TECHNICAL INSTRUCTION NO 10/2011 SPECIFICATIONS FOR CONCRETE AIRFIELD ...

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TECHNICAL INSTRUCTION NO 10/2011
SPECIFICATIONS FOR CONCRETE AIRFIELD PAVEMENTS
SECTION-1: MATERIALS
1. Introduction.
1.1 TI 10/87 was introduced in 1987. The construction technology, plant and
machinery have gone through a revolution phase in last 23 years. IS codes and IRC
codes have also been amended. The ICAO manual on which the designs of pavement
are based has also been amended. Although necessary amendments and policy letters
have been issued from time to time, the amendments in the TI had become essential.
This TI covers the materials and construction techniques involved in providing concrete
pavements for runway, taxi tracks, aprons, hard standings, operational readiness
platforms and floors for hangars/aircraft shelters. This TI does not include the structural
design aspects of pavements, which depends on the local factors and condition of the
sub-grade. The specification and techniques are to be followed strictly to improve quality
of work.

2. Materials.
2.1 Cement: Cement used in the work should conform to one of the following
standards:-
(a) IS: 8112 - Ordinary Portland Cement 43 Grade.
(b) IS: 12269 - Specification for High Strength Ordinary Portland Cement
53 Grade.
(c) IS: 12330 Sulphate Resisting Portland Cement. (If soluble salt like sulphate
in soil is more than 0.5 per cent)
(d) IS: 1489 Pt-I Portland Pozzolona Cement(Fly ash content not more than
25 per cent by weight of OPC)
(e) Portland Pozzolona cement, IS:1489 (Flyash content not more than 25 per
cent by weight of PC)
2.2 In case different type of cement is to be used, prior approval from Design Sub
Dte, E-in-C’s Branch should be obtained after the design mix is finalized and record
should be kept showing type of cement to be used for each slab. Two types of cement
should never be mixed together or used in any one slab. Proper storage facilities to
prevent deterioration of cement during storage due to climatic and other causes should
be provided. Cement remaining in stores for more than three months from the date of
manufacture must be retested before use and to be rejected, if it fails to conform to any
of the requirements of the specifications. High strength cement shall be used for Rigid
Overlays. Its 7 days compressible strength shall not be less than 330 Kg/ sq-cm i.e. it
should conform to IS: 8112 (latest revision). However it is desirable to use HSC with 7
days compressive strength not less than 370 Kg/ sq-cm.
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2.3 Fly Ash. Fly ash as per specification given in IS: 3812(latest revision) may be
used as admixture. Decision to use fly ash should be taken at planning stage after
identifying the source and carrying out necessary tests. Design mix using fly ash as per
IS: 456(latest revision) should be approved by competent authority and recommendation
for compaction and curing should be obtained from the agency preparing design mix.
Extensive trials should be conducted at trial bay/length stage before incorporating fly ash
as admixture to concrete.
2.4 Water.
2.4.1 Water for mixing concrete will ordinarily be obtained from a source which is used
for drinking. Where water from such a source is not available, it will be ensured that it is
clean and free from injurious quantities of acid, alcohol, salts, oil, organic matter or other
impurities. Sample of water should be sent to laboratory for testing. The provisions laid
down in clause 5.4 of IS: 456 (latest revision)be adhered to.
2.4.2 Arrangement should be made for the storage of water to ensure adequate supply
at all times during execution of the work so that concreting and curing operations are not
interrupted. Water stored for concreting should not be used for any other purpose.
Storage tank should be cleaned on regular basis every fortnightly and sample should be
tested in Govt approved Lab on quarterly basis.
2.5 Aggregates. Aggregates shall be natural materials conforming to
IS: 383(latest revision) but with Loss Angels Abrasion value not more than 35 per cent.
Aggregates shall be non-Porous, Hard, Strong, Durable, Clean and free from various
impurities and adherent coating and shall not contain any deleterious materials
exceeding the limits specified in the above IS and tested as per IS: 2386(latest revision).
Grading of aggregate will be as shown in Appendix ‘F’.
