SPECIFICATION
1) Draft specification for IInd Class B.B.M. in 1:6 cement mortar.
1. In case of II class brickwork, bricks shall be of second class
and mortar shall be as specified cement mortar of 1:6
proportion.
2. Mortar joints shall not be more than 10mm in thickness. Bricks
shall be soaked in water for at least three hours before use.
a) Material of bricks:
1. The bricks shall be table moulded, well burnt, copper coloured,
free from any cracks fissures and defects and with sharp edges.
3. The bricks shall be of uniform shape and size. When two bricks
struck with each other, bricks should give clear ringing sound.
4. The crushing strength or compressive strength of brick shall not
be less than 10.5 N/mm2
5. The bricks shall not absorb water more then one fifth of their
weight when soaked in water for one hour.
b) Mortar:
1. The brick work shall be worked in cement mortar and mixing
of cement, sand and water shall be as per the specified
proportion. In case of wet sand, its quantity shall be increased
suitably so as to allow for bulkage.
2. In case of cement mortar the unit of measurement shall be a
bag of cement (0.035 cu.m.) Sand shall be measured in boxes
of suitable size 35cm 25cm 40cm as per the specified
proportion.
c) Mixing:
1. Materials of mortar shall be first mixed without water until a
uniform colour is obtained. The mixing shall be done on a
clean water tight platform. After addition of required fresh
potable water, the mixture shall be mixed at least three times
with the help of spade. Only the quantity of cement mortar
which can be used within 30 minutes shall be prepared at a
time.
2. The bricks shall be well soaked in water for at least 3 hours
before their use.
3. The broken bricks shall not be used except as closer. The
mortar joints shall break for bonding and good key and shall
not be more than 10mm in thickness.
4. Bricks shall be laid with frogs upward, except in the top
course. Brickwork shall not be carried out more than 1m in
height at a time. All joint shall be raked and faces of wall shall
be cleaned at the end of each days work.
5. The brickwork shall be cured for at least 15 days.
6. For all exposed brickwork, double scaffolding shall be used.
For all other brickwork in building, single scaffolding shall be
permitted
d) Measurement:
The length and height shall be measured as on at site. The
thickness of walls shall be paid for as one brick, one and a half
bricks, two bricks in cu.m
2) Draft a detailed specification for UCR masonry work in CM
(1:4) for foundation work.
The Detailed specification for UCR Masonry can be divided as
i) Materials ii) Mortar iii) Laying iv) Measurement
(i) Materials :
(a) Stone :
Stone shall be hard, able to dress, sound, free from decay,
defect and weathering.
Stones with pores and defects shall be rejected.
Size of stone shall not be less than 150 mm in any
direction.
Stones will be dressed and brought to required size and
shape.
Stones with rounded surface shall not be used for the work
(b) Sand or fine aggregate :
Sand or find aggregate needed for mortar shall be as per the
standard specification. Sand shall be well graded and sized,
clean and free from dust ,dirt, and organic matter foreign
matter
(c) Cement :
Cement for mortar shall be as per the standard specification.
It shall be fresh shall be of uniform color and free from
lumps. If doubtful it shall be checked and subjected to tests
and used only after found satisfactory
d) Water
water fit for drinking purposes shall be used for construction
purpose
(ii) Mortar :
Various ingredients of mortar shall be first mixed in
prescribed proportion of 1: 4 with measuring box and first
mixed dry to have uniform colour on water tight platform
and then mixed wet at least three times by adding water
evenly and gradually in appropriate proportion as specified.
(iii) Laying :
The foundation trench shall be clean properly and
sprinkled with water
1)All the dressed stones shall be wetted thoroughly
before laying in stone work. The walls shall be carried
up in line and truly plumb.
2) Face stone shall not be narrower than that of its height
shall tail back and bond well into backing .
3)Stones shall be laid with break joint on the face for at
least half the height with those of courses above or
below.
4)All joints after laying the stones shall be filled by
mortar completely and thickness of joint shall not
more than 20 mm.
5)So as to prevent thick beds of joints and mortar,
interstices between stones shall be filled with stone
chips and spalls.
6)Bond stones at least 450 mm long shall be given one
for every half sq.m face in the interior thickness of the
walls.
