crowbars
In case of filling under floors, the finished level of filling to be in slope as
intended in the laying of the floor
Sand Filling in Plinth Sand used in filling to be fine,
free from dust, organic and
foreign material
Sand to be spread in layers not exceeding 20 cm and to be saturated with
water
Ramming will be through a number of hammers where the distance between
two hammers not to exceed 1.5 m.
Successive course of ramming to be in transverse direction
Before ramming the final layer, the entire filled up area is flooded with water
Final filled surface to be leveled in both directions to the desired slope.
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Brick Soling in
Foundation Trenches
Picked Jhama or 2nd
class bricks
in dry condition to be used
Bricks are used as headers with frog upwards
Bricks to be laid breaking joints and small gap between them to be filled with
local fine sand or dry loose earth
Brick bats used to break joints to be placed at the edges of trenches
The finished surface to be leveled in both directions(longitudinally as well as transversely)
Lime concrete in
trenches
Coarse aggregate from breaking
good quality over-burnt or well
burnt dense brick bats small
enough to pass through 32 mm
dia ring
Fine aggregate to be surkhi or
cinder(preferably surkhi) made
from well burnt first class
bricks bats grounded small
enough to pass through I.Ssieve of 4.75 mm
Lime to be freshly burnt, slaked
and free from ashes and
screened through a sieve of 3
meshes to a cm. The slaking of
lime is done at site unless
otherwise specified
Coarse
aggregate,
surkhi and lime
proportion to
be 100:36:18
The mixing to be done by hand or mechanical mixer.
Hand mixing to be done on clean solid water-tight masonry platform
Brick ballast to be soaked in clear water for at least 2 hours before mixing and
stacked evenly on a platform in maximum height of 30 cm
Lime and surkhi to be measured with wooden boxes measuring generally 35
cm x 25 cm x 40 cm and mixed dry till of uniform colour and spread over
stacked ballast
The whole mixture to be turned over once without adding water and further
three times gradually adding water so that the whole surface of the ballast
becomes coated with mortar and the mix becomes plastic enough to giveuniform concrete
The volume of concrete to be limited to what has to be used in 1 day
Old and stale concrete not to be used
Concrete to be laid (not thrown) in courses not more than 20 cm thick at a
time and consolidated until the layer is 15 cm thick
Weight of the compacting hammer not to be less than 4.5 kg and area not
more than 300 sq cm.
Consolidation to be completed only till a skin of pure mortar covers the
surface
In hot season lime water to be sprinkled regularly during ramming to keep the
concrete wet
No ramming to be done on the next day when the mortar has started settingGreen work to be protected from rain by suitable covering
Where joints in layer are unavoidable, the end of each layer to be sloped off
to an angle of 30 degrees
Concrete to be kept moist with gunny bags, sand for at least 7 days and no
masonry to be laid on the lime concrete bed within this period
Two days
after
ramming, the
concrete to
be tested by
digging a
hole about
7.5 cm deep
and 7.5 cm in
dia. Andfilled with
water
In this test,
the water
level does
not go down
The safe
compressive
strength of
lime concrete
is taken as 43
tonnes / sqm.
Cement Concrete Coarse aggregate is crushed or
broken from hard stone
Cement
1
Mixing:
Hand Mixing: Hand mixing is permitted only for small works but normally
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obtained from hard stone. It is
hard, strong, dense and durable,
clean and free from soft friable,
thin, flat, elongated or
laminated, flaky pieces and isroughly cubical in shape. It is
free from dust and any other
foreign matter. It can be gravel
or river bed shingles or pit
gravel. The size of the coarseaggregate is 20 mm graded
down and retained in 5 mm
square mesh so that the voids
do not exceed 42 %. For road or
mass concrete work, bigger size
of 40 to 60 mm is prescribed.
Fine aggregate is usually
coarse sand able to pass
through IS sieve of 4.75 mm.
Sea sand is not used. Sand is
free from dirt and organic
matter. Crushed dust stone may
also be used as fine aggregate.
Cement is fresh Portland
cement conforming to IS: 269.
Quantity of water:The quantity
of water to be used for each mixof 50 Kg cement to give the
required consistency is not
more than 34 litres for 1:3:6
mix, 30 litres for 1:2:4 mix, 27
litres for 1: 11/2 : 3 mix and 25
litres for 1:1:2 mix.
In the case of vibrated concrete,
the limit specified may be
Fine aggregate
2
Coarse
aggregate 4
i.e. 1:2:4
Measured by
measuring
boxes 30 cm x
30 cm x 38 cm
The above is
equivalent to 1
bag of cement
of 1/30 cum or
.035 cum.
Cement ismeasured by
bag weighing
50 kg when
dry.
While
measuring
aggregate,
shaking,
ramming or
hammering is
not permitted.
all structural concrete is mixed in a mixer machine.
The mixing is done on a clean watertight masonry or concrete slab or steel
plate platform.
Measured quantity of sand is spread evenly after which the cement is dumped
on the sand and distributed evenly.The cement and sand are then mixed thoroughly with spade turning the mixer
again and again until it is of even colour throughout and is free from streaks.
The measured quantity of coarse aggregate is then spread out and the sand
cement mixture is spread on its top or a reverse operation is done.
The complete mixer is then turned at least three times by shoveling and
turning over by twist from center to side and then back to the centre and
again to the sides.
A hollow is made in the centre of the pile of the mixed pile and three quarters
of the water required is added while the mixture is turned towards the centre
with spades.
The remaining water is added by a water can fitted with rose head, slowly
turning the over and over again until a uniform texture and consistency isobtained.
The mixing platform is washed at the end of the day.
Machine mixing: The mixer drum is flushed clean with water. Measured
quantity of dry coarse aggregate is placed first in the hopper.
This are followed with measured quantity of fine aggregate and then cement.
In case, damp sand is used, add half of the quantity of coarse aggregate.
The dry materials are mixed in the mixing drum for at least four turns of the
drum, after which the correct quantity of water is added gradually while the
drum is in motion, to ensure even distribution with the dry materials.
The total quantity of water for mixing is introduced before 25 percent of the
mixing time has elapsed and is regulated to achieve the specific water cement
ratio.
The mixing is thorough to have a plastic mix of uniform colour.
The complete contents of the mixed concrete are emptied before recharging.
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suitably reduced to avoid
segregation.
The quantity of water is
regulated by carrying out
regular slump tests.
When the mixer is closed down for the day or for any time exceeding 20
minutes, the drum is flushed clean.
Mi xing time: The materials are mixed in a drum for a period of not less than2 minutes and until a uniform colour and consistency are obtained. The time
is counted from the moment all the materials have been put into the drum.
Laying: The entire concrete used in the work is laid gently (not thrown) in
layers not exceeding 15 cm and is thoroughly vibrated by means ofmechanical vibrators till a dense concrete is obtained.
The Engineer-in-Charge may however relax this condition at his discretion
for certain items depending upon the thickness of the members and feasibility
of vibrating the same and permit hand compaction.
Hand compaction is done with the help of punning rods and tamping withwooden tampers so that concrete is thoroughly compacted and completely
worked into the corners of the formwork.
The layers of concrete are so placed so that the bottom layer does not finally
set before the top layer is placed.
Compaction is completed before the initial setting starts i.e. within 30 minutes
of addition of water to the dry mixture.
During cold weather casting of concrete is not done when the temperature
falls below 4.50C. During hot weather precautions are taken to see that the
temperature of wet concrete does not exceed 380C. Concrete is not allowed tobe deposited under water.
Where found necessary to deposit any concrete under water, the method and
equipment is first approved by the Engineer-in-Charge.
Concrete is deposited continuously until it is brought to required height;
while depositing, the top surface is kept as nearly level as possible and the
formation of seams are avoided.
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The concrete is deposited under water by one of the approved methods such
as Treamic Method. Drop and bottom bucket, bags etc.
When the placing of concrete is suspended, or resumed on the following day,necessary roughening of the surface for joining future work is done before the
concrete sets. When the work is resumed the previous work must be
thoroughly cleaned, roughened, watered and a grout of neat cement slurry of
the proportion, I kg of cement per 2 litres of water applied uniformly.
Protection and curing: Freshly laid concrete is protected from rain by
suitable covering. The work should also be protected from damage and rain
during construction. After the concrete has begun to harden i.e. about 1 to 2
hours after its laying, it is protected with moist gunny hags, sand or any other
material approved by the Engineer-in-Charge against quick drying.
