PQC Laying

PQC laying at NH-
28…

BRIEF AND DETAILED SPECIFICATIONS OF PAVEMENT QUALITY CONCRETE (PQC)

PURPOSE:-  
        The purpose of this Quality Plan for Construction of Pavement Quality Concrete (PQC) is to provide detailed Construction Methodology, Materials used, Resources deployed.
SCOPE:-
        The Scope of this Segmental Quality Plan/ Methodology shall covers the construction of pavement quality concrete insertion of dowel bars, tie bars in accordance with the requirement of Technical Specifications and in conformity with the line, grades and cross sections shown in drawings.
It covers the following activities:
    Selection, Testing and Acceptance of all incorporated Materials for PQC.
   Design of Mixes for PQC and Trials, Acceptance etc.
   Details of Plant, Equipment / Machinery as required in execution of PQC.
   Batching, Mixing, Transporting, Placing, Finishing and Curing of Concrete for PQC.
   Mechanized Texturing and Curing operation for PQC.
   Joint Cutting and application of Joint Sealing compound as approved.
   Quality Assurance and Control Checks during operation and post concreting
DEFINITIONS:-
The words like contract, Contractors, Engineer (Synonymous to Engineer’s representative), Drawing, Employer, Government, Works, Worksite used in this Quality Plan shall be considered to have the meaning as understood from the definitions pertaining Quality Management System Developed for the Particular Project.
The following abbreviation shall have the meaning as set forth below:
   MORT & H: Ministry of Roads Transport & Highways
   NHAI: National Highways Authority of India
   BIS: Bureau of Indian standards
   QA: Quality Assurance
   PQC: Pavement Quality Concrete
   MTC: Manufacture’s Test Certificate
   ITP: Inspection Test Plan
CROSS REFERENCE:-
This Segment Quality Plan should be read in conjunction with the following documents:
   ISO 9001 2000 Quality management system
   Contractor Document / Technical Specifications
   MoRTH/IS/ASTM /ACI Codes, where applicable
   IRC: SP: 57-2000, Guideline on Quality system for roads.
  RESPONSIBILITY:-
S.
NO
Activity Description
Performing
Checking/
Verifying
Approving
01
Preparation Quality Plan
Section-in� charge &
QC Engineer
Works
Manager &
QC Manager 
Project
manager
02
Selection and Testing of various materials for PQC, Mix Design & Trials etc prior to start of activity
Section-in- charge & QC Engineer
Works Manager & QC Manager
Project manger
03
Survey, setting out fixing of string lines prior to start of PQC
Surveyor
Section-in-charge / Site Engineer
Engineer
04
PQC Paver deployment at various locations and other logistics management etc.
Section-in-charge / Site Engineer
Works Manager
Project
Manager
05
Batching & Mixing of concrete as per approved Design  mix
Batching Plant �in-charge
QC Engineer / Lab technician
06
Control of movement of Paver and maintenance 0checks / control during operation
Paver engineer      /  Supervisor
Paver- in � charge
Project Mechanical Engineer for effective control of Paving operation
07
Transportation,                   Placing, Compaction and finishing of PQC layers,
Section-in- charge  / Site Engineer
QC Engineer / Lab technician
Engineer
08
Texturing, curing  Joint Cutting and Sealing operations for PQC
Section-in-charge / Site Engineer
QC Engineer   / Lab technician
Engineer
09
Inspection & Testing of PQC as per approved ITP and maintaining all formats.
QC Engineer / Lab Technician
QC Manager / QC Engineer
Engineer
PROCEDURE:-
The detailed Construction Methodology involved in execution of PQC including Quality Assurance & Control etc. has been described in the following sub-chapters.
Survey and Setting out for PQC:
The following steps are involved in Setting out of string wire before lying
PQC:
   Center line of Carriageway will be marked at every 50M intervals on DLC surface by using Total station.
Approval of survey and setting will be ensured and survey check sheet CGGC 34 17 01 is filled prior to commencement of the laying activity.
Material Required:
Cement:
   Any of the following types of cement may be used with prior approval of the Engineer:
(i)                Ordinary Portland Cement                            IS: 269
(ii)             Portland Slag Cement                          IS: 455
(iii)           Portland Pozzolana Cement                IS:1489
Cement to be used may preferably be obtained in bulk form. It shall be stored in accordance with stipulations contained in Clause 1014 and shall be subjected to acceptance test prior to its immediate use.
.
Coarse Aggregate:
   Aggregates to be used in the construction of PQC will be Crushed aggregates .
   The aggregate complying IS: 383 will be used.
   Max  Size of coarse aggregate 25mm as per MoRTH  601.2.3.2 (Fourth Revision : August 2001).
Fine Aggregate:
   Clean, natural sand from River Banas form location Triveni 20km form Ladpura will be used. The material conforming IS: 383 is ensured.
   The fine aggregate shall consist of clean, natural sand or crushed stone sand or a combination of the two and shall conform to IS: 383. Fine aggregate shall be free from soft particles, clay, shale, loam, cemented particles, mica, organic and other foreign matter. The fine aggregate shall comply with MoRTH 602.2.4.3.(Fourth Revision : August 2001).
(The grading limits for all in aggregates shall be per IS:383 for 20mm nominal size Aggregate for Pavement Quality  Concrete )
                       