2.5.1 Coarse Aggregates. Where coarse aggregates of a maximum size more
than 20 mm are used, a separate bin shall be usede.gone bin to contain 20 mm
maximum aggregates size and the other to contain aggregates of the higher maximum
size. The proportion in which they are to be mixed to contain the desired grading has to
be worked out in the field. Coarse aggregate should be obtained from integrated cone
crushing plant having appropriate primary crusher, secondary crusher and vibratory
screen. It is desirable that for wearing course, aggregates obtained from igneous rocks
only be used.
2.5.2 Fine Aggregates. It shall consist of river sand, pit sand or crushed stone sand.
Tests for slit, clay and loam shall be carried out as per Appendix ‘A’.
2.6 Grading and Handling of Aggregates.
2.6.1 Grading of Aggregates. Grading of coarse and fine aggregates shall be as per
IS: 383(latest revision). Coarse aggregates and fine aggregates shall be mixed in
suitable proportions to get the final mix, which shall be within the specified limits. A sieve
analysis test of the mixed aggregates will be carried out at-least once a day at random
and result recorded.
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2.6.2 Handling of Aggregates. Stock piles shall be made immediately on receipt of
aggregates. Aggregates from different sources and different grading shall not be stacked
together. Separate size of coarse aggregates shall be stacked separately. In case the
concrete is to be mixed in a central batch plant, site of such plant will be decided keeping
in mind the interruptions to air and road traffic due to movement of tippers and the length
of the circuit route. In that case all materials shall be stockpiled around mixing plant.
2.6.2.1 Aggregates shall be staked on a hard surface so as to exclude the
possibility of soil or grass getting mixed. When stacked in close proximity, the stock piles
shall be separated by bulk heads to prevent the aggregates mixing together. Special
care will be taken to clean and wash the last layer of aggregates in contact with ground
surface before use.
2.6.2.2 Before batching, the aggregates shall have been stockpiled for at least 48
hours to allow for draining of water, if wet. Adequate provision should be made for stock-
piling aggregates to an extent sufficient to meet the needs of the work taking into
account the availability of supplies and rate of delivery. Aggregate should be covered
suitably after sample is taken for moisture content test to prevent ingress/escape of
moisture.
2.7 Load Transfer Device. Dowel bars and tie bars are not being provided since
single slab design is being followed. However same will be provided if specified in
design.
2.8 Pre-molded Joint Filler. The joint filler shall be pre-moulded, compressive filler
board, with high performance closed-cell material available in board form (HD 100)and
shall comply with the requirements of ASTM –D3575 /IS Standards(latest revision), Pre-
moulded joint filler shall be of the thickness as stated within a tolerance of ± 1.5 mm. It
shall providedfor the full width of slab between form-work.
2.9 Joint Sealing Compound. Poly-urethane/poly-sulphide cold joint sealant to
be used conforming to BS 5212 (Part 2)/IRC SP-57 2010 having movement
accommodation factor ±30%, flexible, resistance to age hardening, fuel resistance, heat
resistance and durable with 10 years warranty. The hot applied sealing compound shall
comply with the requirements of IS: 1834(latest revision). Fuel and heat resisting joint
sealing compound complying with grade ‘B’ of the IS Code should be used. Before filling
the sealant, polyethylene backup rod of suitable size shall be placed mechanically.
Masking tape should be fixed on the sides to avoid spillage.
2.10 Polyethylene Back Up Rod. Alkali resistant and non staining polytheneBack
Up Rod shall be used in the joints. The diameter of rod should be ¼ times more than the
joint width. It should be placed mechanically so that the depth is uniform. The bar should
conform to ASTM C 1016-1994A, ASTM D 3575-1993 and ASTM D 5249-1992. Before
placing the backup rod it should be free from moisture, dampness, oil stains paint and
any type of loose aggregate.

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2.11 Synthetic Fibre. Non circular synthetic fibre of length 12 mm, specific gravity
1.31 to 1.41, UV stable and alkali resistant ( as per ASTM C 1116-02 and ICAO AC 32)
to be used up to 0.25% by wt of cement as per manufacturers specification, if specified
in the design. Design mix to be prepared after incorporating fibres.