7) Through stones (H) shall be approximately provided
so as to have the key bonding in between facing and
backing.
8)The masonry wall shall be carried out together with a
line and truly plumb so as to have uniform height.
iv) Measurement of stone work :
Measurement of UCR masonry shall be taken in cu.m.
3)Draft a detailed specification for internal Painting with 3
coats of dry distemper
1)Cleaning
The surface to be painted shall be cleaned and made smooth by
rubbing sand papers of different grades cracks loose plaster shall
be bought up by plaster work and all the holes and undulations
shall be filled up with plaster of Paris and rubbed smooth
2)Distempering
The distemper shall be of best quality and the color should be as
specified. The distemper should be mixed and prepared and
water added as laid down in the instruction of the manufacturers.
First a paste is made by adding little hot water to the distemper
powder and stirred thoroughly and the paste is allowed to stand
for a few minutes. The paste is thinned with water and stirred
thoroughly all the time The surface must be perfectly dry before
distempering is to be started. In new cement plaster the surface
shall be washed over with a solution of zinc sulphate. In old
surface the surface shall be repaired with plaster of Paris where
required and then whole surface shall be washed and allow to dry
Coating
the number of coats shall be two or three as specified,The
distemper shall be kept well in stirred in containers and shall be
applied with broad brushes first horizontally and immediately
crossed vertically .Brushing should not be too long to avoid
brush marks The second coat shall be applied after first and coat
is dried up and after this final coat shall be applied Distempering
should be carried out during dry weather but nor during too hot
and wet weather
3) Workmanship
The distemper shall be applied in the best workmanship manner
the brushes shall be of best quality and they shall be worked in
such manner that a surface of uniform shade is obtained without
any hair crack drops etc. after each days of work brushes shall
be washed and kept dry.
4) Measurement
Distempering shall be taken in Sq.m stating number of coats and
measurement shall be taken flat
4)Draft a detailed specification for external plastering in cm (1: 4)
with 20 mm thickness of a new brick wall.
(i)Material:
Cement: Ordinary Portland cement shall be used .The cement shall
conform to IS: 269 latest versions.
Sand: Fine aggregate shall be natural sand obtained from a river bed
and shall conform to 15:383-1 and to the relevant portion of IS: 515
1959. Sand shall be clean, hard, strong, durable and free from organic
matter, dust, clay, shale, alkali, salts, soft or flaky particles or other
injurious substances.
Water: Potable water shall be used for mixing the mortar.
(ii)Proportion: Cement and sand shall be mixed in the proportion of
one part of cement to four parts of sand.
Mixing: Mortar shall be mixed in a mechanical mixer of an approved
pattern at the site of work The drum shall be rotated for a minimum
period of 2 minutes The mortar shall be used within 30 minutes of
adding water or by hand mixing
(iii)Plastering: The mortar shall be firmly applied on the surface from
top to down and well pressed into the joints. The mortar shall then be
rubbed and leveled with a flat wooden rule until a perfectly plane and
even surface is achieved. All corners shall be finished to their angles,
unless otherwise directed by the engineer: The jambs and reveals Of
door and window openings shall be finished perpendicular to the sill
and lintel bottom. Plastering shall be done in squares or strips as
directed by the engineer. Strips or squares shall be so formed that day
to-day breaks are made to coincide with architectural breaks.
Finish: While the plastered surface is fresh, a thick coat of cement
slurry shall be applied and rubbed smooth.
Curing: All plastered surfaces shall be kept continuously damp for -a
period of 14 days.
(iv)Mode of Measurements: The unit of measurement shall be the
square meter as per IS: 1200.
5) Draft detailed specification for pcc foundation bed in cement
concrete 1:2:4.
Specification of cement concrete for PCC work includes the
following items:
(i) Materials:
(a) Course aggregate:
Coarse aggregate shall be from hard broken stone of compact
basalt or granite or similar stone and shall be free from dust, dirt,
oil and other foreign matters.
Size of stone shall be 20 mm and down and all sizes of stones shall
be retained in a 5 mm square mesh and well graded, shall not have
voids more than 42%.
