11 GENRAL NOTES FOR CIVIL ENGINEERING AND | 11 IMPORTANT BULLETS POINTS IN CIVIL SITE KNOWLEDGE |
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| 11 BULLETS & 11 GENRAL POINTS |
* 11 GENRAL NOTES FOR CIVIL ENGINEERING :-
1. Electrical conduits shall not run in column.
2. Earth work excavation for basement above 3 m Should be Stepped form.
3. Any Back filling shall be compacted 95% of dry density at the Optimum moisture content and in layers not more than 200mm For filling above structure and 300 mm for no structure.
4.
f
soling is specified the soling stones shall be laid At45° to 60° inclination
(and not vertical) with Interstices filled
with sand or moorum.
5.
Y represents tor steel grade - fe-415 of
is:1786. With Charecteristic yield strength of 415 n/mm minimum.
6.
∅ represents mild steel grade - 1
of is:432 (part-1)
7.
All reinforcement shall be free from mill
scales, Loose rust & coats of paints, oil or any other
Substances.
8.
By providing proper cover blocks, spacers,
chairs Etc.. All reinforcement shall be placed and Maintained in position as
shown in structural Drawing.
9.
Cement shall be 43 grade ordinary portland
cement Conforming to is:8112 or53 grade ordinary portland Cement conforming to
is:12269-1987.
10.
Cement shall be stored in dry places on a raised
Platform about 200mm above floor level
and 300mm Away from walls. Bags to be stacked not more than 10 bags high in
such a manner that it is adequately Protected from moisture and contamination.
11.
Water used for both mixing and curing shall be Clean
and free from injurious amounts of oils, acids, Alkalis, salts, sugar and
organic materials or Other substances that may be deleterious to Concrete or
steel. The ph shall be Generally between
6 and 8.
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| CIVIL SITE KNOWLEDGE |
* 11 IMPORTANT BULLETS POINTS IN CIVIL SITE KNOWLEDGE:-
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| BULLETS POINTS |
1. CONCRETE
COVER:-
Ø *CLEAR COVER TO MAIN REINFORCEMENT
Footings : 50 mm
Ø
Raft foundation top : 50 mm
Ø
Raft foundation bottom/sides : 75 mm
Ø
Strap beam : 50 mm
Ø Slabs : 25 mm
Ø
Grade slab : 20 mm
Ø
Column : 40 mm
Ø
Shear wall : 25 mm
Ø
Beams : 25 mm
Ø
Flat slab : 20 mm
Ø
Staircase : 15 mm
Ø
Ret. Wall : 20/ 25 mm On earth
Ø
Water retaining structures : 20 / 30 mm.
Ø
contractor shall allow for independent testing
of Reinforcement steel for each dia of bar for every 50T and at Change of source
.
Ø All beam reinforcement To be anchored for a
minimum length of 46 x Dia of bar into column / supporting beam u.n.
Ø
Binding wires shall be 16 guage 1.6mm soft
annealed steel Wires free from rust and other contaminants.
*CONCRETE
MIX DESIGN REPORT.
Ø Concrete design mix report along with the Test results for concrete cubes shall be submitted
in advance for approval before Relevant concreting. And the minimum Cement
content shall be not less than 300 Kg/m
Ø
Slump shall be 100 + 25mm.
*POURING OF
CONCRETE.
Ø
No concreting operation shall be carried out
during Inclement weather conditions like heavy rain,
storm and High winds.
2.REPAIRS:-
Ø Concrete floor screed shall be in panels of 3m x 3m with joints sealed with sealant to match with joints in slab. Locations to be approved by engineer prior to concreting.
Ø Construction joint in retaining walls & water tank shall be provided with an approved sealant.
Ø All deeper excavation below the ground level slab shall be retained by a localized soil and water retention system, as may be retained by a localized and water retention system, as may be soil and water retention system as may be.