After 24 hours of laying of concrete the surface is cured by flooding withwater of about 25 mm depth or by covering with wet absorbent materials.
The curing is done for a minimum period of 14 days.
Over the foundation concrete, the masonry work may be started after 48 hours
of its laying, but the curing of cement concrete is continued along with the
masonry work for a minimum period of 14 days. In case of cement concrete
used as sub-grade for flooring, the flooring may be commenced before the
curing period of sub-grade is over but the curing of sub-grade is continued
along with the top layer of flooring for a minimum period of 14 days. The
water used for curing shall not produce any objectionably stains or unsightly
deposit on concrete surface.
Form work: If centering and shuttering are required to be done for this work
this are done in accordance with the specifications for form work under
Reinforced cement concrete.
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Reinforced cement
concrete (R.C.C.)
Same as cement concrete
except the size of coarse
aggregate is 20 mm unless
specially mentioned in the type
of work.Form work includes all forms
or moulds required for forming
the concrete which is cast-in-
situ, together with all
temporary construction
required for their support.
Form work is of plywood, or
steel approved by the Engineer-
in-Charge. Timber used for
form work should be easily
workable with nails withoutsplitting and of light weight. It
is stiff and strong enough to
avoid undue deflection when
loaded and not liable to warp
when exposed to sun and rain or
wetted during casting of
concrete.
Form work is of rigid
construction true to shape and
dimensions shown on drawings.
It is st rong enough to withstandthe dead and live loads and
forces caused by ramming and
vibrations of concrete and other
incidental loads imposed upon
it during and after casting of
concrete. It is made sufficiently
rigid by using adequate number
of braces and ties. To make up
Same as
cement
concrete.
Propping and Centerin g: Props used for centering are of steel, timber, posts,
ballies or any other material approved by the Engineer-in-Charge. In case
when ballies are used none is less than 100 mm in diameter measured at mid
length and 80 mm at thin end. Ballies rest on wooden sole plates of not less
than 40 mm thickness having a minimum bearing area of 0.1 square metre laidon ground or on 40 X 40 mm thick brick masonry pillars in mud mortar of
height not exceeding 40 cm. All props are further provided with double
wedges between the sole plates and the props so as to facilitate tightening and
easing of shuttering without causing shock to the concrete.
In case a span exceeds 4.50 metres and height exceeds 3.50 metres , suitable
horizontal as well as diagonal bracings are provided after accounting for all
forces including action of the wind which may produce lateral forces. In
case, the height of centering exceeds 3.50 metres, the props may be provided
in multi-stages. The detail of splicing the props at each stage is as per
approved drawing.
Before the casting of concrete is started, the props and wedges are thoroughly
checked to see that these are intact. While the casting of concrete is in
progress, at least one carpenter is to keep a constant watch on the props and
take immediate remedial measures, as soon as any of them gets loosened.
Shuttering: The shuttering is of approved dressed timber of well seasoned
wooden boards to give a smooth and even surface and the joints do not permit
leakage of cement grout. The timber is free from loose knots, projected nails,
splits, adhering grout or other defects that may mar the cement surface of
concrete. It is not be so green or wet as to shrink after erection. Species of
timber which are not affected appreciably by its contact with water are used.
When metal forms are used, all bolts and nuts are countersunk and wellground to provide a smooth plain surface. Opening for fan clamps and other
fittings connected with services are provided in the shuttering as directed by
the Engineer-in-Charge.
Surface treatment f or shuttering: The surfaces of timber shuttering that
would come in contact with concrete are thoroughly cleaned and well wetted
and coated with soap solution, raw linseed oil, or form oil of approved
manufacture, or any other approved material such as polythene sheets, to
Regular
mandatory
tests on the
consistency
andworkability
of the fresh
concrete are
done to
achieve thespecified
compressive
strength of
concrete.
Work tests
and slump
tests arecarried out as
per standing
practice.
Three test
specimens
are made
from each
sample for
testing at 28
days.
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any settlement in the form work
either before of during the
placing of concrete, hard wood
wedges are provided where
required.
All form work is so constructed
as to be removable in sections
in the desired sequence, without
damaging the surface ofconcrete or disturbing other
sections. Forms should be easy
to strip after connecting and no
piece should be keyed into the
concrete. The completed form
work is approved after
inspection by the Engineer-in-Charge before the
reinforcement bars are placed in
position.
prevent adhesion of concrete to form work.
The Engineer-in-Charge inspects and accepts the form work as to its strength,
alignment and general fitness before placing any concrete in the forms. But
such inspection is not to relieve the contractor of his responsibility for safetyof man, machinery, materials and for results obtained.
Camber: Suitable camber is provided in horizontal members of structures
especially in long members to counteract the effects of deflection. The
camber for beams and slabs are 4 mm per metre i.e. 1 in 250 and forcantilevers, at free end is
1/50
thof the projected length or as directed by the
Engineer-in-Charge.
Removal of Form Work: The form work is removed avoiding shock or
vibration that may cause any damage to concrete. In a slab and beam
construction, sides of the beam are stripped first; then the undersides of slab
and lastly the undersides of the beam. The period that elapses after the
concrete has been laid before undertaking the work of easing and removal ofcentering and shuttering is as given below according to IS 456-1978.
Parts of structure
1- Walls, columns and
vertical faces
of all structural
members
2- Slabs (props leftunder)
3- Beams soffits(props left under)
4- Removal of propsunder slabs
Where ordinary Portland cement is
used forms may be removed after
expiry of the following periods:
24 to 48 hours as may be decided by the
Engineer-in-Charge.
3 days
7 days
7 days
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.
(a) Spanning up to4.5m
(b) Spanning over 4.5m
5- Removal of propsunder beams and
arches:
(a) Spanning up to 6 m(b) Spanning over 6 m
7 days
14 days
14 days21 days
Reinforcement: Mild steel barsshall conform to the I.S.
specification, free from loose
rust, dust, loose mill scales,
coats of paints, oil or other
coatings which may destroy or
reduce bond. It is stored in
such a way so as to avoid
distortion and to prevent
corrosion.
In case of cantilever slabs and beams, the centering will remain till structures
for bearing down have been erected and have sufficient strength.
Bending of Overl apping: Bars are bent cold, correctly and accurately to thesize and shape as shown on the detailed drawing or as directed by the
Engineer-in-Charge. Preferably bars of full length are used. Overlapping of
bars, where necessary, is done as directed by the Engineer-in-Charge. The
overlaps are staggered for different bars and located at points, along the span,
where, neither shear nor bending moment is maximum. Overlapping of bars
can be kept apart by 25 mm or 11/4 times the maximum size of coarse
aggregate, whichever is greater, with concrete between them. But where this
cannot be done, the overlapping bars are bound together at intervals not
exceeding twice the diameter of such bars, with two strands of annealed steel
wire of 0.90 mm to 1.6 mm thickness twisted tight. In case of mild steel the
ends of rods are bent in to semi-circular hooks, having clear diameter equal to
four times the diameter of bar, with a length beyond the bend equal to fourtimes the diameter of the bar. In case of mild steel the ends of rods are bent in
to semi-circular hooks, having clear diameter equal to four times the diameter
of bar, with a length beyond the bend equal to four times the diameter of the
bar. In case of deformed bars the hooks are not required. Welding of bars are
permitted in lieu of overlap if approved by the Engineer-in-Charge.
Placing in Positi on: Reinforcement bars are placed in position as shown in
the drawings. Bars at their points of intersection are securely tied together
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with two strands of annealed steel wire 0.90 to 1.6 mm thick twisted tight to
make the skeleton of the steel work rigid so that the reinforcement does not
get displaced during the deposition of concrete. Tack welding is permitted in
lieu of binding with steel wire if approved by the Engineerin-Charge.
The bars are kept in position by the following methods as the case may be:
(1) For beam and slab construction, pre-cast cover blocks in cement mortar
1:2 about 4 X 4 cm section and of thickness equal to the specified cover are
placed between the bars and shuttering, to avoid sagging and to maintainrequisite cover of concrete.
(2) For cantilevered and double reinforced beams or slabs the vertical
distance between the horizontal bars are maintained by introducing chain
spacers or support bars of steel at 1.0 metre or at shorter spacing to avoid
sagging.
(3) For columns and walls the vertical bars are kept in position by means of
timber templates with slots accurately cut in them; or with block of cement
mortar (1:2) suitably tied to the reinforcement.
