Pavement Quality Concrete

7/27/2019 Pavement Quality Concrete

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Construction of Pavement Quality Concrete

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TABLE OF CONTENTS

Clause No Description Pages

1.0 PURPOSE 2

2.0 SCOPE 2

3.0 DEFINITION 2

4.0 REFERENCE 2

5.0 CONSTRUCTION METHODOLOGY 3-85.1 Manpower deployed 3

5.2 Equipment deployed 3

5.3 Materials for PQC 3-4

5.4 Proportions of material &mix design 4

5.5 Site trials 4

5.6 Construction methodology 5

5.6.1 Clearing and under laying surface 5

5.6.2 Placing of separation membrane 5

5.6.3 Joints 5

5.6.3.1 Transverse contraction joint 5

5.6.3.2 Transverse expansion joint 5

5.6.3.3 Longitudinal joint 6

5.6.4 Batching and mixing 6

5.6.5 Laying and compaction 6

5.6.6 Texturing 7

5.6.7 Curing 7

5.6.8 Joint cutting 7

5.6.9 Sealing the joints 7

5.6.10 Weather and seasonal limitations 8

5.6.11 Tolerance of material 8

5.6.12 Quality control of works 8

6.0 TESTING AND ACCEPTANCE PROCEDURES 8

7.0 OCCUPATIONAL HEALTH & SAFETY MANAGEMENT PLAN 8


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1.0 PURPOSE:

This submittal pertains to methodology adopted by H.C.C. for Laying of PavementQuality Concrete. This statement describes the construction methodology andcovers production patterns, personnel involved, equipments used, testingfrequencies and quality control methods planned to be executed for this work. Thestatement subject to the clients approval will be used as a guide by the field staff,engineers etc. for the construction of the pavement quality concrete layer to thesatisfaction of the Engineer.

2.0 SCOPE:

The scope of this methodology covers following activities:

Survey and setting out works

Identification of sources, selection of materials of PQC and other materials &storage, handling & testing of all materials

Laying of pavement quality concrete

Recording of all results / inspection data etc. in relevant inspection and testformats and controlling of all inspection / test records / files as per existinginternal document control system for identification and traceability.

3.0 DEFINITION:

Definitions of various terms used in this methodology will have the same meaningas described in the DEFINITIONS as given below.MoRTH: Ministry of Road Transport & Highways specificationIS: Indian standardsPQC: Pavement Quality concreteDLC: Dry Lean concrete

4.0 REFERENCE:

MoRTH: Ministry of Road Transport & Highways specification (Fourth revision)

Additional Technical Specification


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5.0 CONSTRUCTION METHODOLOGY:

5.1 Manpower Deployed:Section in charge will be responsible for execution and Quality Control Managerwill be responsible for quality of all works for laying of pavement quality concrete.Both will liaise with Engineer. Further, surveyors and supervisors will assist fieldengineer whereas lab technicians will assist quality control engineer.

5.2 Equipment Deployed:Following Equipments will be deployed for laying of pavement quality concrete.

Batching plant of capacity 30cum/hr with automatic controls, for makingconcrete.

Transit mixer of required capacity to carry the concrete from batching plant towork spot.

Screed, to spread the concrete to required dimensions and initial compaction ofconcrete.

Needle vibrators for compaction of concrete.

Joint cutting machine, to provide the joints to required dimensions in concrete.The saw machine having sufficient no. of diamond-edge saw blades andmachine shall be either electric or diesel driven type.

5.3 Materials For Pavement Quality Concrete:

Crushed coarse aggregate:Coarse aggregate from approved source, Pali stone Quarry confirming to IS: 383shall be used.

Fine Aggregate (Sand):

Sand from Approved sources confirming to IS: 383 will be used.

Cement Source:ApprovedOPC 53 grade cement, stocked at Batching plant.

Admixture:From Fosroc, BASF, SIKA , conforming to IS: 6925 and IS: 9103.

Concrete:

Batched and mixed at the batching plant. Lead-time to stretch will vary along the

stretch; maximum time to reach extreme points being 30 40 minutes.


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Water:Water for mixing and curing of concrete shall be clean and free from oil, salt, acid,vegetable matter or other substances harmful to concrete. Water shall conform torelevant specifications stipulated in IS: 456. Water from approved Bore well near

batching plant will be used.

Mild steel bars for dowels and tie bars:These shall conform to the requirements of IS: 432, IS: 1139 and IS: 1786 asrelevant. The dowel bars shall conform to grade S240 and tie bars to grade S415of IS.

Pre-moulded joint filler:Joint filler board for expansion joints is of firm compressible material and complyingwith the requirements of IS: 1838.

Joint Sealing Compound:Polysulphide type sealant from Approved sources conforming to BS: 5212: 1990shall be used.

Separation Membrane:Separation membrane shall be impermeable plastic sheeting 125 microns thick.

5.4 Proportion of materials and mix design:The minimum cement content in PQC is 350kg/M3 and Maximum cement contentis 425kg/M3 of concrete. The compressive strength of 28 days will not be less than45Mpa & Flexural strength not less than 4.7Mpa as per contract specification. Theproportioning of material and the design mix shall be carried our as per IS: 10262and SP: 23 & to be submitted for Engineers approval.