Sieve Designation
Percentage passing the Sieve by Weight
40 mm
100
20 mm
95 � 100
4.75 mm
30 � 50
600 micron
10 � 35
150 micron
0 � 6
Water:
   Water used for mixing and curing concrete conforming to IS:
     456: 2000.
   In case of PQC During hot weather, water for preparation of concrete will be taken form water chilling plant.
       Admixtures:
   Admixture conforming to IS: 6925 and IS: 9103 to improve workability of concrete or extension of setting time to be done.
      Storage of materials :
Aggregates:
   Aggregate will be stock piled separately and sufficient distance will be maintained from each fraction to avoid intermingling.
   Storage space must be easy to inspection, removal and restorage of materials.
   Regular testing of aggregate stock pile will be exercised to ensure required gradation control.
   
Cement
   Bulk cement will be stored in bulk storage containers having 200MT capacity and the number of such bulkers will be sufficient to cater to the requirement at site.
Water
   Water will be tanks covered at top and cleaned at regular intervals. The intake of pipe will be enclosed to exclude silt and other solid materials and there shall be a minimum depth of 0.60 m of water below the intake at all times.
    Proportioning of concrete
    
      Concrete Strength
   The pavement concrete should be a class M-40 concrete with a minimum 28 days compressive characteristic strength of 40 MPa
1.     Characteristic flexural strength at 28 days                = 4.5 MPa
2.     Target mean strength at 28 days                     = 5.80MPa          
3.     Water cement ratio                                          =0.45 Maximum
4.     Slump as per IS: 1199                                              =31+/-15 mm
   Minimum flexural characteristic strength of 4.5 MPa.
   The ration between the 7 & 28 days strengths of 4.5 Mpa.
   For each batch
                                                                        7days (avg.)
   The average flexural strengths ( R7)  =           
                                                                   28 days (avg.)
   R7 to be determined for three decimal levels.
(Flexural strength of any Six consecutive 7day test result)  >4.50+1.65*s
S: Standard deviation of the group.
         