Size of stone aggregate depends upon the thickness of concrete
and nature of work.
For example, 20 mm size of stone aggregates are being used for
building work and road work. 40 to 60 mm size of coarse
aggregate are being used for mass concreting work.
(b) Fire aggregate:
1)Fine aggregate shall have coarse sand consisting of hard,
sharp and angular grains.
2) These aggregates shall pass through sieve of 5 mm square
mesh.
3) Sand shall be as per the standard specification.
4)Sand shall be clean and free from dust, dirt, oil and other
organic matter.
5) Sea sand shall not be used.
6)Crushed stone sand can also be used if specified.
(c) Cement:
Cement shall be fresh, not old and as per the standard I.S.
specification and shall have required compressive strength and
fineness.
(d) Water:
Water shall be clean water, free from any impurities and free
from alkaline and acid matters; water shall be suitable for
drinking purpose.
(ii) Proportion:
1. The proportion of concrete shall be 1:2:4 of
cement, sand and course aggregate by volume unless otherwise
specified.
2. For 7 days, the minimum compressive strength of cement
concrete (1:2:4) shall be 14 N/mm2.
3. One bag of cement consist of 50 kg should be considered as
cu.m. No need to measure the cement by box or Formica, but
sand and coarse aggregate shall be measured by volume with
boxes or Formica. Box size may be 35 cm 35 cm
28 cm or 30 cm 30cm 38 cm equivalent to the content of one
bag of cement.
4. All ingredients shall be dry. Bulking of sand allowance shall be
made for wet sand.
5. For large work, mixing of ingredients shall be machine mixing
and for small work, mixing shall be done by hand mixing by
batches may be permitted.
Machine Mixing:
1. Cement, sand and coarse aggregate shall be taken into the
machine mixer in required proportion.
2. For concrete of proportion 1:2:4 consist of one bag of cement,
two boxes of sand and four boxes of coarse aggregate shall be
taken into mixer.
3. The machine shall then be operated to mix material dry & then
water shall be added gradually with required quantity 25 to 30
liters of water per bag of cement to obtain the desired water
cement ratio.
4. The mixing should have homogeneous mass or plastic mix of
uniform colour so as to obtain thorough mixing 1.5 to 2 minutes
rotation shall be given to the drum mixer.
5. Mixed concrete shall be discharge on a masonry platform or on a
flat iron sheet.
Hand Mixing:
1. Hand mixing is allowed for small work only. Mixing of
ingredients shall be done on masonry platform or flat iron sheet.
2. For concrete of 1:2:4/1:4:8 proportion, one bag of cement, first
two boxes of sand shall be mixed dry thoroughly making the
material turning up and down by spade or phawarha and then
this homogeneous dry mix shall be placed over a spreaded stack
of 4 boxes of coarse aggregate & the complete mixed dry turn up
and down with phawarha or spade at least three times so as to
obtain uniform mix. Then water shall be added slowly and gradually
and then turning the mix up and down at least three times by spade
till to obtain a plastic mix of the required workability and water –
cement ratio.
3. Water quantity shall be of 25 to 30 liters per bag of cement.
(iii) Slump test:
Regular slump test shall be carried out so as to check the
workability of concrete mix and to control the addition of water.
For building work, a slump of 75 mm to 100 mm may be
permitted and for road work, 30 mm to 40 mm may be allowed.
(iv) Form work:
Form work and centering shall be used as per the standard
specifications‟
Internal surface of formwork shall be applied by oil so as to
avoid sticking of concrete during removal of the formwork.
The base of formwork shall be watered before laying the
concrete on it.
Forms at the bottom surface in case of beam and slab shall not be
removed before 14 days in general and sides of form shall be
removed after 3 days.
Form work shall be removed slowly and with care and not to
disturb and damage the concrete.
(v) Laying of concrete:
Concrete shall be laid gently in layers not exceeding 150 mm
and compacted with rods & tamping with wooden tampers or
with mechanical vibrating machine until a dense concrete is
obtained.
Immersion type vibrators or needle vibrators shall be used for
thick concrete or mass concrete. Surface vibrators or form
vibrators shall be used for thin concrete. There shall not be over
vibration.
