Method Statement for Permanent Post Tensioning

Construction, Method Statement

According to the site conditions (temperature, humidity), the constituents of the grout have to be in good conditions during production and injection: • During grouting, the maximum grout temperature is limited to 32 °C. If necessary, water shall be chilled using ice cube. • Cement shall not be exposed to sunlight. It should not be younger than a week, and not older than 6 months. No lump shall be present inside the bag. • All equipment should be in working order and the air compressor should be available in case of emergency. • Fresh clean water buckets shall be available at the mixing plant and grouting vents locations in case of spilling in eyes or skin. 5.4 GROUTING MIXING • Grout components shall be mixed in accordance to grout mix design approved, refer to document: UMRTL1-CP2-0000-MTL-RPT-00208-B. Grout mix proportions for 1 batch, around 70 liters: Proportion Grout (Mix 1) Grout (Mix 2) Cement 2 bags (100 kg) 2 bags (100 kg) Water 34 liters 33 liters Admixture, Sikament NN 1.3 liters 1.4 liters Admixture, Intralplast Z-HV 1 bag (0.6 kg) 1 bag (0.6 kg)

• Grout preparation is done as per following steps: - 1. Water shall be added to the mixer; - 2. Start grouting machine; - 3. Add admixture Sikament NN; - 4. Put Nghi Son PC Type I; - 5. Mix during 2 minutes; - 6. Add admixture Intraplast Z-HV; - 7. Mix during 2 minutes until obtain a uniform thoroughly blended grout; • Once mixed, grout is transferred into a storage tank. Before pumping, fluidity test shall be suscessfully performed. Pumping shall start when the volume available in the storage tank is enough to fill at least one tendon. Note: If the grout has to be stored more than 1hour, a fluidity test at the storage tank has to be done to ensure grout can still be injected. 5.5 CONTROLS The PT Supervisor must ensure that the grout is conforming to requirements. Tests have to be performed on grout to be sure that tendons will be perfectly injected. • Temperature < 32 oC • Fluidity: less than 35 sec in flow cone • Bleeding: 0% in the first 3 hours • Expansion: < 10% • Strength: > 20 MPa at 7 days, > 30 MPa at 28 days • W/C ratio not more than 0.42 5.6 GROUTING INJECTION Note: • Grouting shall be carried out within 7 days after stressing operation. Otherwise the temporary protection (soluble oil coating) of the stressing steel has to be applied by spraying into the ducts and grouting must be applied within 20 days after stressing. • An air testing shall be done before grouting. This test is to identify potential leakage between segment connections. In case of leakage, the pressure will dropped significantly. Refer attachment #4. Before starting pumping, the available volume of grout in the storage tank has to be checked to make sure it is sufficient to fill at least one tendon. Before connecting the pump hose to the inlet valve of the duct, activate the pump to run grout, stop pumping when the grout comes out in a constant flow without water or air.

Note:
• The theoretical volume to be injected is 3.4 liters / meter for 12T15 (duct Ø80mm). A 37m duct will required in theory ± 140 liters of grout. The PT Supervisor has to follow the following steps: 1. Installation of valves, grout vents and grout caps: - Install the proprietary grout cap for the respective PT system. This is done by bolting the cap into the tapped bolt holes in the casting. - The grout cap and the casting have inlets and out lets built into them to attach a HDPE or PE tube of a nominal 20mm diameter. - On this HDPE, tune a tap with closing valve can be attached to close of the out let. 2. Connect the pump hose to the opened inlet valve, by a Camloc link, and secure it. 3. Start the pump. A continuous one-way flow of grout shall be maintained. Grout is pumped through the duct. Grouting of the tendon is performed in one operation without stop. Important: the speed of the grout shall be between 8 and 14 meters per minute.