Mixing: Concrete is mixed by mechanical mixer except for small quantity
when Engineer-in-Charge permits otherwise. Same as Cement Concrete.
Consistency or Workabil ity: The concrete, which will flow sluggishly into the
forms and around the reinforcement without any segregation of coarse
aggregate from the mortar, is used. The consistency will depend on whether
the concrete is vibrated or hand tamped. It is determined by slump tests as
per I.S. recommendation.
Placing of concrete: Pouring into moulds. Placing of concrete is
commenced only after the Engineer-in-Charge has inspected the centering,
shuttering and reinforcements as placed and approved the same. Shuttering is
clean and free from all saw dust, pieces of wood or other foreign materials
and is treated as prescribed in surface treatment for shuttering.
In case of casting of concrete of slabs and beams, wooden planks or cat-walks
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supported directly on the centering by means of wooden blocks are provided
to convey the concrete to the place of deposition without disturbing the
reinforcement. Labourers are not allowed to walk over the reinforcement.
In deep trenches and footings, concrete is placed through chutes as directed bythe Engineer-in-Charge. In case of columns and walls, the shuttering is so
adjusted that the vertical drop of concrete is not more than 1.5 metes at a time.
During cold weather, with below 4.5oC temperature, laying of concrete is not
done. During hot weather, precaution is taken to see that the temperature of
wet concrete does not exceed 38oC. Unless permitted by the Engineer-in-
Charge no concrete is laid within half an hour of the closing time of the day.
The time between mixing and placing of concrete is not to exceed the initial
setting time of cement of 30 minutes.
Compaction: Concrete is compacted into a dense mass immediately after
placing by means of mechanical vibrators designed for continuous operations
during the whole period occupied for placing of concrete. The vibrators areso adjusted that the centers of vibrations approximates to the centre of the
mass being compacted at the time of placing. For certain items, such as roof
slab, depending on the thickness of the members and feasibility of vibrating
the same, the Engineer-in-Charge may permit hand compaction. Hand
compaction is done with the help of 16 mm diameter steel tamping rod and
tamping with wooden tampers so that the concrete is thoroughly compacted
and completely worked around the reinforcement and into corners of the form
work. The layers of concrete are so placed that the bottom layer does not
finally set before the top layer is placed.
Compaction is continued until the mortar fills the spaces between the coarse
aggregate and begins to cream up to form an even surface. Needle Vibratorsare withdrawn slowly so as to prevent formation of loose pockets in the case
of internal vibrators. The specific instructions of the makers of the particular
type of vibrator used are strictly complied with. Shaking of reinforcement for
the purpose of compaction is avoided. Compaction is completed before the
initial setting starts. Over-vibration or vibration of very wet mixes are
harmful and is avoided; under vibration is also harmful.
Construction Joi nts: The positions where construction joints are to be made
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will be as shown in structural drawing or as directed by the Engineer-in-
Charge. Such joints are kept to the minimum and are located where the shear
force is minimum and these are straight and at right angles to the direction of
main reinforcement.
When stopping the concrete on a vertical plane in slabs and beams, an
approved, stop-board is placed with necessary slots reinforcement bars or any
other obstruction to pass the bars freely without bending. The construction
joints on a vertical plane are keyed. Inclined or feather joints are not
permitted. Any concrete flowing through the joints of stop-board is removedsoon after the initial set. When concrete is stopped on a horizontal plane, the
surface is roughened and cleaned after the initial set. In case of columns, the
joints are horizontal and 10 to 15 cm below the bottom of beam running into
the column head. Concreting is carried out continuously up to construction
joints.
When the work has to be resumed, the joint are thoroughly cleaned with wirebrush and loose particles removed. A coat of neat cement slurry at the rate of
2.75kg of cement per square metre is then applied on the roughened surface
before fresh concrete is laid.
Curing: same as cement concrete.
Finishing:In case of roof slabs the top surface is finished even and smooth
with wooden trowel, before the concrete begins to set.
Immediately on removal of forms, the R.C.C. work is examined by the
Engineer-in-Charge, before any defects are made good. The work that has
sagged or contains honeycombing to an extent detrimental to structural safetyor architectural concept is rejected. Surface defects of a minor nature may be
accepted but should be made good as per direction of the Engineer-in-
Charge. The R.C.C. work is done carefully so that the thickness of plaster
required for finishing the surface is not more than 6 mm.
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Masonry work in
Superstructure
1st Class
Brickwork
Bricks are first class of standard
specification, regular in shape
and size with sharp edges andcorners. They shall emit a clear
ringing sound on being struck.
They is of uniform deep red or
copper colour, free from cracks,
chips, efflorescence, flaws andlumps of any kind. Dry bricks
shall not absorb more than 20%
of their weight when immersed
in water for 24 hours. Brick
shall have an average
compressive strength of not less
than 100kg per sq cm and notmore than 125 kg per sq cm.
For cement mortar, cement is
fresh Portland cement of
standard quality. Sand is
medium coarse sand, clean,
sharp and free from clay, mica
or organic matter. For lime
mortar, lime is slaked and fresh
stone-lime screened at work site
conforming to standard
specification. Surki is madefrom first class brick having
uniform colour and free from
admixture of foreign matter.
Water used is clean and
reasonably free from oils, acids,
alkalies, salts and vegetable
growth. Generally potable
Soaking of Br icks: all bricks are thoroughly soaked in water by submerging
them in clean water for at least four hours just before use. The wetted bricks
are stacked on a clean platform to avoid any contact with mud.
Laying: The bricklaying is of English bond unless specially mentioned. A
layer of mortar is spread on full width over a suitable length of the lower
course. Each brick is properly bedded with frog upward and set home (in
position) by gently tapping with handle of trowel or wooden mallet. Its inside
faces are buttered with mortar before the next brick is laid and pressed
against it. On completion of a course, all vertical joints are fully filled from
the top with mortar. Half, or cut bricks is not used except where necessary to
complete the bond. No damaged or broken bricks are used. Closers in such
cases, is cut to the required size and used near the ends of the walls. In
exposed brickwork, selected bricks of the specified class are used for face
work. The brickwork is true to line, plumb and all vertical joints are trulyvertical. Vertical joints in alternate courses shall come directly one over the
other. Thickness of brick course is kept uniform. All connected brickwork is
carried up simultaneously and no portion of work is left more than one metre
below the rest of the work. Where this are not possible, in the opinion of the
Engineer-in=Charge, the work is raked back according to bond (and not
toothed) at an angle not steeper than 45o. The work done per day should not
be more than one metre height. All iron fixtures, pipes, outlets of water, hold
fasts of doors and windows, which are required to be built into walls are
embedded in mortar or cement concrete as specified in their correct position
as per direction, as the work proceeds.
Joints: Brick is so laid that all joints are full of mortar. The thickness ofjoints shall not exceed 1.0 cm. All face joints are raked to a minimum depth
of 15 mm by raking tool during the progress of work when the mortar is still
green so as to provide proper key for plastering or pointing to be done. The
face of brickwork is cleaned on the same day on which brickwork is laid and
all mortar droppings removed promptly.
Brick Coping: The top courses of all plinth, parapet, steps and top wall below
R.C.C. is laid with brick on edges unless specified otherwise.
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Reinforced
Brickwork
water is used.
Mortar: The brickwork is done
with the specified mortar
(cement or lime) mixing theingredients in the specified
proportion. In the case of
cement mortar the unit of
measurement for cement is a
bag of cement and this are takenas 0.035 cu m. Sand in
specified proportion is
measured in boxes of suitable
size 35 cm X 25 40 cm. Sand is
measured on the basis of its dry
volume. In case of damp sand,
its quantity is increased suitablyto allow for bulkage. Materials
of mortar is first mixed dry till
of uniform colour on a solid
clean watertight platform and
then mixed wet at least three
times by adding water gradually
and evenly to have a workable
consistency of a stiff paste.
Only the quantity of cement
mortar which can be used
within 30 minutes are prepared
at a time. In case of limemortar, it is used on the day it is
made.
All bricks are of first class
quality and free from soluble
salt.
The mortar will consist of 1
part of fresh Portland cement
Curing: Brickwork is protected from rain by suitable covering when the
mortar is green. Masonry work in cement mortar or lime mortar is dept
constantly moist on all faces for a minimum period of seven days. Brickwork
carried out during the day is suitably marked indicating the date on which thework is done so as to deep a watch on the curing period.