Concrete shall be laid continuously. If laying of concrete is
suspended for rest or on next day
the end of concrete shall be slope with an angle of 30 and its
surface shall be made rough for proper joining.
If the concreting work is resumed, the previous sloped portion
shall be made rough, clean, watered and a grout of neat cement
shall be applied and fresh concrete shall be laid in successive
layer in such way that the upper layer shall be laid before the
lower layer is set.
(vi) Curing:
When concrete is on the point of hardening, after and about two
hours laying, then it shall be kept wet by covering with wet
gummy bags for 24 hours and then cured by flooding with water.
Making mud wall 75 mm high or by covering with wet sand
continuously for 15 days.
In case of flat concrete work like slabs, the ponding method of
curing shall be used.
Measurement:
The measurement shall be taken as per the dewing or as per
instruction of the engineer.
6)Draft detailed specification for P.C.C. Assume suitable mix.
Specification of cement concrete for PCC work includes
(i) Materials :
(a) Course aggregate :
i. Coarse aggregate shall be from hard broken stone of compact
basalt or granite or similar stone and shall be free from dust,
dirt, oil and other foreign matters.
ii. Size of stone shall be 20 mm and down and all sizes of stones
shall be retained in a 5 mm square mesh and well graded.
iii. Size of stone aggregate depends upon the thickness of concrete
and nature of work.
b) Fine aggregate :
i. Fine aggregate shall have coarse sand consisting of hard, sharp
and angular grains.
ii. Sand shall be as per the standard specification.
iii. Sand shall be clean and free from dust, dirt, oil and other
organic matter.
c) Cement :
Cement shall be fresh, not old & as per the standard I.S.
specification and shall have required compressive strength and
fineness.
(d) Water :
Water shall be clean water, free from any impurities and free
from alkaline and acid matters; water shall be suitable for
drinking purpose.
(ii) Proportion :
The proportion of concrete shall be 1:2:4 of cement, sand and
course aggregate by volume unless otherwise specified.
For 7 days, the minimum compressive strength of cement
concrete (1:2:4) shall be 14 N/mm2 .
All ingredients shall be dry. Bulking of sand allowance shall
be made for wet sand.
Machine Mixing :
Cement, sand and coarse aggregate shall be taken into the
machine mixer in required proportion.
For concrete of proportion 1:2:4 consist of one bag of cement,
two boxes of sand and four boxes of coarse aggregate shall be
taken into mixer.
Mixed concrete shall be discharge on a masonry platform or on
a flat iron sheet.
Hand Mixing :
Hand mixing is allowed for small work only. Mixing of
ingredients shall be done on masonry platform or flat iron sheet.
For concrete of 1:2:4/1:4:8 proportion, one bag of cement, first
two boxes of sand shall be mixed dry thoroughly making the
material turning up and down by spade and then this
homogeneous dry mix shall be placed over a spreaded stack of 4
boxes of coarse aggregate & the complete mixed dry turn up and
down with spade at least three times so as to obtain uniform
mix. Then water shall be added slowly and gradually and then
turning the mix up and down at least three times by spade till to
obtain a plastic mix of the required workability and water –
cement ratio.
Water quantity shall be of 25 to 30 liters per bag of cement.
(iv) Form work :
Form work and centering shall be used as per the standard
specifications‟
Internal surface of formwork shall be applied by oil so as
to avoid sticking of concrete during removal of the
formwork.
(v) Laying of concrete :
Concrete shall be laid gently in layers not exceeding 150
mm and compacted with rods & tamping with wooden
tampers or with mechanical vibrating machine until a
dense concrete is obtained.
Immersion type vibrators or needle vibrators shall be used
for thick concrete or mass concrete. Surface vibrators or
form vibrators shall be used for thin concrete. There shall
not be over – vibration.
Concrete shall be laid continuously. If laying of concrete is
suspended for rest or on next day
the end of concrete shall be slope with an angle of 30 and
its surface shall be made rough for proper joining.
If the concreting work is resumed, the previous sloped
portion shall be made rough, clean, watered and a grout of
neat cement shall be applied and fresh concrete shall be
laid in successive layer in such way that the upper layer
shall be laid before the lower layer is set.