Grout vents on the recess (Pier Segment) 4. The pump runs until the grout comes out from the outlet vent. The operator pours the grout on the bucket, till a continuous flow of good grout comes out (i.e. until no visible sign of water, oil, or air is detected). Important: the pressure has to be less than 15 bars, during the whole grouting operation. 5. When the quality of grout observed coming out of the outlet is acceptable, the outlet valve is closed as the pump is still running. 6. The pressure has to be raised to 5 bars, and to be held for 30 seconds in the duct. If no leakage appears, the inlet valve could be closed. 7. Disconnect Camloc coupler and connect to following tendon. 8. Then the next tendon could be injected.  

  1. Repeat steps 1 to 7 until full span tendons has been grouted. The operators and their assistants then check the inlet and outlet ends that all valves are securely closed Notes: For more safety, handle of the valves can be removed (remove screw and handle), not to open them accidentally. If soluble oil has been sprayed to protect the tendons, the grout may come out thicker than at the inlet and discolored. The pumping shall be carried on until the discoloration of the grout has been noticeably reduced. When grouting has been paused between two tendons, quality of the grout can be assessed with a fluidity test between before resuming the actual grouting. Important: Valves at both inlet and outlet should not be dismantled before setting of the grout (about 3hours). 5.7 WASHING OF THE EQUIPMENT AFTER GROUTING Important: After each grouting operation, all equipment has to be properly washed, before the end of the working shift. The storage tank and the mixer shall be properly cleaned with clean water and especially at the location of the turbines and of the hoses. Circulate water by pump until everything is cleaned. The pump has to be opened, so as to clean the pump balls as even if the water coming out is clear, there may be some deposit of grout in the pump circuit. 5.8 SAFETY MEASURES All workers have to wear, in addition with standard equipment, safety goggles, dust mask and rubber gloves. In case of flowing of grout on eyes, they have to be cleaned instantaneously with clean water during 1 minute, then clean again by physiological saline. A Hazard and Risk Assessment, enclosed in this document, in Attachment #1, shows the risks of grout injection, and the preventive action that have to be respected.
  2. PROTECTION OF END ANCHORAGES After grouting is completed, exposed end anchorages, strands and other metal accessories shall be cleaned of rust. Then, an epoxy bonding compound shall be applied to all such dry metal surfaces. After application of the epoxy bonding compound the void between the form and the anchorage shall be filled with concrete to protect the anchorage.  
  3. RESOURCES TO BE USED 7.1 EQUIPMENT TO BE USED Equipment to be deployed for the installation of permanent PT. No. Description Specification Quantity Unit Remarks 1 Strand pusher 50m capacity 2 nos 2 Guide pipe 2 nos 3 Flexi tube 2 nos 4 H-speed abrasive cutter or Hydraulic cutter 2 nos 5 Crane 4 ton lifting capacity 1 no For coil lifting 6 Strand coil dispenser 5 nos 7 Strand Bullets Plastic type
    8 Walkie-Talkie 4 nos Note: Above stated type & quantity of equipment could be changed if necessary. Equipment to be deployed for the stressing of permanent PT. No. Description Specification Quantity Unit Remarks 1 Strand Jack CC350 2 nos Freyssinet ZPE19 2 nos VSL 2 Electric power pump P6M 2 nos Freyssinet EHPS 3/4H 2 nos VSL 3 Chain hoist 3 ton capacity 2 Set 4 Hydraulic hoses & connections 700 MPa capacity 2 set 5 Pressure gauge 2 nos 6 Metal ruler
    7 Spray color bomb
    Note: Above stated type & quantity of equipment could be changed if necessary. Equipment to be deployed for the grouting of permanent PT. No. Description Specification Quantity Unit Remarks 1 Grout mixer + pump ZBE 100 or VSL twin drum mixer 1 set 2 Water + pump
    3 Air compressor
    4 Grout hose 1 no
    5 Weighting scale
    6 Cube moulds 50x50x50mm 2 Set 3 moulds for each set 7 Flow cone 1 no
    8 Stop watch 1 no
    9 Thermometer 1 no
    10 Water tank 3000L capacity 1 no
    Note: Above stated type & quantity of equipment could be changed if necessary.   7.2 MANPOWERS TO BE DEPLOYED Organization chart and responsibility for the installation of permanent PT works:

Note: Number of manpower could be changed according to site

7.3 MATERIALS TO BE USED Materials to be used for the installation of permanent PT works as per sections are: No. Description Sources Remarks 1 Strand Provided by Main Contractor Ø15.2mm, 7 wires, class 2 relaxation strand complies with ASTM A416 2 Anchorage FVR VSL type GC6-12 Freyssinet AnC15 3 Ducting by Precast Yard 0.35mm thick, Ø80/87mm ID/OD galvanized corrugated duct 4 Cement FVR Ordinary Portland Cement 5 Additive FVR - Sikament NN - Intraplast Z-HV 6 Water Tap water Water used shall be free from impurities, which can influence the hardening of grout and not contain any substance which may attack the prestressing steel 7 Sika Poxitar F FVR Protection of end anchorage Note: The material shall get approval from Employer’s Representative before commencement of installation of permanent PT work.   8. OCCUPATIONAL HEALTH, SAFETY AND CONTROL The Hazard and Risk Assessment (HRA) has been carried out in the form of the Job Safety Analysis (JSA) to include those activities which are specially associated with the installation of permanent PT. These are reviewed by the HSE Officer to ensure that all the hazards have been identified and adequate control measures are in place. All personnel shall wear the appropriate PPE at all times. 8.1 JOB SAFETY ANALYSIS (JSA) / HAZARD ANALYSIS & RISK ASSESSMENT (HRA / SAFE WORK METHOD STATEMENT (SWMS) In accordance with SCC’s HSE procedure: HCMC-280-0000-HPS-PRO-00034. The JSA has been completed by the FVR JV Technical Department and has been reviewed by the HSE Department. It should also be reviewed by the work crew prior to activities being performed. The document has identified the hazards associated with the activities involved in the installation of permanent PT and details the measures to be adopted to minimize or eliminate those risks identified. Attachment #1 8.2 TOOLS AND EQUIPMENT All tools and equipment for the task shall be in safe condition and fit for its purpose. Where applicable, registration papers, certifications shall be produced and tests certificates will be available for inspection. At the start of each shift, equipment shall be visually checked for mechanical and structural soundness. All equipment shall be carefully examined and all hoses and couplings checked for the leaks and general condition.   9. ATTACHMENTS ATTACHMENT #1: HAZARD AND RISK ASSESSMENT (HRA)   ATTACHMENT #2: STRESSING JACKS Freyssinet C Range The jack used for the Freyssinet PT system is the CC350. Important: This jack has be used only with Freyssinet C Range and Freyssinet P6M pump. Every 6 months the jack has to be calibrated by external laboratory.

VSL GC System The jack used for the VSL PT system is the ZPE19 for 12T15. Important: These jacks have to be used only with VSL GC system and VSL EHPS ¾ H Every 6 months the jack has to be calibrated by external laboratory.

ATTACHMENT #3: GROUTING PUMP

Grouting Pump

FOR INFORMATION ONLY

ATTACHMENT #4: AIR TESTING   In order to check potential leakages (at the cap or at the segment joint), an air test has to be done before grouting. 1. GROUT CAP INSTALLATION Anchorage surface has to be cleaned and exempt from concrete slurry. Permanent grouting caps are fitted and bolted onto the anchorage, and a clamping device is fixed at the back of the cap. An O-ring has to be placed inside the cap groove in order to make the connection between the cap and the anchorage watertight. 2. AIR TESTING Air shall be blown into the duct using air compressor, and a pressure of 5 bar (500 kPa) shall be kept for at least 20seconds. If pressure drops under 4 bar (400 kPa), leakage has to be fixed. The Air Testing is to be repeated after repair. Air testing shall be recorded on the Grouting Record Sheet.

Check that there is no blockage inside the grout vents by randomly open them one by one. If required, oil present into the tendon can be flushed out with compressed air.   ATTACHMENT #5: FRICTION LOSS COEFFICIENT   ATTACHMENT #6: EXAMPLE OF JACK CALIBRATION CHART