2.12 Curing Compound. Curing compounds shall contain sufficient flake
aluminium in finely divided dispersion to produce the complete coverage of the sprayed
surface with a metallic finish. The compound should become stable and impervious to
evaporation of water from surface of the concrete within 60 min of application and shall
be of approved type. The curing compound should have a water retention efficiency
index of 90% in accordance with BS specification No 7542 and conformation with ASTM
c 309-74. The curing compound shall not react with the concrete and the film or
membrane shall not crack, peel or disintegrate within three weeks after application.
Immediately prior to application, the curing compound shall be stirred thoroughly in its
containers. The rate of spread should be as per manufacturer’s instructions (approx. 3-5
m2 / litr depending on the concrete surface)and shall be checked during the construction of
trial length and subsequently whenever required by the engineer. Mechanical sprayer
should be used for continuous agitation and mixing of compound during spraying.

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SECTION-2: CONCRETE MIX DESIGN AND PLACING OF CONCRETE
3.0 Mix Proportions.
3.1 Mix Design. A mix will be designed based on flexural strength as given in design
after taking into account the type of aggregates, plant and method of laying to give the
desired workability, which will enable the concrete to be properly compacted to its full
depth and finished to the surface tolerance specified. Details of concrete mix design, for
rigid pavements are given in TI 12/87 and should be as per SP 23. Design mix shall be
different for different type of cement and for use of admixtures in hot climate.
3.2 Water/Cement Ratio. The term water /cement ratio means the ratio by
weight of water to cement in the mix expressed in decimal terms. The water to be taken
into account for this purpose is that which is free to combine with the cement in the mix,
including free water in the aggregates. This is over and above the water, which may be
absorbed by the aggregates. The actual quantity of water to be added in the mix at any
time will depend on the water cement ratio adopted as well as the difference between the
actual and the saturation moisture content of the aggregates used. Site document shall
be maintained for use of different w/c ratio on daily basis.
3.3 Cement Content. The minimum cement content for the mix corresponding to
4.5 MPa flexural strength in the field at 28 days is given as under:-
(a) When Ordinary Portland Cement (OPC) is used the quantity of OPC shall
not be less than 400Kg/cum. In case fly ash (as per IS:3812-Part I) is blended at
site, the quantity of fly ash shall be up to 20 per cent by total weight of
cementitious materials and thequantity of OPC in such a blend shall not be less than 360
kg/cum. If this minimum OPC content is not sufficient to produce concrete of the
specified strength, it shall be increased as necessary by the Contractor at his own
cost. The OPC content shall, not exceed 425 Kg/cum of concrete.
(b) In the case of factory produced PPC, (with fly ash content restricted to 25
per cent), the total quantity of cementitious material (OPC+ fly ash) shall not be
less than 425 kg/cum. In case the specified strengths are not achieved, the
quantity of PPC shall be increased as necessary by the Contractor at his own
cost.
3.4 Trial Mix. Trail mixes should be made and beams tested for their flexural
strength. For each trial mix, nine preliminary test beams should be made and tested in
accordance with IS: 516. For compaction in the moulds of beams, Appendix ‘B’ will be
followed. Three of these beams shall be tested for seven days and three 28 days flexural
strength. If the differences between the highest and lowest values at 28 days strength
from any trial mix is more than 15% of the average strength of three beams, the test is to
be discarded and a further trial mixes shall be prepared. The mix giving the design
flexural strength will be approved. Nine preliminary test cubes will also be made of the
same approved mix used for casting beam. Three cubes will be tested to find the
corresponding crushing strength of the concrete at seven days and three others at 28
days. The remaining three beams and three cubes, if the mix is finally approved, will be
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preserved carefully for one year from the completion of work for test or any subsequent
check. Crushing strength of concrete arrived at thereafter be specified for testing and
acceptance of concrete in field. For testing and acceptance of quality concrete for airfield
pavements, refer TI 16/87.
4.0 Preparation of Base.
4.1 Before fixing the form works for laying concrete, the base shall be checked for
proper compaction density and levels and record of the same shall be kept. Base shall
be laid using paver with sensor. Whenever specified, approved standard water proof,
wrinkle free craft/polyethylene sheeting (minimum 400 micron thick) without puncture
shall be laid to prevent absorption of water for the concrete mortar. Before placing the
membrane, the surface shall be cleaned of all the extraneous material using air
compressor. Where-ever overlap is required, minimumoverlap shall be 300mm. The
damaged/punctured sheet should be replaced. In case of overlays, the existing surface
shall be kept moist in saturated condition. Important aspects about sub-grade, sub-base
and base have been discussed at Appendix ‘G’ attached.