(vi) Curing :
When concrete is on the point of hardening, after and
about two hours laying, then it shall be kept wet by
covering with wet gummy bags for 24 hours and then
cured by flooding with water. Making mud wall 75 mm
high or by covering with wet sand continuously for 15
days.
vii) Measurement :
The measurement shall be taken as per the drawing or as per instruction of the
engineer.
7)Draft the detailed specification for M20 grade of concrete in
footing and column.
1. Proportion: Proportion of 1: 1.5: 3 shall be adopted by taking one
part of cement, 1.5 parts of sand or fine aggregates and three parts of
coarse aggregate by volume.
2. Concrete Ingredients:
Cement: Cement shall be measured by weight as per the standard
requirements.
Fine Aggregate: The sand shall be free from impurities like dust,
clay, oil etc. It shall be well washed before use.
Coarse Aggregate: The coarse aggregate shall consist of 67% of size
from 20mm to 40mm and 33% size from 20mm to 6mm. The coarse
aggregate shall also be free from impurities like clay, dust, oil and
organic material.
Water: The water shall be clean, fresh and drinkable.
3. Steel: Steel reinforcing bars used in concrete shall be of mild steel
or deformed steel as per the standard specifications and shall be free
from corrosion, loose rust scales, paint, grease, oil etc. Joints in the
bar shall be prevented. When joints have to be made, then an overlap
of 40 times diameter of the bar shall be given. Bigger diameter bars
shall be joined by welding. Proper cover shall be maintained for steel
bars, so as to prevent from exposing to atmosphere.
4. Concreting Operations:
Mixing: The mixing of concrete shall be done in a mechanical mixer
for large scale concrete or by hand operation for small scale concrete
work.
Form work: The formwork shall be oiled from inside before
concreting the formwork. The concrete shall be laid in the forms and
tapped in such manner that no honeycomb surface shall appear onremoval of the
forms.
The formwork and centering shall be made of dressed timber of well
seasoned wooden boards to give a smooth and even surface and the
joints shall not allow leakage of cement paste.
Laying of concrete: Concrete shall be laid continuously, if laying is
suspended for rest, then end shall be sloped at an angle of 30 and
made rough for proper bonding and key. When the work is resumed,
the previous sloped portion shall be made rough, clean and watered. A
coat of neat cement paste shall be applied on this roughened portion
and fresh concrete shall be laid.
Compaction: Concrete shall be compacted by mechanical vibrators so
as to have a dense concrete. Over-vibration shall be prevented.
Hand compaction shall be done with the help of punning rods and
tamping rods and tamping with the wooden tampers so that concrete is
thoroughly compacted and completely walked into the corners of the
form work.
After removal of the form work, the concrete surface shall be free
from any defects such as honey combing, air holes, cracks etc.
Curing: Freshly laid concrete shall be protected from direct sun, rain
etc. When the concrete is set or harden about 2 hours after its laying, it
shall be protected with gunny bags.
After 24 hours of laying; the concrete surface shall be cured by
flooding with water by making small ponds. The minimum period for
curing shall be 14 days.
5. Measurement: Length, breadth and depth or thickness shall be
measured correct to a cm and the consolidated cubic contents of the
concrete shall be calculated net to the nearest 0.01 cubic meter.
Concrete laid in excess of the dimensions shown in the drawings shall
not be measured.
8) Draft detailed specification of cement concrete (M 20 )for slab &
beam.
Specification of cement concrete for PCC work includes-
(i) Materials :
(a) Course aggregate :
Coarse aggregate shall be from hard broken stone of compact basalt
or granite or similar stone and shall be free from dust, dirt, oil and
other foreign matters.
Size of stone shall be 20 mm and down and all sizes of stones shall be
retained in a 5 mm square mesh and well graded.
Size of stone aggregate depends upon the thickness of concrete and
nature of work.
b) Fine aggregate :
Fine aggregate shall have coarse sand consisting of hard, sharp and
angular grains.
Sand shall be as per the standard specification.
Sand shall be clean and free from dust, dirt, oil and other organic
matter.
c) Cement :
Cement shall be fresh, not old & as per the standard I.S. specification
and shall have required compressive strength and fineness.