Workability:
   The control of workability will be done by the slump test
   Slump will be controlled so that mix is compacted and finished without undue flow.
   The exact slump required at plant and site will be exercised during trail patch.
Separation Membrane :
   Two applications of approved wax-based white �pigmented curing compound will be applied on DLC.
   First coat will be applied immediately after DLC laying and compaction and the other before start of PQC.
   The process of application will be done using mechanical sprayer.
   The other parameters will be meeting the additional specification Clause- A-12.
Preparation of base :
   Any visible defects / cracks more than 10mm size to be required by fine cement concrete mix.
   Surface will be made clean of dirt or extraneous material and free from damage before application compound.
Joints:
   The exact location and type of joint to be transferred at site as mentioned in drawing.
    Concrete Penetrometer and testing as per ASTM C 403 will be used in monitoring setting of concrete / Maturity of concrete and saw cutting period.
   Initial saw cut of 3mm wide , 100mm depth in transverse and longitudinal direction will be provided after initial set(approximately 6~8hrs).
   Final saw cutting 10~12mm wide ,20~25mm depth will de provided after 14days of curing at accommodate joint sealant.
   The staggering of transverse joints with reference to the base will be minimum 0.3m.
         Transverse joints:
   Contraction joints will be provided at every 4.5m interval except where expansion joints are provided.
   Transverse joints to be provided at the junction of the approach slabs of bridged and the rigid pavement and special location e.g. transition sections i.e. transition of flexible vs. rigid pavement.
   Transverse joints will be straight within specified tolerances.
   Expansion joints will be provided at the junction of the approach slabs of Bridges and the rigid pavement.
          Contraction Joint:
   Contraction joints will be as per the drawing given by NHAI    
  Expansion Joints:
Joint filler board for Expansion joint will be premoulded joint filler as per MoRTH spec. 602.2.7
Premoulded joint filler conforming As per IS: 1838 or BS: 2630
   Thickness of the joint  = 20-25 mm
   Tolerance limit will be within +/-1.5mm
   It shall be 25 mm less in depth than the thickness of the slab
   The filler for each joint shall be furnished in a single piece for the full depth and width required for the joint.
   Holes to accommodate dowel bars will be as accurately board or punched to give a sliding till on the dowel bars.
   Dowel bars for expansion joint will as per
   Joints will be provided at the junctions of rigid and flexible pavement with transition slab as per the drawings.
   Where due to unavoidable conditions (for example:- joints at two contract package) joint are to be provided, dowel bars are fixed into the rigid pavement.
   The adjacent slabs shall be completely separated from each other by filling joint filler board.
Transverse construction joint
   Transverse construction joint shall be placed when concreting is done after a day’s work.
   It will be provided at the regular location of contraction joints using dowel bars.
   The joint will be made butt type.
          Longitudinal joints
   Tie bars shall be provided at the longitudinal joints as per the drawing given by NHAI.
Dowel bars
   These shall confirm to the requirements of IS: 432, IS: 1139 and IS: 1786 as relevant. The dowel bars shall confirm to Grade S 240 and tie bars to Grade S 415 of I.S.  
   It should be mild steel round, free from dirt, loose rust, scale straight and burring restricting slippage in the concrete.
   The dowel bars will be supported on cradles / dowel chairs in prefabricated joint.
   Dowel bars will be positioned at the mid depth of the slab with in a tolerance of + 20mm.
   Dowel bars shall be covered by a thin plastic sheath for at least 2/3 of length from one end for dowel bars in Contraction joint or half the length plus 50mm for expansion joints.
   The sheath shall se tough, durable and of an average thickness not less 1.25mm
   The dowel bars will be inserted by vibration method in the plastic concrete.
   For Expansion joints, a closely fitting cap 100mm long cotton waste placed over sheathened end of each dowel bar.
          Tie bars
    Free form oil, dirt, loose rust and scale.
   In longitudinal joints shall be deformed steel bars of strength 415 MPa complying with IS: 1786.
   It should protect from corrosion for 75mm on each side of the joint by applying bituminous paint.
   The coating shall be dry when the Tie Bars are used.
   It should be perpendicular to the line of the joint, with the center of each bar on the intended line of the joint within a tolerance of + 50mm and with a minimum cover of 30 mm below joint groove.
           Weather and Seasonal Limitations:
           Concreting during monsoon months:
   Sufficient supply of tarpaulin or other waterproof cloth will be provided along the line of work.
   Any concrete damaged by rain will be removed and replaced.
   If the damage is limited to texture it will be retextured.
          