5.0 Trial Bays/Trial Lengths.
5.1 Trial Bays. Before commencement of the work, where paver cannot be used a
trial bay of 3.5X3.5 meter square, of the approved concrete mix shall be laid at suitable
place as soon as possible before the actual concrete pavement work is to start. The
method of mixing, spreading, curing and compacting shall be the same as laid down in
the specification for work. At-least three cores shall be cut when the concrete is seven
days old, in order to determine the degree of compaction achieved. Alternately the
concrete shall be broken and cut by pneumatic hammer or a pick-axe and a saw. Should
any of cores or the cut portion show honey-combing in the concreting, a further trial bay
shall be laid after improving the techniques of spreading and compaction and shall be
tested as before. Needle vibrator, screed type of vibrator and paver to compact the
pavement concrete shall be used as planned for the actual execution. On no account
should the cut portion of the sample concrete exhibit honey–combing. When the water
cement ratio for the mix has been worked out for achieving the definite strength, it will
result in reduced aggregate/ cement ratios and reduce the unit yield of the concrete.
However extreme care shall be exercised not to exceed the specified Water Cement
Ratio. This will be done by forbidding use of under-graduated receptacles and preventing
spillage. The frequency of the vibrator plays an important role in the efficiency of
compaction and it shall be checked at frequent intervals. Further trial bays shall be laid
and degree of compaction tested as before until the method of spreading and
compaction has been so improved that the cores or cut portions do not show honey-
combing. The trial bays should also be given the described surface finish as described in
Para 10.
5.2 Trial Length. The trial length shall be constructed at least 14 days in
advance of the proposed date of commencement of work. At-least 30 days prior to the
construction of the trial length, the contractor shall submit for the Engineer’s approval a
detailed Method Statement giving description of the proposed material, plant, equipment
and construction methods. All the major equipment like paving train, batching plant,
tippers, etc., proposed in the construction are to be approved by the engineer before
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their procurement. The trial length should be constructed away from carriage way. The
Engineer-in-charge shall also approve the location and length of trial construction which
shall be a minimum of 60 m length and for full paver width of the paver. The trial length
shall contain the construction of at least one transverse construction joint involving
hardened concrete and freshly laid subbase. The construction of trial length will be
repeated till the contractor proves his ability to satisfactory construct the pavement in
subsequent trials. The hardened concrete shall be cut over 3 m width and reversed to
inspect the bottom surface for any segregation taking place. The length shall be
constructed after making necessary change in the gradation of the mix to eliminate
segregation of the mix. The lower surface shall not have honey-combing and the
aggregate shall not be held loosely at the edges.
6.0 Form Work.
6.1 Steel Forms.
6.1.1 All side forms shall be of mild steel except for curves having a radius of less than
45 meters, which may be of wood. The steel forms shall be of M.S. Channel section.
Depth of side form shall be equal to the thickness of the pavement.
6.1.2 A side form shall have a length of at-least 3 meters in case of longitudinal joints
except on curve of less than 45 meters radius where short length may be used. In case
of transverse joint, a full length of bulkhead shall act as form work. When set to grade
and stacked in place, no deviation of the top surface from the specified level shall be
allowed.
6.1.3 The method of connection between the two lengths of forms shall be such that the
joints formed are free from play or movement in any direction. Use of bent, twisted or
worn out forms shall not be permitted. At least three stake pickets for bracing pins or
stakes shall be provided for each 3 meters of the forms. The bracing and support must
be adequate to prevent springing of the forms under the pressure of the concrete or
weight or thrust of light machinery (like vibrator screed) operating on the forms. Separate
rails are to be provided with adequate fixing arrangements if mechanical paver is used
for laying the pavement slab. While removing the steel forms, care should be taken to
withdraw them gradually so that edges of the slabs are not damaged. In no case, the
form will be nailed to existing/adjacent concrete surface
6.2 Wooden Forms.
6.2.1 Wooden forms may be used only for curves having a radius of less than 45
meters. Wooden forms shall have smooth surface on inner side and shall have a
minimum base width of 10 cm thick for slabs upto 20 cm thick and a minimum base width
of 15cm for slabs over20 cm thick and their depth shall be equal to thickness of the
pavement at the corresponding edges.