(d) Water :
Water shall be clean water, free from any impurities and free from
alkaline and acid matters; water shall be suitable for drinking purpose.
ii) Reinforcement: It shall be of mild steel free from corrosion .All
bars shall be made and placed as per bar schedule & design. Proper
overlapping shall be provided.
iii) Proportion :
The proportion of concrete shall be such that it should give strength of
at least 20 N/mm2 .1: 1.5:3 proportion of cement, sand and course
aggregate by volume shall be used, unless otherwise specified.
All ingredients shall be dry. Bulking of sand allowance shall be made
for wet sand.
iv) Mixing of concrete
a)Machine Mixing :
Cement, sand and coarse aggregate shall be taken into the mixer in
Required proportion.
The mixing time shall not be less than 3 minutes
Mixed concrete shall be discharge on a masonry platform or on a
Flat iron sheet.
b)Hand Mixing :
Hand mixing is allowed for small work only. Mixing of ingredients
shall be done on masonry platform or flat iron sheet.
Then water shall be added slowly and gradually and then turning the
mix up and down at least three times by spade till to obtain a plastic
mix of the required workability and water – cement ratio.
v) Form work/Centering :
Form work and centering shall be used as per the standard
specifications Internal surface of formwork shall be applied by oil so
as to avoid sticking of concrete during removal of the formwork.
vi) Laying of concrete :
Concrete shall be laid gently and compacted with rods & tamping
with wooden tampers or with mechanical vibrating machine until a
dense concrete is obtained.
Immersion type vibrators or needle vibrators shall be used for thick
concrete or mass concrete. Surface vibrators or form vibrators shall be
used for thin concrete. There shall not be over – vibration.
Concrete shall be laid continuously.
(vii) Curing :
When concrete is on the point of hardening, after and about two hours
laying, then it shall be kept wet by covering with wet gunny bags for
24 hours and then cured by flooding with water. Making mud wall 75
mm high or by covering with wet sand continuously for 15 days
(viii) Measurement :
The measurement shall be taken as per the drawing or as per
instruction of the engineer. The measurement shall be in cubic meter
without deducting volume of steel. The rate of RCC shall be for the
complete item which include shuttering ,tools & plants .The
measurement shall confirm IS 1200
9) Draft detailed specification for RCC slab 1:2:4.
Specification of cement concrete for PCC work includes:
(i) Materials:
a) Coarse aggregate:
Coarse aggregate shall be from hard broken stone of compact basalt
or granite or similar stone and shall be free from dust, dirt, oil and
other foreign matters.
Size of stone shall be 20 mm and down and all sizes of stones shall be
retained in a 5 mm square mesh and well graded.
Size of stone aggregate depends upon the thickness of concrete and
nature of work.
b) Fine aggregate:
Fine aggregate shall have coarse sand consisting of hard, sharp and
angular grains.
Sand shall be as per the standard specification.
Sand shall be clean and free from dust, dirt, oil and other organic
matter.
c) Cement :
Cement shall be fresh, not old & as per the standard I.S. specification
and shall have required compressive strength and fineness.
d) Water :
Water shall be clean water, free from any impurities and free from
alkaline and acid matters; water shall be suitable for drinking purpose.
ii) Reinforcement: It shall be of mild steel free from corrosion .All
bars shall be made and placed as per bar schedule & design. Proper
overlapping shall be provided.
iii) Proportion :
The proportion of concrete shall be such that it should give strength of
at least 20 N/mm2 .1:2:4 proportion of cement, sand and course
aggregate by volume shall be used, unless otherwise specified.
All ingredients shall be dry. Bulking of sand allowance shall be made
for wet sand.
iv) Mixing of concrete:
a)Machine Mixing :
Cement, sand and coarse aggregate shall be taken into the mixer in
required proportion. The mixing time shall not be less than 3 minutes
Mixed concrete shall be discharge on a masonry platform or on a
flat iron sheet.
b)Hand Mixing :
Hand mixing is allowed for small work only. Mixing of ingredients
shall be done on masonry platform or flat iron sheet. Then water shall
be added slowly and gradually and then turning the mix up and
down at least three times by spade till to obtain a plastic mix of the
required workability and water–cement ratio.
v) Form work/Centering :
Form work and centering shall be used as per the standard
specifications Internal surface of formwork shall be applied by oil so
as to avoid sticking of concrete during removal of the formwork.
vi) Laying of concrete :
Concrete shall be laid gently and compacted with rods and tamping
with wooden tampers or with mechanical vibrating machine until a
dense concrete is obtained.