Scaffolding: For all exposed brickwork, double scaffolding having two sets of
vertical supports are provided. The supports are sound and strong, tied
together with horizontal pieces over which scaffolding planks are fixed. Forall other brickwork in buildings, single scaffolding is permitted. In such
cases, the inner end of the horizontal scaffolding pole shall rest in a hole
provided only in the header course for the purpose. Only one header for each
pole is left out. Such holes for scaffolding shall, however, not be allowed in
pillars or columns less than one metre in width. The holes left in masonry
works for scaffolding purposes are filled and make good before plastering.
Laying of bricks: All bricks are thoroughly saturated by submerging them in
clear water for at least four hours before use. A line of bricks are first laid
with frogs downward in each direction to act as guide and to ensure that
cutting of brick is avoided. In case, a part brick has to be introduced this are
done at about the middle of the length. The gap between two lines of bricks
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Random
Rubble Stone
Masonry:
and 3 parts of coarse sand
passing through I.S sieve No.
480 and retain on No. 15 sieve
(i.e. between 4.75 mm to 5.5
mm).
Mild steel bars are straight and
free from rust, paint, grease etc.
All material as stated above
including water is of standard
specifications.
Shuttering will be of approved
dressed timber like seasoned
soft wooden boards of not less
than 3 cm thick. Faces incontact with concrete is free
from adhering grout, projection
nails, splits or such other
defects. Any timber that shows
any tendency to warp, shrink or
twist is adjusted. All shuttering
and framing is rigid, well
braced and sufficiently strong to
stand the pressure of wet bricks.
All props of approved size is
supported on double wedges.
Stone for random rubble stone
masonry is hard; sound free
from decay and weathering.
Stones with porous matter or
with boulder skin are rejected.
The size of stones are not less
than 15 cm in any direction.
for the reinforced joint is not less than 4 cm or three times the diameter of the
reinforced rods whichever is greater. For roof slabs, bricks are arranged in
such a way so that the inner edge of the wall and the reinforced joint do not lie
on the same line.
Laying of r einforcement: Reinforcement rods are then laid exactly at the
centre of the joint. The rods do not touch the bricks at any place.
Overlapping of bars are avoided as far as possible by using bars of the
required length, but where this cannot be done a lap of 45 times diameter of
the bar is given with the necessary hooks at the ends and two rods are wired
along the lap.
Laying of mortar: Mortar of cement and sand in the proportion 1:3 is first
mixed dry on a solid, clean platform and then is mixed wet at least three times
by adding clean water gradually and evenly. The mortar is placed into the
gaps in between the bricks within 30 minutes, surrounding the reinforced
rods. Care is taken that bottom of rods in the slabs have the correct cover ofmortar under them. The filling of joints by mortar is carried out continuously
and no portion of mortar is allowed to start its initial set before the
neighboring mortar is in its place.
Curing: The work is not to be disturbed and should be kept wet for at lest 7
days.
Removal of centering: The centering is removed after 10 days without any
jerking of any kind.
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Coursed
Rubble Stone
Masonry
Cement and sand for cement
mortar or lime and surkhi
(sand) for lime mortar are of
standard specification.
Same as specified in Random
Rubble Masonry.
Mortar: The ingredients of mortar, cement and sand or lime and surki are
first mixed dry in the specified proportion till of uniform colour on a solid
clean platform and then mixed wet at least three times by adding watergradually and evenly.
Laying: All stones are first thoroughly wetted before laying. The stones are
hammer dressed with wooden mallet on the bed and from all other faces to
enable them to come into close proximity with each other securing close joint.
The walls are carried up truly plumb. Face stone is not narrower than its
height and is tailed back and bond well into the backing. The stones are
arranged to break joint on the face for at least half the height with those of
courses above or below. Stones are so laid that all joints are quite full of
mortar and the thickness of joints does not exceed 20 mm. Interstices between
stones are wedged with stone chips and spalls to avoid thick beds of joints and
mortar. In the interior thickness of the wall, bond stones at least 45 cm longare given one for every half sq m of face so as to approximately provide
through bond of long stones. The masonry is carried out together so as to
maintain uniform height as far as possible. If any part of a wall is required to
be raised in advance, toothing is formed by giving projections to bond with
the wall to be built later.
Curing: The work is to be protected from rain or sun while it is green. At
the end of the days work the topsof walls are left flooded. The masonry is
kept moist on all the faces for at least 7 days.
Laying: All stones are to be thoroughly wetted before laying. Every courseof stone is hammer dressed and laid truly horizontal and every vertical joint is
kept truly vertical. Faces are accurately squared and each face joint is dressed
at right angles. The face stones are laid alternate headers and stretchers. No
pinning is allowed on the face. Each course consists of stones of even
thickness not less than 3 cm and not more than 23 cm. No stones in face are to
have less breadth than height and no stone is tailed into the wall less than its
height. At least1/3
rd of the face stones are tailed into the wall twice their
height. The masonry is carried up regularly and true to plumb. The thickness
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of joints are kept so as no to exceed 12 mm. In case plastering or pointing is
not to be carried out, the joints are struck flush and finished at the time of
laying.
Bond or through stones: The stones going through the wall are welldistributed provided in the whole wall by arranging them in a staggered
fashion in successive courses. The intervals of through stones are not be less
than 1.5 m in each course. For walls up to 60 cm thickness, a through stone
is extended from one face of the wall to other. But in case for wall of greater
thickness at least 15 cm side over-lapping headers forming a stone joint is
laid from face to back.
Quoins: Corner stones or quoins are dressed to correct angle. The short bed
of the stone is at least equal to height. The quoins are laid with header and
stretcher in alternative layers.
Curing: Same as described in Random Rubble stone masonry.
Damp Proof Course Coarse aggregate is of clean,
hard and dense stone chips 12
mm down and is washed before
use.
Sand is clean, sharp and coarse
of average 5 mm size and is free
from dust, and dirt and
screened before use.
Cement is fresh Portland
cement.
All the materials in use
including water proofing
D.P.C. of
cement
concrete should
have a mix of
1:2:4 or
1:11/2:3.
Usual thickness
2.5 cm to 4 cm.
Mixing: Coarse aggregate and sand are measured by volume with gauge
boxes and cement by bag having a weight of 50 kg or volume of 0.0347 cu m.
Some sample tests of cement bags are made at work site to ensure the
specified weight and volume.
The mixing is done on a clean solid platform. Dry coarse aggregate is stacked
evenly on the platform. Sand and cement in the specified quantities at first is
mixed dry till of uniform colour and spread over the stacked coarse aggregate.
The materials are mixed dry till of uniform colour and spread over the
stacked coarse aggregate. The materials are then turned over once without
adding water and then at least further 3 times, adding the required quantity of
water gradually and slowly to give a uniform concrete. Water-proofing
compound Pudlo or Cico @ 5 or 3 per cent by the weight of cement as
specified is mixed with concrete to make it water proof.
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compound are to be of their
respective standard
specifications.
Preparati on of base: The top of the walls on which damp-proof course is to
be laid is constructed with bricks on edge or with frogs of the bricks down.
The top of the plinth bed over which damp-proof course is to be placed is
thoroughly cleaned with a steel brush, washed and wetted before laying thecourse of concrete. Wooden straight edges are fixed on plinth wall having the
same inner width as that of the required with of the D.P.C.
Laying: Damp-proof course may be laid to the full width of the plinth or of
the superstructure as specified in the drawing or specially mentioned.
It is laid to the specified thickness (2.5 cm or 4 cm) over the plinth wall flush
with the floor surface and is not carried across the doorways or such other
openings.
D.P.C. is then consolidated by tamping and leveled both longitudinally and
transversely.
Laying is completed on same day; the joints or breaks are given at the door
opening. The surface of the concrete is roughened and chequered when air
dry so as to form a key for the joint with the brick wall above.
Curing: Damp-proof course is to be kept wet for at least 7 days after laying,
if the brickwork is not ready to proceed further.
But in any case no brickwork is commenced on the freshly laid damp-proof
course unless the D.P.C. has been flooded with water for at least 48 hours.
[Alternatively; the damp proof course may also be of 2 cm thick layer ofcement mortar (1:2) mixed with water-proofing compound or with 5% of
Pudlo by weight of cement. In this case only write the specifications of sand
and cement. The mixing is same as that of cement mortar for brickwork. All
other clauses are same as stated above]
Flooring
Brick on Edge
Flooring
Bricks of the specified strength
are used, conforming to its
Sub-grade: The sub-grade is provided with the slope required for the
flooring.