6.2.2 Forms shall be held by stakes set at intervals not exceeding 2 meters and by
placing two stakes, at each joint. The forms shall be firmly nailed or secured to the side
stakes. And shall be securely braced as necessary to ensure that no movement results
from the pressure of the impact of the vibrator or temper during finishing of the surface.
The forms shall be caped along the inside upper edge with 5 cm angle iron. The edge
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shall be suitability recessed so that the outer face of the angle iron is flush with the upper
and inner face of the wooded forms. It is recommended to prepare angle iron and MS
steel form specific to curve rather than using wooden forms.
6.3 Setting of Forms.
6.3.1 Setting of forms shall be done according to the slab plan and concreting shall not
commence until the setting of the forms is approved.
6.3.2 Forms shall be set in advance to a length sufficient for at least one day’s
concretingand shall not be removed until at least 12 hours after the laying of the
concrete. Care must be taken in setting out the side forms to ensure that the bar width
shown in the drawing are strictly adhered to. The trueness of the formation shall be
checked by the means of 3m straight edge and precision level equipment and any
deviation greater than 1.5mm shall be rectified. No deviation from straight edge shall,
however, be permitted at the joints. Proper shuttering oil shall be applied to the form to
get good finish. For more details refer IS: 14687.
7.0 Batching and Mixing.
7.1 All the ingredients of concrete shall be batched by weight by combined batching
and mixing plants. Power driven mechanical concrete mixers of adequate capacity with
water measuring devices as per IS: 1791 and IS: 12119 in conjunction with weigh
batchers shall be used. Standby plant will be catered for to avoid disruption of the works.
7.2 A small quantity of water will be added before loading of aggregate and cement.
The remaining water shall be added during the mixing operation. The mixing will be done
for atleast two minutes and until a uniform colour and consistency is achieved. The
method of batching should be made fool proof. Batching of water by buckets, drums or
tins shall be strictly prohibited.
7.3 Quantity of concrete mixed in any one batch shall not exceed the rated capacity of
the mixer. The drum of the mixer should be completely emptied before ingredients for the
next mix are charged into it. Concrete mix as above shall not be modified by addition of
water or otherwise in order to facilitate handling or for any other purpose.
7.4 On cessation of work and during other stoppages exceeding 20 minutes, the
mixer and the other equipment/accessories used for handling wet mix shall be
thoroughly washed with clean water. Blades in the drum of the mixer which are worn
down 20 mm or more in depth shall be replaced with new blades.
8.0 Hauling&Placing and Compaction of Concrete.
8.1 Hauling/Transportation of concrete
8.1.1 Freshly mixed concrete from central batching plant shall be transported to the
paver site by means of tippers or transit mixers of sufficient capacities of approved
design in sufficient numbers to ensure a constant supply of concrete. Tarpaulin covers
shall be used for protection of concrete against weather. The tippers shall be capable of
maintaining mix concrete in a homogeneous state and discharging the same without
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segregation and loss of cement slurry. The feeding to the paver is to be regulated in
such a way that paving is done in an uninterrupted manner with uniform speed
throughout the day’s work.
8.2 Placing of Concrete.
8.2.1 Concrete shall be transported without delay and incorporated in the works before
initial setting time as per clause 13.2 of IS: 456- 2000 from the time of discharge from the
mixer unless special transportation devices are employed. Temperature of concrete must
be below 35⁰C. Concrete shall be placed and spread to such a depth that when
compacted and finished, it shall conform to the grade and cross section specified in the
plan to ensure the minimum slab thickness shown on the drawing to be obtained at all
points.
8.2.2 In order to obtain adequate compaction, the concrete shall be spread so as to
stand proud of the finished level and produce a surcharge of 20% of the required slab
thickness.