5.5 Site Trials:The trial paving will be carried out on the road alignment under the supervision ofthe Engineer. The trial will be carried out to demonstrate the suitability of plant,equipments and work procedures to provide and compact the concrete to thespecified proportions, density, void contents and to confirm that, any otherspecified requirements as per contract specification be achieved. Trial will becarried out over two days with a minimum of 30-meter stretch each day and all

longitudinal and transverse joints will be constructed as per the approved drawing.Tests on trial will be carried out as specified vide clause 602.10.5 of MoRTH


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specification. Three numbers of core from each trial stretch will be taken not before7 days to determine the density of the concrete, thickness, air voids and to checksegregation by visual inspection. The temperature development in the concreteslab during hardening will be recorded. All data retrieved from the trial stretchesi.e; In-situ density, air void, pavement thickness, texture depth, surface regularity,alignment of dowel bars etc will be submitted separately.

5.6 Construction Methodology:

5.6.1 Cleaning The Underlying SurfaceAfter marking to the required widths and lengths on DLC surface, cleaning of DLCsurface shall be done with manual brooming and / or compressed air.

5.6.2 Placing Of Separation MembraneA separation membrane of 125-micron thick white in colour, transparent &impermeable in nature shall be placed between the DLC and PQC layer. Beforeplacing the membrane DLC layer shall be swept clean of all extraneous material.Where overlap is required it shall be of 300mm minimum. The membrane shall benailed to the DLC with nails and no standing water on or under the membrane shallbe allowed before placing concrete.

5.6.3 JointsBoth transverse and longitudinal joints have been discussed here. All the jointsshall be made in accordance with approved drawing. Transverse joints are furtherclassified as contraction joints, expansion joints and construction joints.

5.6.3.1 Transverse Contraction JointContraction joints shall be provided at 4.5m c/c in the longitudinal direction exceptat expansion joint locations. 32mm dia MS dowel bars of length 500 mm shall beplaced at 150 mm from the top of the separation membrane layer, spacingbetween bars will be 180mm c/c. Dowel bar shall be supported on a cradle in apre-fabricated joint assembly that will be positioned prior to the laying of the PQClayer. The cradle consists of 8mm MS bar bent in the shape of a U and supportedby 8mm MS rods. Dowel bar shall be painted with corrosive paint and covered by athin plastic sheath for a minimum length of 300mm from one end. A groove of11mm thickness and 110mm depth runs all along the transverse direction justabove the center of the dowel bar arrangement.

5.6.3.2 Transverse Expansion joint

Expansion joints are consisting of joint filler board and 32mm plain MS bars of

length 500 mm covered by a thin plastic sheath for a minimum of 275 mm length ofthe bar placed at 150 mm from the top of the separation membrane. The bars are


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placed at 180mm c/c and the expansion joint is spaced at 30mtr c/c in thelongitudinal direction or at end of the days work. On the other end of the dowel bar,a 300mm long closely fitted PVC cap filled with sponge for a length 30mm will beprovided. A similar cradle arrangement as above for supporting the dowel bar isfollowed.To separate the slabs adjacent to the expansion joint completely, a joint filler boardof thickness 20mm is positioned vertically along the line of the joint. A groove ofthickness 20mm and 25mm deep is made all along the centerline of the expansionjoint while the concrete is still green.Space around the dowel bar, between the lower concrete layer and the filler board

is packed with a suitable compressible material to block the flow of cement slurry.5.6.3.3 Longitudinal joint

The longitudinal joints shall be saw cut as per details in approved drawing. Tie barswill be used in longitudinal joints. These are of HYSD with minimum strength415Mpa or Fe500 TMT. 12mm dia 640mm long will be provided at a spacing of 560mm c/c, A start end and stop end is fixed at the position where concrete is to beginfor the day and is expected to close for the day. At the stop end position, thedowels of 25mm are capped along with sponge inserted so as to facilitate the easymovement of the dowel while expansion of concrete. The groove shall be cut afterfinal set of concrete.

5.6.4 Batching and MixingBatching and mixing of the concrete shall be done at batching and mixing plant.Proportioning of materials shall be done in the batching plant by weight as perapproved mix design.

5.6.5 Laying and CompactionIn case of screed operations for outer lanes of 3.5m, the side shutters are fixedalong the lane that is to be concreted, taking lines and levels from the surveyor.The gaps between the bottoms of side shutters shall be plugged with wedges/foam sheets to prevent escape of slurry. In case of inner lanes of 3.5m, the existingouter lanes serve the purpose of side shutters. In both cases a pair of masonsbehind the screed take care of any irregularities etc.

