BACKFILLING IN SIDES OF FLOORS, PLINTH, UNDER FLOOR ETC..
The backfilling shall be done after the concrete or masonry has fully set and shall be done in such a way as not to cause under-thrust on any part of the structure. Where suitable excavated material is to be used for backfilling, it shall be brought from the place where it was temporarily deposited and shall be used in backfilling. The scope of work for backfilling/ filling in
foundation, plinth, under floors etc. shall include filling for all the
buildings covered under the
contract. Surplus earth available from one building, if required, shall be used for backfilling /filling for other buildings also within
the
specified lead
mentioned in the item.
All timber shoring and form work left
in the
trenches, pits, floors etc. shall be removed after their
necessity ceases and trash of any sort shall be cleared out from the excavation. All the space between foundation
masonry or concrete and the sides of excavation shall be backfilled to the
original surface
with
approved materials in
layers
not
exceeding 150mm,
in thickness, watered and well consolidated by means of rammers
to at least 90% of the consolidation. Areas inaccessible to mechanical equipment such as areas adjacent to walls and columns etc. shall be
tamped by hand rammer or by hand held power rammers to the required density. The
backfill shall be uniform in character and free from large lumps, stones. shingle or boulder not larger than
75mm. in any direction, salt, clods, organic or other foreign materials which might rot. The backfilling in plinth
and
under floor shall be well consolidated by means of mechanical or hand operated rammers
as specified to achieve the required density.
Test to establish proper consolidation as required will be carried out by the Department at rates specified. Two tests per 50 sqm. will be taken to ascertain the proper consolidation.
The cost of tests carried out will be recovered from the contractor’s bill.
FILLING IN PLINTH AND UNDER
FLOOR
After the
available
suitable
excavated
materials are
exhausted
as backfilling, the contractor shall
notify the Engineer-in-charge of the fact and levels taken jointly with Engineer-
in-charge. The earth, murrum,
sand, gravel etc. or such materials suitable for filling proposed to be filled under floors and so mentioned in t
he
item of schedule of quantities shall then be brought to site from approved locations and sources.
EARTH FILLING
The earth, soft murrum etc. so brought shall be filled up in layers of 15 cm depth, each layer being well watered and consolidated by approved hand or
mechanical
tampers
or other suitable means to achieve the required density.
GRAVEL OR SAND FILLING
Gravel if required
to be
filled
under floors,
shall be
single washed gravel of approved
quality
and of size
varying from 12mm t0 20mm. it shall be uniformly
blind with approved type of soil and / or sand to obtain full
compaction. Gravel shall be filled in specified thickness and shall be well watered and rammed entirely
to
the satisfaction of the Engineer-in-charge.
If sand
is
required to be filled
under floors,
it
shall be clean, medium grained and
free
from impurities. The
filled in sand shall be kept
flooded with water for
24hrs. to
ensure maximum consolidation shall be done by the contractor at his own cost. The surface shall then be well dressed and got approved from Engineer-in-charge before any
other work is taken over the fill.
LEAD AND LIFT
Lead: The lead for disposal / deposition of excavated materials shall be as specified in the respective item of work. For the purpose of measurements of lead,
the
area to be excavated
or filled or area on which
excavated material is to be deposited/ disposed off shall be divided in suitable blocks and for each of the block, the distance between center lines shall be taken as the leads which shall be measured by the shortest straight line route on the plan and
not
the actual route adopted.
Lift: Lift shall be measured from
ground level. Excavation up to 1.5m depth below ground level and depositing
excavated material on the ground shall be included in the item
of
earthwork for various kinds of soil. Extra lift shall
be
measured in unit of 1.5m or part thereof. Obvious lift shall only be measured that is lifts inherent in the lead due to
ground slope shall not be
measured, except for lead up to 250m. All excavation
shall be measured in
successive stages of 1.5m stating
the commencing level. This shall not apply
to
cases where no lift is involved as in hill side cutting.
MODE OF MEASURTEMNTS
All excavation in areas having depth more than 30cm. pits,
trenches etc. shall be measured
net. The dimensions for the purpose of payment shall be reckoned on the horizontal area of the excavations for the purpose of payment shall be reckoned on the horizontal area of the excavation
at the base for foundations of the walls, columns, footings,
rafts
or
other foundations,
multiplied by the
mean depth from the surface
of
ground
determined by levels. Excavation for side slopes will not be paid for. Excavation in areas having depths less than 30 cms. shall be measured as surface excavation on square meter basis, mentioning the average depth of
excavation.
Reasonable working space beyond concrete dimension required for waterproofing
and shuttering where considered necessary
in the opinion of Engineer-in-charge will be allowed in execution and considered for payment for underground water tank,
sump septic tank
etc.
Where direct measurements of rock excavation are not possible, volume of rock can be
calculated on the basis
of length, breadth,
and depth of stacks made at
site as mentioned
in para 1.5.1 (c).
The
net volume shall be worked out by reducing it by 40% taking the voids into consideration as 40%. Similarly to arrive at net quantity
to be paid in
the
case of soil,
reduction at 20% of corresponding stack / truck measurements shall be made.
The rate for excavation shall include carting and disposing and leveling the excavated materials within the specified lead. The rate shall also be inclusive of cost of all tools, plants, explosives, shoring, dewatering at various stages, labour, materials etc. to
complete all the operations specified.
The backfilling and consolidation in sides of foundation and in plinth with
excavated material will not be paid
for
separately. The rate quoted
for
excavation shall be deemed
to have been
included
the cost of stacking of excavated materials, conveying within the specified lead, picking of selected stacked materials, conveying it to
the
place of final backfill,
compaction to the required
proctor density etc.
Payment for filling
and consolidation inside the trenches, sides of foundations, plinth etc. with selected
materials brought by the contractor other than the excavated material, shall be paid for separately
as per the rates
in schedule of quantities which includes cost of such materials/ excavation,
royalty,
its conveyance within the
specified lead, watering, consolidating, dressing etc. Actual quantity of consolidated filling shall be measured and paid in
cubic meters up to two
places of decimal.
The rate quoted in cum. for items of excavation is deemed to include the necessary additional quantity of excavation involved beyond the plan dimensions of the work which may
be necessary to be carried out for carrying out the work
in an engineering made, decided upon
by the
contractor.
Therefore
no extra payment will be made for any excavation done other than the required quantity as per the plan dimension indicated in the
drawings.
Measurements for excavation over areas shall be determined by levels or by "Dead men" or both at the discretion of the Engineer-in-charge. If however the Engineer-in-charge decided on measurement by levels,
levels of site shall be jointly taken and recorded by the Engineer-in-
charge or his representatives and the contractor, before commencement of the work and after completion of the work and the quantity of work
done shall be computed based on these levels. The volume of earth work
shall be computed based on "Simpson's
formula
' or any other approved method at the discretion
of the Engineer-in-charge.