Immersion type vibrators or needle vibrators shall be used for thick
concrete or mass concrete. Surface vibrators or form vibrators shall be
used for thin concrete. There shall not be over vibration.
Concrete shall be laid continuously.
(vii) Curing :
When concrete is on the point of hardening, after and about two hours
laying, then it shall be kept wet by covering with wet gunny bags for
24 hours and then cured by flooding with water. Making mud wall 75
mm high or by covering with wet sand continuously for 15 days.
(viii) Measurement :
The measurement shall be taken as per the drawing or as per
instruction of the engineer. The measurement shall be in cubic meter
without deducting volume of steel. The rate of RCC shall be for the
complete item which includes shuttering, tools and plants. The
measurement shall confirm IS 1200.
10) Give the detailed specification for R.C.C slab for M25.
Specification of cement concrete for RCC work includes-
(i) Materials :
(a) Course aggregate : Coarse aggregate shall be from hard broken
stone of compact basalt or granite or similar stone and shall be free
from dust, dirt, oil and other foreign matters. Size of stone shall be 20
mm and down and all sizes of stones shall be retained in a 5 mm
square mesh and well graded. Size of stone aggregate depends upon
the thickness of concrete and nature of work.
b) Fine aggregate :
Fine aggregate shall have coarse sand consisting of hard, sharp and
angular grains. Sand shall be as per the standard specification. Sand
shall be clean and free from dust, dirt, oil and other organic matter.
c) Cement :
Cement shall be fresh, not old & as per the standard I.S. specification
and shall have required compressive strength and fineness.
(d) Water :
Water shall be clean water, free from any impurities and free from
alkaline and acid matters; water shall be suitable for drinking purpose.
ii) Reinforcement:
It shall be of mild steel free from corrosion .All bars shall be made
and placed as per bar schedule & design. Proper overlapping shall be
provided.
iii) Proportion :
The proportion of concrete shall be such that it should give strength of
at least 20 N/mm2 .1: 1.5:3 proportion of cement, sand and course
aggregate by volume shall be used, unless otherwise specified.
All ingredients shall be dry. Bulking of sand allowance shall be made
for wet sand.
iv) Mixing of concrete
a)Machine Mixing :
Cement, sand and coarse aggregate shall be taken into the mixer in
Required proportion. The mixing time shall not be less than 3 minutes
Mixed concrete shall be discharge on a masonry platform or on a Flat
iron sheet.
b)Hand Mixing :
Hand mixing is allowed for small work only. Mixing of ingredients
shall be done on masonry platform or flat iron sheet. Then water shall
be added slowly and gradually and then turning the mix up and down
at least three times by spade till to obtain a plastic mix of the required
workability and water – cement ratio.
v) Form work/Centering :
Form work and centering shall be used as per the standard
specifications Internal surface of formwork shall be applied by oil so
as to avoid sticking of concrete during removal of the formwork.
vi) Laying of concrete :
Concrete shall be laid gently and compacted with rods & tamping
with wooden tampers or with mechanical vibrating machine until a
dense concrete is obtained. Immersion type vibrators or needle
vibrators shall be used for thick concrete or mass concrete. Surface
vibrators or form vibrators shall be used for thin concrete. There shall
not be over – vibration. Concrete shall be laid continuously.
(vii) Curing :
When concrete is on the point of hardening, after and about two hours
laying, then it shall be kept wet by covering with wet gunny bags for
24 hours and then cured by flooding with water. Making mud wall 75
mm high or by covering with wet sand continuously for 15 days
(viii) Measurement :
The measurement shall be taken as per the drawing or as per
instruction of the engineer. The measurement shall be in cubic meter
without deducting volume of steel. The rate of RCC shall be for the
complete item which include shuttering ,tools & plants .The
measurement shall confirm IS 1200