The concrete from batching plant shall be transported in transit mixers to the workspot. Concrete shall be dumped to position in front of screed. The screed moves ata speed of approximately 0.2 m/min in an even manner without segregation, sothat after compaction the layer will be of specified thickness of 300mm. Before thepaving starts for a particular stretch, form / shutter panels are fixed with marking onthem to specify the depth of concrete at that end of the stretch. The screed is to beset to lay the PQC layer of width 3.5m. The lead of the tipper from the batchingplant to the paving site is so timed that the entire operation of spreading,

compacting and finishing the concrete from a particular tipper is completed within


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90 minutes when the concrete temperature is between 25 and 30 degrees Celsius.The slumps required at site will be kept between 50 and 75.

Compaction shall be carried out immediately after the material is laid and leveled.The concrete is given a rough level of paveable thickness & the screed is passedto give further surface vibrations and achieve the accurate finish level. Initialcompaction during laying of concrete will be achieved by the tamping bars of thescreed. In order to ensure thorough compaction, needle vibrators will be used onthe full width of the lane till there is no further visible movement.

5.6.6 TexturingWire brush or other suitable means of appropriate size as described in MoRTHClause: 602.9.8.2, shall be used for texturing the surface evenly across the slab intransverse direction, immediately after the finishing of the concrete surface andbefore the application of curing compound. A labour on the working platform shallbrush the surface. The texture depth will be measured by sand patch test asdescribed in clause 602.12 of MoRTH. An average of 5 measurements will be

taken for each day of paving between 24 hours and 7 days after the construction ofthe slab.

5.6.7 CuringImmediately after surface texturing, the surface and sides of the slab shall be curedby the application of approved curing compound with the help of a manual sprayer.Curing compound shall be stable and impervious to evaporation of water from thesurface of the concrete within 60 minutes of application. The compound shall notreact with the underlying concrete layer or the film will not crack, peel ordisintegrate and have a water retention efficiency index of 90%.In addition tospraying of the curing compound, the fresh concrete surface will be protected fromadverse atmospheric conditions by warping with polythene tents for a minimumperiod of 3 hours, and then it will be covered with moist hessian cloth till completionof curing.

5.6.8 Joint cuttingOn well-cured concrete, after a gap of 6 hours from the start of concreting thetransverse joints namely contraction and expansion joints shall be cut as perapproved drawings. Contraction joints shall be 11mm wide and 110mm deep. TheExpansion joints are cut initially in a fashion similar to the contraction jointswhereas they are widened as 20mm wide and 25mm deep. Curing with thick

hessian cloth will be done immediately after the joints are cut. These will be keptcontinuously moist by sprinkling water as per specification.


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5.6.9 Sealing the jointsAfter the grooves are widened to the required widths and depths, joints will besealed with polysulphide sealants. A preliminary preparation of the groove in theway of cleaning off the dirt, by air compressor or in some cases by pressurisedwater jets. The groove will then be dried. To break the bond between the bottom ofthe groove and the sealant, a highly compressible and heat resistant paper backeddepending strip of width greater than the width of the groove is inserted so that thesealant does not leak through the cracks in concrete.

5.6.10 Weather & Seasonal limitationsDuring monsoon required number of tarpaulin and shall be provided along the lineof work. In case of rains during concreting using tarpaulin sheets shall adequatelyprotect all the freshly laid concrete, which had not been covered for. Any concretedamaged by rain during laying shall be removed and replaced. If the damages are

limited to textures only, it shall be re textured in consultation with the Engineer.In hot whether precautionary measure shall be taken to maintain the temperatureof concrete below 300C at the paving site.

5.6.11 Tolerances for materials

Joint filler board used in transverse expansion joint to be within +/- 1.5mm.

For paving works, the slump value in the range of 50 to 75 mm is reasonable.

For bars supported on cradles:

All bars to be within (+/-3) mm per 300mm length.

2/3rd of the bar to be within (+/-2) mm per 300mm length.

No steel bar of the cradle assembly shall be continuous across the joint.

5.6.12 Quality control of worksSurface levels: +5/-6mmSurface regularity of pavement courses: as per table 900-2 of MOST Cl. 902.4

Rectification of regularity of the surface: The defective length of the courseshall be removed to the full depth and replaced with conforming material. The areashall be at least 3m long, not less than 1 lane width and will extend to the fulldepth. Before laying this course, the disturbed sub base layer is corrected byleveling, watering and compacting.

6.0 TESTING AND ACCEPTANCE PROCEDURES:


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All the Inspection and Test requirements will be carried out as per TechnicalSpecifications and other Codes/Standards as mentioned in References Chapter.All the Records shall be properly controlled and maintained in easily identifiableand traceable manner.

Any Non-Conformity observed during Field Inspection and also during Testing ofMaterials the same Non-Conformity shall be recorded in the specified Format andnecessary Corrective/Preventive actions shall be initiated to prevent such things infuture. All Product Non-Conformities shall be observed, recorded,corrective/preventive actions and closing of NCRs shall be as per the procedure.

7.0 OCCUPATIONAL HEALTH & SAFETY MANAGEMENT PLAN:The OH & Safety Management Plan for the Project has been prepared to meet thevarious Safety requirements as mentioned in Contract Documents and also as perthe established OH & Safety Management Systems and Procedures of HCC.