8.2.3 Concrete shall be placed in such a manner as to require as little handling as
possible. Spreading, compacting and finishing (except final boom/belt finishing)
operations shall be completed within a period not exceeding initial setting time from the
time the mixing starts. In case of dry and hot weather, this time will not exceed 35
minutes. Concrete shall be placed around manholes and other structures after these
have been brought to the correct alignment.
8.3 Compaction of Concrete.
8.3.1 Compaction shall be carried out by electrically operated needle and screed
vibrators as stipulated hereafter. Needle vibrators should be used all over the area for
obtaining initial compaction of the concrete. These should be of diameter not less than
4.5cm. If the vibrators are pneumatic, the pressure must not be below 4kg/cm2. If
electrically operated, they should have minimum frequency of 3500 impulses per minute.
Minimum number of petrol driven vibrators as specified by the Engineer-in-Charge with
minimum frequency of 3500 impulses per minutes shall be provided at each work site as
a standby arrangement. The vibrator shall conform to IS: 2505/1968, 2506/1968 and IS:
4656.
8.3.2 There should be at least three needle vibrators working in one day. Vibrating
screed consisting of a steel section or timber section of not less than 7 cm width and with
a vibrator mounted thereon shall follow needle vibrators to obtain full compaction. The
face of wooden tampering edge of the screed shall be lined with an M.S plate rigidly
fixed by means of counter sunk screws. Where screed vibrator are used for compaction,
a stand by unit shall always be maintained ready for use, should the other one go out of
order. Where electrically driven vibrators are employed, a standby pneumatic unit shall
be kept ready for use in case of power failures. Under no circumstances, honeycombing
of concrete at joints or elsewhere shall be permitted.
8.3.3 When using vibrating screed for compaction, it should not be dragged over the
concrete. During the initial passes, it shall be lifted to the adjacent forward position in
short steps. Subsequently, it shall be slowly slide over the surface with its axis slightly
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tilted away from the direction of sliding and the operation repeated until a close, dense
surface is obtained. Concreting shall be carried out in one operation between the
expansion joints and construction joints without any break at the dummy joints.
8.3.4 Use of slip form pavers with independent units designed to spread, consolidate,
screed, float finish and texture the freshly placed concrete in one complete pass of the
machine is mandatory for large works. Paver shall be equipped with electronic sensors
and controls to grade from either side of machine. Slip form/fixed form paver to be used
as per the guidelines given in MoRTH(Road Wing) Specifications clause no 602.9.5 and
602.9.6.

9.0 Finishing of Concrete.
9.1 Surface Finish.
9.1.1 Immediately after the compaction of concrete but before the concrete has
hardened (within 90 min of placing concrete) and while the concrete is still in a plastic
state, the pavement surface shall be inspected for irregularities with a profile checking
template and any needed correction made by adding or removing concrete by means of
long handled floats and scraping straight edge followed by further compaction and
finishing. The long-handled floats may be used to smoothen and fill in open-textured
areas in the pavement surface but the final finishing is to be made with scraping straight
edges.
9.1.2 The scraping straight edges are to be 3 meters long with flexible handles long
enough to reach the other side of slab when operated from inside of pavement. They are
to be placed parallel to the form at the side of the pavements and worked backwards and
forward uniformly across the width of the slab. After this operation has been completed
and the surface has been brought up to the required finish, the straight edges are to be
moved forward by not more than half their length and this process repeated. The straight
edge testing and re-floating is to continue until entire surface:-
(a) Is free from observable departure from the straight-edge.
(b) Conforms to the required levels and cross section.
(c) When the concrete has hardened, it shall conform to the specified surface
levels.

9.1.3 The foregoing work is to be carried out while the concrete is still plastic and
workable and in such time sequence as to ensure the removal of water of laitance from
the surface. After the concrete has sufficiently hardened to about 12 hours and not later
than 24 hours, the surface shall be tested again for high spots. All high spots shall be
marked and those exceeding 3 mm shall be ground down immediately. Care shall be
taken to ensure that the grinding does not in any way damage the concrete surface.

9.1.4 The final surface finish is to be such that when tested with 3 meters long straight
edge placed anywhere within the same or adjoining slab in any direction on the surface,
there is no gap greater than 3 mm between the bottom of the straight edge and the
surface of the pavement. This will not be required if slip form paver with guide wires is
used at appropriate paving speed and sensors.
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