Ø Dewatering by suitable means to be adopted (ensuring no fines are drawn out) to keep the founding strata completely dry and shall be continued until the ground floor slab / beams are cast and cured to achieve specified design strength.
Ø Cement proportion: concrete mix in above such foundations shall contain 10 percent extra cement than specified.
Ø At locations of isolation / expansion joint provide polysulphide sealant with backer rod polystyrene boards.
Ø No through bolts shall be used in formwork of retaining wall. And water tank walls.
3.FOUNDATIONS:-
Ø all loose pockets and soft spots are to be filled in mass concrete of grade m-10.
Ø back filling behind the retaining wall shall be carried out only after the ground floor slab is cast and has attained design strength.
Ø the space between hard strata (to achive a minimum of 25 mt/m2) and bottom of raft/ foundation shall be filled with plum concrete.
Ø size stone masonry shall be in cm 1:6 unless specified otherwise.
Ø Continuous wall foundation shall be stepped in a ratio of 1 vertical to 2 horizontal wherever level changes are necessary.
Ø sloped portion to be finished smooth with trovel without using mortar. Column portion to be finished smooth with concrete.
Ø grade of concrete shall be as per footing shedule/ raft details.
Ø 4.SUPER STRUCTURE:-
All exposed corners of columns and beams shall have straight edges and shall be champhered if specified in architectural drawings.
Ø concreting of columns , beams, facias, and thin sections of concrete members shall be carried out using approved plasticiser as per manufacturers specifications.
Ø concrete pouring , testing, removal of formwork
and acceptance criteria shall be as per relevant indian standard code of
practice.
Ø Centering of cantilever beams and slab
projections shall not be removed unless roof slab above is cast and cured and
sufficient balancing load is attained. Provide pre camber to cant. Beams/slabs.
Ø Before pouring floor level concrete, the floor
systems below shall be sufficiently supported by means of propping and this
system shall be approved by the engineer-in-charge.
Ø Concrete in toilet, kitchen, water body areas
shall be mixed with approved waterproof compound and waterproofing over slabs
and sides of walls shall be done as per architectural details.
Ø
Contractor shall check all the openings as per
architectural/service drawings and shall provide necessary trimming bars.no
additional opening shall be drilled in the structure unless approved.
Ø Concrete should be placed in thin layers which
can be effectively compacted as the placing proceeds say in 300mm.
Ø When casting columns, walls or beams of depth
700mm or more, a layer of rich cementmortar should be placed first. This is to
avoid accumulation of gravel in the bottom layer and to have a better bond
Ø Compaction of concerte shall be done by
mechanical vibrators. Proper care shall be taken to avoid seggregation and
honeycombing.
Ø contractor shall submit shop drawings including
bar bending schedule for approval prior to taking up of construction.
Ø the secondary beam bars shall be placed over
main beam bars when the depth of beams are same at junctions.
Ø short span steel shall be at bottom layer in two
way slab system and spacers bar, chairs to top steel shall be provided with
adequate cover.
Ø no splicing of bars shall be made at the point
of maximum tensile stresses.
Ø for splices of reinforcement, minimum lap length
for barsshall be 50 x dia of bar.
Ø not more than 1/3 of main reinforcement shall be
lapped at any section
.
Ø splices if un avoidable, must be located from
face of the column at not closer than twice the beam depth.
Ø splices in beams shall be contained by
additional stirrups at a spacing not exceeding 150mm over the entire length of
splices
.
Ø stirrups shall be closed type with ends hooked
at 135 with 10 x bar dia extension (but not less than 75mm).
Ø spacing of stirrups shall not exceed 200mm.
5. Columns:-
· Concrete mix shall be as per schedule of columns.
· P.v.c cover blocks to be used with prior
approval of engineer.
· Rings to be provided for full length of main
rods toprevent dislocation of main bars while concreting, at a spacing as
specified in the shedule.
· Ld shall be
M25 and above 46 x dia
· Column starter to be set by template and shall
beprovided with next higher grade of concrete mix of columns.