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standard specification. Broken
bricks are not used in the
flooring except for closing the
line. The bricks are laid on
edge.
Mortar: The mortar used is as
specified.
In case of dry brick flooring,fine sand is filled in the joints.
The sub-grade for flooring may be on concrete. In this case the plinth
masonry off-set are depressed so as to allow the sub-grade concrete to rest on
it.
In case of lime concrete sub-grade, it is allowed to set for seven days.
If the sub-grade is of lean cement concrete, the flooring is commenced within
48 hours of the laying of sub-grade failing which, the surface of sub-grade is
roughened with steel wire brushes without disturbing the concrete. Before
laying the flooring, the concrete sub-grade is made wet and a coat of cement
slurry at the rate of 2 kg per sq m is spread over the prepared sub-base in
order to get a good bond between sub-grade and flooring.
Where concrete sub-grade is not provided, the earth below is properly sloped,
watered, rammed and consolidated.
Before laying the flooring, it is moistened.
Soaking of bri cks: Bricks required for flooring are thoroughly soaked in
stacks before use by spraying clean water sufficiently at regular intervals for
a period of not less than six hours so as to keep wet to the satisfaction of the
Engineer-in Charge. In case the joints are to be filled with sand, the bricks
need not be soaked.
Laying: The bricks are laid on edge in plain, diagonal herring bond or other
pattern as specified or directed.
Bricks are laid on edge on 12 mm thick mortar bed, and each brick isproperly bedded and set home by gently tapping with handled trowel or
wooden mallet. The inside faces are buttered with mortar, before the next
brick is laid and pressed on it. The vertical joints are fully filled from the top
with mortar. The surface of the flooring, during laying, is frequently checked
with a straight edge at least 2 m. long, so as to obtain a true plain surface
with the required slope. Dry brick flooring is laid on a bed of 12 mm thick
mud mortar with the required slope.
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Terrace
Flooring over
brick flat
Artificial
stone flooring
Bricks ballast that will pass
through 3 cm dia. Ring, surki
and lime are of their standardspecifications.
Usual thickness are 2.5 cm.
The ingredients are cement,
The ingredients
are mixed at
first dry andthen wet to the
required
proportion (100
brick ballast:
36 surkhi: 18
lime as are
usual).
1:2:4 or as
specified.
Joints: All bricks are so laid that every joint becomes full of mortar. All face
joints are raked to a minimum depth of 15 mm by raking tool during the
progress of work when the mortar is still green in order to provide proper key
for the pointing or plastering to be done. If plastering or pointing is not
required to be done, the joints are struck flush and finished at the time oflaying. The face of brickwork is cleaned on the same day on which the
brickwork is laid and all mortar droppings removed promptly. For dry brick
flooring joints are as fine as possible and not exceeding 5 mm and are filled
up with fine sand.
Curing: Except dry brick flooring the work is protected form rain by suitable
covering when the mortar is green and is kept constantly moist for a minimum
period of 7 days.
Preparation of base: Excess earth or sand that has been thoroughly
compacted in the plinth is removed to a depth equal to the thickness of the
floor to provide room for this. The bed is then dressed with required slope ofthe floor towards its water outlet. A layer of second class or picked jhama
brick as specially mentioned are then laid with break joints and the small gaps
between them are filled up with local fine sand.
Placing of concrete: The concrete is then laid to the specified thickness and
thoroughly rammed and consolidated into position till the surface is smooth
and no further impression can be made.
During ramming lime water is sprinkled on the surface to keep the concrete
wet. Corners and edges where ramming is difficult are specially to be
consolidated by wooden battens according to the direction of the Engineer-in-
Charge. The surface is checked frequently with spirit level and woodenstraight edge to have a true surface.
Curing: The floor is kept wet for at least a week.
Sub-grade: The sub-grade is provided with the slopes required for the
flooring. Flooring in verandah, kitchen, baths, water-closets and courtyards
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or Cement
concrete
flooring
sand and stone chips.
This are also known as patent
stone flooring when crushed
blast surface slag is used ascoarse aggregate.
Coarse aggregate is stone chips
well graded from 12 mm down,
free from dust, dirt etc. hard andrough.
Sand is coarse 5 mm maximum
size, clean, free from dirt etc.
Cement is fresh Portland
cement.
All the materials as stated
above and water comply with
their respective standard
specifications.
are invariably to be provided with suitable slope to drain off waste and rain
water. Plinth masonry off-sets are depressed so as to allow the sub-grade
concrete to rest on it.
If the sub-grade consists of lime concrete, it is allowed to set for seven daysand the flooring is laid in the next three days.
If the sub-grade is of lean concrete, the flooring is commenced preferably
within 48 hours of the laying of sub-grade.
The surface of the sub-grade is roughened with steel wire brushes without
disturbing the concrete. The sub-grade may also be R.C.C. slab.
In all cases the surface is cleaned and before laying the flooring, the sub-grade
is wetted with a coat of cement slurry at 2 kg of cement spread over an area of
one sq m so as to get a good bond between the sub-grade and concrete floor.
Mixing: Mixing of concrete is done by hand or by mechanical mixer. In case
of hand mixing the cement and sand are at first mixed dry and this dry
mixture is further mixed with dry coarse aggregate till the coarse aggregate is
well coated with dry mix of cement and sand. Required amount of water - 32
litres per bag of cement as per water cement ratio is added slowly and
gradually to mix the concrete wet to have a uniform plastic mix. The mixture
will have a slump of not more than 4 cm. Concrete for one panel only is
mixed at one lot.
Laying: Flooring of specified thickness are laid in the pattern as given in the
drawings or as directed by the Engineer-in-Charge. The panel is of uniform
size and no dimension of a panel will exceed 2m and the area of panels willnot be more than 2 sq m. The whole operation of laying in one panel is
completed within 30 minutes.
Laying with strips: Normally cement flooring is laid in one operation using
glass or plain asbestos sheet strips at the junction of two panels. This method
ensures uniformity in colour of all the panels and straightness at the junction
of the panels.
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Strips fi xing: 4 mm thick glass strips or 5 mm thick plain asbestos strips are
fixed with their top at proper level, giving required slopes.
Laying without strips: Laying of cement concrete flooring in alternate panels
may be allowed by Engineer-in-Charge in case strips are not to be provided.
Shuttering: The panels are bounded by wooded battens. The battens should
have the same depth as the concrete flooring. These are fixed in position,
with their top at proper level, giving required slopes. The surface of the
battens that come in contact with concrete is oiled with raw linseed oil or a
coat of soap solution may be applied before casting the concrete.
Castin g of concrete: The concrete is placed gently and evenly spread within
the panel and thoroughly compacted with wooden thapies to the required
thickness. The surface is then smoothed with wooden floats. The battens
used for shuttering, are removed on the next day of the laying of cement
concrete. The ends thus exposed are repaired, if damaged, with cementmortar 1 cement: 2 coarse sand, and allowed to set for a minimum period of
24 hours. The alternate panels are then cleaned of dust, mortar-droppings etc.
While laying concrete, care is taken to see that the edges of the previously laid
panels are not damaged and fresh mortar is not splashed over them.
Finishing: The surface is left for some time, till moisture disappears from it.
Excessive trowelling is avoided. Use of dry cement or cement and sand
mixture sprinkled on the surface to stiffen the concrete or absorb excessive
moisture, is not permitted. Fresh quantity of cement at 2.0 kg of cement is
mixed with water to form thick slurry and spread over an area of one sq m of
flooring while the concrete is still green. The cement slurry is then properly
pressed and finished smooth. The men engaged in finishing operation areprovided with raised wooden platform to sit on, so as to prevent damage to
new work.
Curing: the curing is done for a minimum period of ten days. Curing will not
commence until the top layer has hardened. Covering with empty cement
gunnies are avoided as the colour is likely to be bleached with the remnants of
cement matter from the bags.
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Patent stone
floor
Cement
concrete
flooring with
topping of red
oxide of iron
The proportion
of mix is 1:2:4
(4 graded stone
chips 12.5 mm
nominal gauge)by volume
unless
otherwise
described.
The preparation and method of construction is the same as that of the
artificial stone or cement concrete floor. The only difference is that the
coarse aggregate is of crushed blast furnace slag.