  Concreting in Hot Weather:         
                   Care will be taken in reducing temperature of concrete such as use of
                   Chilled water, sprinkling of chilled water over aggregates.
         Guide wires
Use of guidewires
   Each guidewire shall be at a constant height above and parallel to the required edges of the slab as described in the contract / drawing within a vertical tolerance of + 3 mm.
   The guidewires shall be supported and stakes preferably not more then 8 m apart by connectors capable of fine horizontal and vertical adjustment.
   The stack shall be positioned and the connectors maintained at their correct height and alignment before commencement of work.
   The guidewire shall be erected and tensioned for at least 2 hours before concreting that section.
   Care will be taken to avoid any disturbance to the guidewire during paving by any construction equipment or any other means.
            CONSTRUCTION:-
10.1 Concrete production, transportation, Paving, Texturing and Curing:-
   A batching plant of 120cum per Hr. capacity has to use for Production of Concrete
   Dumpers having hydraulic jack system to unload having capacity 35 Mt (Approx. 9 cum) concrete will be deploy for transportation of concrete.
   Paving will be carried out in full carriageway width of 8.5 m length.
   The Paver used will be slip from Paver.
    The slip from-paving machine shall compact the concrete by internal vibration and shape it between the side forms with a conforming plate and oscillating finishing beams.
   The final finish of the surface will be done by super smoother attached to the rear portion of the Paver.
   Manson Trolley will be placed in between Paver and Texturing and Curing Mechine (TCM) for rectification of any surface defects.
   The alignment of the Paver shall be controlled automatically from the guide wire by 4 set of level sensors and 2 set of steering sensors attached to the Paver.
   Planning and preparation will be done to pave at least at an average uniform speed of one m / min.
   The surface of concrete slab will Tine-textured in a direction parallel to the longitudinal axis of the carriageway.
   Texturing / Tining will be done with a specified machine specially designed for the purpose for providing grooves at a uniform spacing of 18 mm to 21mm.
        Depth = 3mm to 4mm
        Width = 3mm
   Curing of PQC using curing compound will be followed by texturing by the same TCM.
   Curing will be taken care at the edges also.
   The curing compound will be resin based aluminized reflective curing compound.
   After providing initial cut entire PQC will be covered with Hessian cloth and water turned for 14 days.
            Trail length:
   The Trial length will be constructed at least one month advance before starting of concrete paving work.
   Trial length of 60mm with same width, Depth etc as per permanent work will be done at nearer to site.
   Transverse joints and longitudinal joint of each type that are to be included in the pavement work will be constructed and assessed in the Trial length.
 Density:
   At least 3 cores drilled when the concrete is not less than 7 days old.
              11.2 Strength:
   Minimum of thirty (30) beams for flexural strength and thirty cubes for compressive strength will be prepared form the concrete delivered to the paving plant.
   Each pair of beams and cubes will be representing a different batce of concrete.
   Compressive and flexural strength will be after 28 days curing.
   At the age of 28 days thirty cores with diameter 150 mmshould be saw cut from the slab.
   The cores will be saw cut in both ends to provide a specimen height of 300 mm +/-15mm.
              The mix will be designed to achieve
§  The average flexural strength >4.5 +1.65*s(Mpa)
[s=standard deviation]
§  Strength of any sample >fck � 1.65 s
§  The average compressive strength of the cores 0.8/ (Average compressive strength of the thirty cubes.)
            Temperature Measurement:
   The temperature development in the concrete slab should be recorded after every 3 hours during hardening after installment of the thermometer & temperature-age relationship should be determined.
   It should be measured in the middle of the slab (vertically) at a horizontal distance of at least 1000 mm from any free end.
   The temperature should not exceed 70 degree C.
Inspection Dowel Bars:
   Alignment of dowel bars and construction joint shall be checked by measurement relative to guide wires.
   The position of dowel bars, filler board will be measured after carefully exposing plastic concrete across the whole width of concrete.
Preparation of joint and sealing of joint grooves:
   Transverse Joint shall not be sealed before 14 days after construction
   Joint grooves will be constructed to an additional depth / width as mentioned in drawing.
   The groove shall be cleaned and dried at the time of priming and sealing
   All grooves shall be cleaned of any dirt or loose material by air blasting with filtered, oil-free compressed air.
   Before sealing the temporary seal provide for blocking the ingress of dirt, soil etc., shall be removed.
   A height compressible heat resistant paper-backed debonding strip as per drawing shall be inserted in the groove.
   In the case of longitudinal joints, heat resistant tapes may be inserted to block the leakage though bottom of the joint.
Sealing with sealants:-
   The primer recommended by the manufacturer should be applied for sealants.
   Priming and sealing with applied sealants should not be carried out when temperature in the joint groove to be sealed is below 7 deg C.
   If hot applied elastomeric type sealant complying AASHTO M282 is used it shall be heated and applied from a thermostatically controlled, indirectly heated preferably with oil jacketed melter and pourer having recirculation pump and extruder (This is applied at junction of Asphalt and concrete pavements.
   Cold applied polyurethane / Polysulphide type complying BS: 5212-1990Sealan will be mixed and applied according to the time limit specified the Manufacture to the concrete pavements.
   Primer will be applied with an appropriate brush.
   Care such as temperature and time of sealing will be emphasized to avoid any bulge of sealant during contraction of joint.
    Sealant shall be applied slightly to a lower level than the slab with a tolerance of 5+ 2mm.
The type and details of different joints treatment are tabulated below:-
         