· Beam bottom levels are to be marked on column
rods and column to be stopped at thislevel to avoid extrashuttering of columns
below beam bottoms.
· Indicates columns continuing further
· Indicates columns stopping at this level
6.DESHUTTERING TIME:-
· In normal circumstances where ambient temp. Does
not fall below 15 c & where ordinary portland cement is used & adequate
curing is done. Following stripping time may deem
· To satisfy.
o Vertical formwork to columns, walls, beams - 16
to 24hrs
o Soffit formwork to slabs(props to be refixed immediately
after removal of formwork) - 3 days
o Soffit formwork to beams(props to be refixed
immediately after removal of formwork) - 7 days
Props to slabs:
§ Slabs spanning upto 4500 mm - 7 days
§
Slabs spanning over 4500 mm - 14 days
Props to beams and arches:
· Beams spanning upto 6000 mm - 14 days
· Beams spanning above 6000 mm -21 days
7.ROOF LEVEL CONCRETE :-
· Floor shuttering levels to be as per
architectural drawings. The shuttering should be levelled and contain no voids
to prevent slurry leakage. The external
shuttering to be more in height by 75 mm than required. Diagonals of each
rectangales / squares shall be checked.
· Reinforcement for slabs shown thus
· At top
· At bottom
· Distribution reinforcement for slab top rods
shall bey8@225cc unless specified otherwise in relevant drawingpin rods/chairs.
· Second layer and third layer reinforcement in
beams to be tied with pin rods of y20 / y25 only.
·
Chairs to be provided to support top
reinforcement in slabs using suitable dia bars with approval of
engineer-in-charge.
8.CONSTRUCTION JOINTS:-
· Construction joints in slabs and beams are often placed either at point of contra-flexture in which case the concrete may be left sloped off or stepped off by means of stop forms construction joints located near minimum shear shall have stop forms perpendicular to the acting forces. Where the concrete is to be placed in the second pour, the old concrete shall be thoroughly roughened to expose aggregates moistened and a layer of rich fresh mortar should be laid mmediately before fresh concrete is placed. It should be placed to a thickness of 20 to 30mm and shall be worked well into the irregularities of hardened concrete.
· All the construction joints shall be
pre-determined as per the sequence of operation and shall be got approved.
· Construction joints shall be in accordance with
typical construction joint details.
· Expansion joint detail shall be as per typical
expansion joint details.
9.CURING METHOD:-
· Curing of slabs and beams shall be achieved by ponding only, for a minimum period of 7 days.
· Curing of footing tops,rcc walls,columns and
external beam faces shall be done by covering them with gunny bags or hessian
and keeping wet constantly for complete curing period of 7 days.
· Groove cutting machine shall be used for chasing
of walls for all electrical conduits.
· 4" wide to 7" wide expanded metal mesh
shall be used before plastering of all conduit chasings in walls.
·
For column-wall junctions & beam-wall
junctions 4" wide expanded metal mesh shall be used, before plastering of
concrete and wall junctions.
10.WATER RETUNNING STRUCTURE:-
· Concrete mix m-25 shall be used for all water retaining structure with 330kg/cu.m of cement minimum.unless otherwise specified.
· Ditchtment d.m or conplast liquid admixture
shall be usedwith m-25 concrete at 150 ml per bag of cement.
· Plastering shall be done with c.m 1:4 using putz
ditchment d.m or conplast liquid admixture at 150ml per bag of cement.
11.Interior walls:-
- Darker shades may require an additional coat for proper hiding. The actual shade, especially for darker shades, can be observed only after the film is dry and not in the can or in the wet state.
- Felt rolling is to be done only for Royale and Lustre finish. The darker shades are never to be felt rolled since this will cause foaming due to presence of more surfactants in them.
- Solvent based paints (those using thinner other than water) should be given twice as long a drying time than given here in case of high humidity climate like monsoon.
- Putty can be applied to make the substrate smoother; however it has to be sandwiched 2 coats of primer.
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