Sub-grade: it is as specified for artificial stone flooring.
Under layer: The under layer of flooring is of cement concrete of specified
thickness. As regards cement concrete the work is carried out in the manner
conforming to the specification of artificial stone flooring. As regards laying
the work, it is carried out in the manner specified in artificial stone flooring
except that:
a. the wooden battens used for shuttering are to be the heightof both, under and top layers of the floor;
b. the under layer is roughened with 2 mm deep diagonal linesat 7.5 cm centres both ways with a scratching tool to form akey for the finishing coat of red oxide of iron, no cement
slurry being added to the concrete surface, and
c. The battens are removed only 24 hours after the top layerhas been laid. The surface of the under layer is left even
and true to slope.
Top layer: This consists of uniform and smooth layer of plaster of specified
thickness (generally 10 mm) and of mix 1:3 (1 cement: 3 coarse sand), unless
otherwise specified, finished with a floating coat of neat cement. Unless
mentioned 3.5 kg. of red oxide of approved quality to 50 kg of cement is to be
mixed thoroughly by hand till of uniform colour and then sand added and
mixed. The full quantity of dry mortar required for a room is prepared in onelot in order to ensure uniform colour, water is then added to form a stiff paste
in the usual manner as and when required.
Laying: The top layer is laid, the following day after the under layer has
been laid. The plaster is done to a uniform thickness, of 10 mm and finished
smooth with cement slurry (2.0 kg of cement red oxide mix per square meter
of flooring mixed in the ratio used) for the plaster. The surface is then
brought to a fine polish by use of polishing stones.
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Terrazzo or
Mosaic
Flooring
The terrazzo floor consists of
two layers, the under layer
usually of 20 mm thick cement
concrete 1:2:4 or as specifiedand the top layer usually 6 mm
thick terrazzo consisting of
cement, marble powder, marble
chips in the specified proportion
and water.
The battens used for shuttering of panels are removed the next day after
laying of the top layer and broken edges repaired with the same coloured
mortar as in plaster.
Curing: The curing is done for a minimum period of ten days. Curing is not
to commence until top layer has hardened. Covering with empty cement
gunnies are avoided as the colour is likely to be bleached with the remnant of
cement matter from the bags.
Under layer: Coarse aggregate for cement concrete is of granite stone chips
of 12 mm gauge, sand is coarse, cement is fresh Portland cement each of them
with their standard specification. Cement concrete of specified mix usually
1:2:4 is prepared following the standard specification as for cement concretework. The bed for the under layer is cleaned and cement slurry @ 2.0 kg per
sq. m is applied before laying of under layer over the cement concrete or
R.C.C. surface. The whole area is divided into panels of uniform size by 4 to
6 mm glass strips or 2 mm aluminum strips with their tops at proper level,
giving slopes. Each panel will not exceed 2 sq. m in area and 2 m in length
for inside situations. In exposed situations the length of any side of the panel
will not be more than 1.25 metres. Cement slurry @ 2.0 kg per sq m is
applied before laying of under bed over concrete or R.C.C. surface. The
concrete is laid within the panel and thoroughly compacted with wooden
thapies with the required thickness generally 20 mm and smoothed with
wooden floats.
Top layer: The mix for terrazzo topping will consist of cement with or without
pigment, marble powder, marble chips and water. The marble chips can be
white or pink, black, yellow or any other colour as specified. These are hard,
sound dense and homogeneous in texture. These are uniform in colour and
free from stains, cracks, decay and weathering. For 6 mm to top layer, size of
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marble chips are 1 to 2 mm. The minimum thickness of topping is not less
than 11/3times the maximum size of chips. The cement to be used is ordinary
grey cement or white cement of required shade as specified. Colouring
matter where specified is mixed dry thoroughly with the cement and marble
powder and then marble chips added and mixed as specified. The fullquantity of dry mixture of mortar required for a room is prepared in a lot in
order to ensure a uniform colour.
The mixture is stored in a dry place and well covered and protected from
moisture. The dry mortar is homogeneous and stiff and contains justsufficient water to make it workable.
The terrazzo topping is laid while the under layer is still plastic, but has
hardened, this are normally achieved between 18 to 24 hours after the under
layer has been laid. A cement slurry preferably of the same colour as the
topping is be brushed on the surface immediately before laying is commenced.
It is laid to a uniform thickness slightly more than that specif ied in order toget the specified finished thickness after rubbing. The surface of the top layer
is trowelled over, pressed and brought true to required level by a straight
edge and steel floats in such a manner that the maximum amount of marble
chips come up and spread uniformly over the surface.
Polishing, Curing and Finishing: Polishing is done by machine. About 36
hours after laying the top layer the surface is watered and ground evenly with
machine fitted with rapid cutting grit blocks (carborundum stone) of coarse
grade (No. 60) till the marble chips are evenly exposed and the floor is
smooth. After first grinding, the surface is thoroughly washed to remove all
grinding mud and covered with a grout of cement and colouring matter in
same mix and proportion as the topping in order to fill any pin holes thatappear. The surface is allowed to cure for 5 to 7 days and then ground with
machine fitted with fine grit blocks (No. 120). The surface is cleaned and
repaired as before and allowed to cure again for 3 to 5 days. Finally the third
grinding is done with machine fitted with finest grade grit blocks (No. 320) to
get even and smooth surface without pin holes. The finished surface should
show the marble chips evenly exposed.
Where use of machinefor polishing is not feasible rubbing, and polishing is
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Pre-cast
terrazzo tile
Flooring
Terrazzo tiles generally
conform to IS-1237 (modified
up to date). The specific sizes
of tiles are used. When the
nominal size of a tile is 20 cm x
20 cm the actual size is 19.85
cm X 29. 85 cm and thicknessare not less than 25 mm.
Tolerances on length and
breadth are plus or minus one
millimeter; tolerance on
thickness are plus or minus 5
mm.
The tiles are manufactured
under hydraulic pressure of not
less than 140 kg per square
centimeter and are given the
first grinding with machinebefore delivery to site. The
proportion of cement to
aggregate in the backing of the
tiles are not leaner than 1:3 by
weight. The finished thickness
of the upper layer is not less
then 5 mm for size of marble
chips from the smallest up to 6
done by hand in the same manner as specified for machine polishing except
that carborundum stone is grade No. 60 for 1st
rubbing, grade No. 80 for 2nd
rubbing and grade No. 120 for final rubbing and polishing.
After the final polish, oxalic acid is dusted over the surface @ 33 gm persquare metre sprinkled with water and rubbed hard with a pad of woolen rags.
The following day, the floor is wiped with a moist ran and dried with a soft
cloth and finished clean.
Preparation of Surface: Sub-grade concrete or the R.C.C. slab on which the
tiles are to be laid is cleaned, wetted and mopped. The bedding for the tiles
are of lime mortar of either 1 lime putty: 1surkhi:2 coarse sand or 1 lime
putty: 3 surki or 1 lime putty: 3 coarse sand. The ingredients are thoroughly
mixed by volume in dry form. Care is taken to ensure that there are no hard
lumps present. Water is then added and the ingredients thoroughly mixed.
The average thickness of the bedding mortar is 30 mm and the thickness atany place is not less than 10 mm.
Laying: Lime mortar bedding is spread, tamped and corrected to proper
levels and allowed to harden for a day before the tiles are set. Over this
bedding, neat grey cement slurry of honey like consistency is spread at the
rate of 4.4 dg of cement per square meter over such an area as would
accommodate about twenty tiles. Tiles are washed clean and are fixed in this
grout one after another, each tile being gently tapped with a wooden mallet till
it is evenly bedded, and in level with the adjoining tiles. The joints are kept as
thin as possible not exceeding 1.5 mm and in straight lines or to suit the
required pattern. The surface of the flooring is checked with a straight edge
during laying of each tile, so as to obtain a true surface with the requiredslope. When full size tiles cannot be fixed, these are cut to the required size
with straight edge, rubbed smooth to ensure a straight and true joint. Tiles
which are fixed in the floor adjoining the wall enter not less than 12 mm
under the skirting or dado. After the tiles have been laid, surplus cement
grout that may have come out of the joint is cleaned off.