TYPE OF JOINT
JOINT
DETAILS & TREATMENT
Polysulphide
Sealant(cold)
Debonding
Strip
3~4
Mm
Groove
Soft
Rope
Butt
Joint
Compressible
Filler Board
Longitudinal
Expansion
Construction
Contraction
Testing of applied Sealant:-
Joint sealant compound and primer should be tested in:
    Cold applied Polysulphide sealant (according to BS: 5212 Part 2)
In case if deliveries are made more frequent than testing may be reduced to every three months.
Measurement of texture depth � Sand Patch Method
   The apparatus as mentioned in MoRTH601.12.1 will be used to measure the texture depth.
   The surface texture will be measured as per the method laid down in MoRTH601.12.1 and the same is recorded in lab format.
Opening to Traffic:-
   No vehicular traffic including contractor’s vehicles will be allowed on the finished surface until a field flexural strength of minimum 4.50 MPa has been achieved where the average flexural strength of minimum 3 specimens should exceed 4.50+1.65 s(s=standard deviation).
   Each series of test specimens for measurement of flexural strength should consist of minimum 3 test specimens.
   Prior to the opening to traffic the joints should be sealed and areas adjacent to the pavement should be completed to a degree that will ensure traffic safety.
Quality Assurance and Control Checks
   As part of Quality Assurance this Segment Quality Plan for PQC has been prepared in line with the specification provided in relevant MoRTH clauses, Contract Supplementary Technical Specification and other Codes/ Standard / Specifications etc. elsewhere mentioned in this Plan.
   As a part of Quality Control all the Inspection and Testing requirements for various activities involved in the laying of PQC will be carried out as per relevant MoRTH Specifications & Contract Technical Specification etc. As described in Inspection and Test Plans attached to this Segment Quality Plan for PQC.
   These Inspection and Test Plans shall consist of the type of Inspection and name of the Test to be conducted for Product Realization, the frequency of testing acceptance criteria and category of Inspection.
   Inspection and Test Plans should be revised whenever there any change in methodology and specifications etc.
Nonconformities in PQC:-
   Any Non-Conformity observed during field Inspection and also during Testing of Materials / mixes / laying system etc. the same should be recorded in the specified Nonconformance Report and necessary Corrective / Preventive actions should be initiated to prevent such things in future.
   QA/QC Engineers are responsible to control the Nonconforming products as described in Procedure, and relevant section-in-charge site engineers are to take appropriate corrective /preventive actions.
   All Product Non-Conformities shall be observed, recorded, corrective/preventive actions and closing of NCR’s should be as per the established documented procedure described in Project Quality Plan.
Safety & Environmental Requirements:
   Hazard Identification, Risk assessment and Risk control measures for each activities and sub-activities involved in the present Segment shall be identified and necessary action plan shall be initiated.
   Environmental Aspects and Impacts associated with various activities and sub-activities involved in the present segment and their mitigation/control measures shall be identified and necessary measures shall be initiated.
SEQUENTIAL OPERATION OF PQC LAYING

DLC layer Approval
Site cleaning, Application of 2nd coat of curing compound as a separation membrane
The survey, Setting out, fixing of String line
Placing Paver and TCM
Clearance to B/Plant for Production of concrete after checking string line & Equipment.
Production of concrete as per the Mix design and adjust as per the requirement

Transportation of Mix to Site
YES
SEQUENTIAL OPERATION OF PQC LAYING

                            
                                     

Reject the Mix and find out Root Cause

 

Check the mix as per the requirement i.e. Slump,     Temperature, Air content
etc and meets as per design?

 

                                                                                    NO     

                                                                                      
                                                                                     

YES
D         Dumping concrete at regular spacing in front of Paver and start paving
Monitoring levels through level sensors.
Fixing of Dowel bars and tie bars by DBI & TBI as per Drawing
Rectification of surface defects (if any) manually by Mesons.
Texturing & curing by TCM and Test rate of spraying.
Fixing of Stopper after End of Day’s Work.
Initial Joint cutting after the setting of concrete
Cleaning of joint and fixing backup rod.
SEQUENTIAL OPERATION OF PQC LAYING

Covering PQC with hessian cloth and water curing for min.14 days.
Removal of hessian  cloth and final joint cutting
Cleaning of joint and providing soft rope, debonding strip, polysulphide sealant, compressible filler board, butt joint as mentioned  in Table-2 in PQC methodology
Test texture depth by Sand Patch Method

Proceed for the next activity

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