Curing, Polishing and F inishing: The day after tiles are laid all joints are
cleaned to a depth of 5 mm and all dust and loose mortar removed. Joints are
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mm. For other size of marble
chips, the finished thickness are
as specially mentioned.
then grounded with grey or white cement mixed with pigment to match the
shade of the topping of the wearing layer of the tiles. The same cement slurry
is applied to the entire surface of the tiles in a thin coat with a view to protect
the surface form abrasive damage and fill the pin holes that may exist on the
surface.
The floor is then kept wet for a minimum period of 7 days. The surface is
thereafter grounded evenly with machine fitted with coarse grade grit blocks
(No. 60). Water is used profusely during grinding. After grinding, the
surface is thoroughly washed to remove all grinded mud, cleaned andmopped. It is then covered with a thin coat of cement slurry mixed with
pigment as applied after laying the tiles. The surface is again cured. The
second grinding is then carried out with machine fitted with fine grade grit
blocks (No. 120). The final grinding with machine fitted with the finest grade
grit blocks (No. 320) is carried out the day after the second grinding as
described above. For small areas or where circumstances so require, hand
polishing may be permitted in lieu of machine polishing after laying. Forhand polishing, the following carborundrum stones are used: 1
stgrinding No.
60; second grinding, medium grade No. 80; and for final grinding, fine grade
No. 120. In all respects the process are similar to machine polishing.
After the final polish, oxalic acid is dusted over the surface at the rate for 33
gm per square metre sprinkled with water and rubbed hard with a pad of
woolen rags. The following day the floor is wiped with a moist rag and dried
with a soft cloth and finished clean.
Dado & Skirting
Terrazzo
Tiles
Terrazzo Tiles in Rises of Steps, Skirting and Dado:
Terrazzo Tiles: Same as specified in 15-39. The minimum finishedthickness are 12 mm. When the bigger sized chips are used, the tiles are not
less than 20 mm thick.
Preparation of surface: The joints are raked out to a depth of at least 15 mm
in masonry walls, while the masonry is being laid. In case of concrete walls,
the surfaces are roughened by hacking. The surface is cleaned thoroughly
and washed with water.
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Glazed Tiles
Laying: 12 mm thick cement mortar 1 cement: 3 coarse sand or mix as
specified is then applied and allowed to harden. The plaster is roughened with
wire brushes or by scratching diagonal lines at close intervals. The back of
tiles are buttered with a coat of grey cement slurry and edges with grey or
white cement slurry with or without pigment to match the shade of tiles, andset in the bedding mortar. The lines are then tamped and corrected to proper
planes and lines. The tiles are set in the required pattern and butt jointed. The
joints are as fine as possible. Top of skirting or dado is truly horizontal and
joints truly vertical except where otherwise mentioned.
The rises of steps, skirting or dado shall rest on the top of the tread or
flooring. Where full size tiles cannot be fixed, the tiles are cut to the required
size and their edges rubbed smooth.
Curing, Polishing and Finishing: Same as in article 15-39 shall hold good
as far as applicable. Polishing is done by hand.
Glazed Til es in Skir ting and Dado: Glazed Tiles: The tiles are of approved
made confirming to IS 777-1970. They are flat, and true to shape and free
from cracks, crazing spots, chipped edges and corners. The glazing is of
uniform shade.
The tiles are of nominal sizes as 150 x 150 mm and 100 x 100 mm or as
specified. The thickness of the tiles are 5 mm or 6 mm as specified. The top
of the tiles are completely free from glaze in order that the tile may adhere
properly to the base. The edges of the tiles are free from glaze, however, any
glaze it unavoidable, is permissible on any one edge of the tile.
Preparation of Surface: While the masonry is being laid, the joints are rakedout to a depth of at least 15 mm in masonry wall. In case of concrete wall, the
surfaces are roughened with wire brushes or by scratching diagonal at close
intervals.
Laying: 12 mm thick plaster of cement mortar 1 cement: 3 coarse sand or
mix as specified is applied and allowed to harden. The plaster is roughened
with were brushes or by scratching diagonal at close intervals.
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Cement
plaster
skirting
finished with
red oxide of
iron
(a band of plaster at thebottom of wall not
exceeding 30 cm in
height above the floor is
classified as skirting):
iron
Cement is fresh Portland
cement and sand is medium
quality, clean, free from
organic matter and salts. Red
oxide is of approved quality.
All the materials including
water is of I.S. specification.
The tiles should be soaked in water, washed clean, and a coat of cement
slurry applied liberally at the back of tiles and set in the bedding mortar. The
tiles are tamped and corrected to proper plane and lines. The tiles are set in
the required pattern and butt jointed. The joints are as fine as possible. Top
of skirting of dado is truly horizontal and joints truly vertical unless speciallymentioned. Skirting and dado shall rest on the top of the flooring. Where full
size tiles cannot be fixed these is cut to the required size and their edges
rubbed smooth.
Curing and Finishing: The joints are cleaned off the grey cement grout withwire brush or trowel to a depth of 2 mm to 3 mm and all dust and loose mortar
removed. Joints are then flush pointed with white cement added with
pigments if required to match the colour of tiles. The surface is kept wet for 7
days. After curing, the surface shall not sound hollow when tapped with a
wooden mallet.
Thickness: The thickness of the skirting is measured exclusive the thicknessof key i.e. grooves or open joints in brickwork. The average thickness should
be regulated at the time of plastering by keeping suitable thickness of the
gauges. Extra thickness required in dubbing behind rounding of corners at
junctions of wall is ignored.
Preparation of wall surface: The joints are raked out to a depth of at least
15 mm in masonry wall, while the masonry is being laid. In case of concrete
walls, the surfaces are roughened by hacking. The surface is cleaned
thoroughly, washed with water and kept wet before skirting is commenced.
Application of under coat: The under coat of skirting is of cement plaster of
the thickness and mix described in the item. The cement plaster for undercoat is laid immediately after this are prepared. The under coat is finished
rough with a scratching tool to form a key for the top coat.
Mortar for top coat: This shall consist of uniform and smooth layer of
plaster of specified thickness and of mix 1: 3 (1 cement: 3 coarse sand) or as
specified. Unless specified 3.5 kg of red oxide to 50 kg of cement (i.e. per
bag) is mixed thoroughly with the cement and then sand added and mixed.
The full quantity of dry mortar required for a room is prepared in one lot in
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order to ensure uniform colour. Wet mortar is prepared in the usual manner
as and when required.
Application of top coat: The top coat is done the next day after the under
coat has been applied. The plaster is done to the thickness specified andfinished smooth, by application of cement red oxide mix at the rate of 1.0 kg
sq m of surface. The ratio is 3.5 kg of red oxide to 50 kg of cement if not
otherwise mentioned. When the surface has hardened sufficiently it is brought
to a fine polish by use of polishing stones.
Woodwork
Doors and
window
frames
Doors and
Timber is of teak, sal, deodar
etc. as mentioned, well
seasoned, dry, free from sap,
knots, crack or any other
defects or diseases. It is sawn
in the direction of the grains.
Sawing is truly straight andsquare. The scantling is
planned smooth and accurate to
the full dimensions, rebates,
roundings and mouldings as
shown in the drawing made,
before assembling. Patching or
plugging of any kind is not
permitted except as provided.
Specified timber is used, and it
Joints: These are mortise and tenon type, simple, neat and strong. Mortise
and tenon joints shall fit in fully and accurately without wedging or filling.
The joints are glued framed, put together and pinned with hardwood or
bamboo pins not less than 10 mm dia. After frames are put together pressed in
position by means of a press.
Surface Tr eatment: Wood work is not painted, oiled or otherwise treated
before it has been approved by the Engineer-in-Charge. All portions of
timber abutting against masonry or concrete or embedded in ground is
painted with approved wood primer or with boiling coal tar.
Gluing of Joints: The contract surface of tenon and mortise joints are treated
before putting together with bulk type synthetic resin adhesive of a make
approved by the Engineer-in-Charge.
Fixi ng in position: The frame is placed in position truly vertical before the
masonry reaches half the highest of the opening with iron clamps or as
directed by the Engineer-in-Charge. In case of door frames without sills, thevertical members are embedded in the flooring to a depth of 40 mm or as
directed by the Engineer-in-Charge. The door frames without sills while
being placed in position, is suitably strutted and wedged in order to prevent
warping during construction. The frames shall also be protected from
damage, during construction.
Joinery work: All pieces are accurately cut and planned smooth to the full
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window
shutters
is well seasoned, dry, and free
from sap, knots crack or any
other defects or disease.
Patching or plugging of any
kind is not permitted except asprovided.
dimension. All members of the shutters are straight without any warp or bow
and shall have smooth, well planned faces at right angles to each other. In
case of paneled shutters the corners and edges of panels are finished into
grooves to the full depth of the groove leaving an air space of 1.5 mm and the
faces are closely fitted to the sides of the grove. In case of glazed shutter,sash bars shall have mitered joints with styles. Styles and rails are properly
and accurately mortised and tenoned. Rails which are more than 180 mm in
width shall have two tenons. Styles and end rails of shutters are made out of
one piece only. The tenons shall pass through styles for at least3/4th of the
width of the style. When assembling a leaf, styles are left projection as ahorn. The styles and rails shall have 12 mm groove in paneled portion for the
panel to fit in.
The depth of rebate in frames for housing the shutters shall in all cases be
1.25 cm and the rebate in shutters for closing in double shutter doors or
windows are not less then 2 mm. The rebate is splayed. The joints are
pressed, and secured by bamboo pins of about 6 mm diameter. The horns ofstyles are sawn off.
For battened shutters: Plank for battens are 20 mm thick unless otherwise
specified and of uniform width of 125 to 175 mm. These is planned and made
smooth, and provided with minimum 12 mm rebated joints,. The joint lines
are chamfered. Unless otherwise specified the battens for ledges and Braces
are 30 mm thick and fixed with the battens on the inside face of shutter with
minimum two number 50 mm long wood screws per batten. The ledges are
225 mm wide and braces 175 mm wide, unless otherwise specified. The
braces shall incline downwards towards the side on which the door is being
hung.
Glui ng of joints for panell ed or Gl azed shutters: The contact surfaces of
tenon and mortise joints are treated before putting together with bulk type
synthetic resin adhesive of a make approved by the Engineer-in-Charge.
Shutters are not painted, oiled or otherwise treated, before these are fixed in
position and passed by the Engineer-in-Charge.
For glazed shutters, mounting and glazing bars are tub-tenoned to the
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maximum depth which the size of the member world permit or to a depth of 25
mm, whichever is less.
Fittings: Details of fittings to be provided is as per the schedule of fittings
supplied by the Engineer-in-Charge in each case. The cost of providing andfixing shutters shall include the cost of hinges and necessary screws for fixing
the same. All other fittings are enumerated and paid for separately. The
fittings shall conform to their respective IS specifications. Where fittings are
stipulated to be supplied by the department free of cost, screws for fixing the
fittings are provided by the contractor and nothing extra will be paid for thesame.
Steel doors and
windows
Steel doors and window are
manufactured using rolled steel
sections of the weights
specified in IS: 1038 latest
issue. They is fixed, centrehung, top hung, bottom hung or
composite as specified. The
steel is of S.T. 32-0 grade
conforming to IS: 1977 or latest
issue.
Size: The steel doors and
windows are according to the
specified sizes and design. The
sizes of doors and windows are
calculated so as to allow 1.25
cm clearance on all four sidesof openings to allow for easy
fitting of door, windows and
ventilators into opening. The
actual sizes of doors, windows
and ventilators shall not vary
by more than 1.5 mm form
those given in drawing.
Fabrication: Both the fixed and opening frames are constructed of sections
which have been cut to length and mitered. The corners of fixed and opening
frames are welded to form a solid-fused welded joint conforming to the
requirements given below. All frames are square and flat. The process of
welding adopted may be flash or butt welding or any other suitable methodwhich gives the desired results.
Requirements of welded joints: Visual inspection test: when two opposite
corners of the frame are cut, paint removed and inspected, the joint shall
conform to the following:
(i) Welds should have been made all along the place of meetingmembers.
(ii) Welds should have been properly ground, and(iii) Complete cross section of the corner is checked up to see that
the joint is completely solid and there is no cavity visible.
Mi cro and macro examinations: From the two opposite corners obtained for
visual test, the flanges of the sections are cut with the help of a saw. The cut
surfaces of the remaining portions are polished, etched and examined. The
polished and etched faces of the weld and the base metal is free from cracks
and fairly free from under cutting, overlaps, gross porosity and entrapped
slag.
Fillet weld test: The fillet weld in the remaining portion of the joint obtained
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is fractured by hammering. The fractured surfaces are free from slag porosity,
crack, penetration defects and fusion defects.
Door: The hinge pin is of electro-galvanized steel of suitable thickness and
size. In case of double doors, the first closing leaf is the left hand leaf lockingat the door from the push side. The first closing shutter shall have a
concealed steel bolt at top and bottom. The bolts are so constructed as not to
work loose or drop by their own weight. Single and double shutter door is
provided with a three way bolting device.
Windows: For fixed windows the frames are fabricated as described in
fabrication. But side hung windows for fixing steel hinges slots are cut in the
fixed frame and hinges inserted inside and welded to the frame. The hinges
are of projecting types the hinge pin is of galvanized steel.
Friction hinges are provided for side hung windows shutters if specified. The
handle plate is welded, screwed or riveted to the opening frame in such amanner that it should be fixed before it is glazed and should not be easily
removable after glazing. The handles shall have a two point nose which shall
engage with a brass striking plate on the fixed frame in a slightly opened
position as well as in the closed position.
The boss of the handle shall incorporate a friction device to prevent handle
from dropping under its own weight and the assembly is so designed that the
rotation of the handle may not cause it to unscrew from the pin. The strike
plate is so designed and fixed in such a position in relation to the handle that
with the latter bearing against it stops; there is adequate light fit between
casement and outer frame. In case where nonfriction type hinges are
provided, the windows are fitted with peg stags which are either of blackoxidized steel or as specified, 300 mm long with steel peg and locking
brackets. The pegs stays have three holes to open the side hung casement in
three different angles. Side hung casement fitted with friction hinges is not
provided with a peg stay.
Galvanizing: All steel surfaces are thoroughly cleaned of rust, scale and dirt.
Where so specified, the steel surfaces are treated for rust-proofing by the hot
dip, zinc spray or electro-galvanizing process. The rate is exclusive of final
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finishing coats but shall include the priming coat.
Fixing: Where openings are flush and with a rendered finish a clearance of
1.25 cm is provided between the steel frame and opening. In the case of
external masonry finish Fair-Faced and with rebated jambs a minimum1.25 cm clearance between frame and opening is provided.
Plastering and
finishing
Cement
Plastering
Cement
plastering
with a
floating coat
of neat
cement
Cement is fresh Portland
cement and sand is medium
quality, cleaned, free from
organic matter or salts. All the
materials including water are of
standard specification.
Preparation of mortar: Thematerials are at first mixed dry
thoroughly till uniform in
colour in the required
proportion and then is mixed
wet adding water slowly and
gradually for at least four times
to give a uniform paste. Only
as much material is prepared at
a time as can be used within the
initial setting time (30 minutes)
of cement.
Cement is fresh Portland
cement and sand is medium
quality, cleaned, free from
organic matter or salts. All the
materials including water are of
standard specification
Preparation of surface: The surface of the wall is brushed, cleaned, washed,
watered and wetted with water before plastering. In case of cement plaster on
cement concrete the face is lightly roughened, cleaned, washed and wetted.
To ensure uniform thickness of plaster as specified, narrow strips of about 10
cm wide plaster is applied first a distance of about 1 m centres and the gaps
between such strips shall immediately be filled up with mortar.
Laying: The plastering is started from the top and worked towards theground. The whole surface is made flush with wooden straight edges and
rubbed thoroughly with wooden floats to ensure an even surface. Rounding
of corners if desired by the Engineer-in-Charge is carried out in one operation.
Curing: Plastering surface is kept wet by sprinkling water after 12 hours for
at least 7 days and is protected from rain or sun.
State the specification of cement plaster except for the additional floating
coat which is carried out as below:
When the plaster has been brought to a true surface with wooden straight
edge it is uniformly treated over its entire area with a paste of neat cement
and rubbed smooth, so that the whole surface is covered with neat cement
coating. The quantity of cement applied for floating coat is 1.0 kg per sq m.
Smooth finishing is completed with trowel immediately and in no case later
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6 mm thick
cement
plaster in
ceiling
than half an hour of adding water to the plaster mix.
(Note: The floating coat may be of red-oxide. In that case 3.5 kg of red oxide
to 50 kg of cement if not otherwise mentioned is mixed dry and is applied at
the rate of 1.0 kg