Retrofitting and structural repairing of security towers

Amount

PART-1 PRELIMINARY PREPARATION WORK: 1. Providing and fixing double tubular scaffolding system using H- frames with cup lock type on the exterior side upto seven story height made with 40 mm dia M.S. tube 1.5 m centre to centre horizontal and vertical tubes joining with cup and lock system with M.S. tubes, M.S. tube challies, M.S clamps and M.S staircase system in the scaffolding for working platform etc. and maintaining it in a serviceable condition for the required duration as approved and removing it thereafter. The scaffolding system shall be stiffened with bracings, runners, connection with building etc. wherever required for inspection of work at required locations with essential safety features for the workmen etc. complete as per directions and as approved by the Engineer -in - charge. The elevational area of the scaffolding shall be measured for payment purposes. The payment shall be made once irrespective of duration of scaffolding

2. Dismantling old plaster / skirting carefully , raking out joints and cleaning the surface for plaster including disposal of rubbish to the dumping ground within 100 m lead

3. Chipping of existing loose and damaged cover concrete at specified locations (including non load bearing members) up to the concrete core with chisel & hammer, cleaning the surface with wire brush and washing concrete surface with water etc. complete as per specification and as directed by the Engineer-in-charge

4. Dismantling of RCC works including Cutting and stacking of steel reinforcement bars and disposal of unserviceable materials within 100 m lead as per direction of Engineer-in-charge

5. Opening of separation gap between RCC members and brick work/block work with electric cutter and removing all loose and deteriorated mortar between the same all complete as per specification and as directed by the Engineer-in-charge

PART-2 STRUCTURAL REPAIR: 1. Application of rust converting alkaline primer: Thoroughly clean the corroded reinforcement/steel rebar by wire brush or rotary grinder. Remove all the corrosion scales present on the bare and reach up to sound steel. Apply of rust converting alkaline primer on corrosion affected steel bars after removing all the scales. It is alkaline in nature and convert both hematie & magnetite compounds in to stable compounds. The matrial shall pass minimum 400 alternate immersion cycles of 2 minutes in 3.5% NaCl solution at room temperature.

2. Application of primer shall be followed with application of two coats of IPNet- RB (confirming to CBRI requirement) anticorrosive epoxy coating for bar protection against future corrosion. Coating is for old a well as newly provided steel. This system (Interpenetrating polymer network system for rebars: IPNet-RB) once applied on steel shall provide extended protection against fiuture carbonation and chlooride attack. The matrial shall pass minimum 720 hours as per ASTM- B- 117 and shall confirm to IS 2770 PART I and ASTM 3963-86.

3. Carry out application of 'Bi-polar migratory corrosion inhibitor on concrete surface by brush in two coats. This inhibitor has migratory kind of property which permits the material to migrate to a virtual extent of 60 mm, through pores of concrete, inhibiting the corrosion and de-passivating the electro - chemical reaction. It has property to attack anode as well as cathode, which is purely alkaline in nature (pH-9.5). Material shall have evaluated test reports indicating significant reduction in corrosion rate after minimum 90 thermal cycles at 60o Centigrade followed by 8 weeks of accelerated corrosion indicative of it's suitability for tropical applications. Grout the corrosion inhibitor in case of excessively damaged RC sections by drilling 50 to 75 mm deep holes at the spacing of 350mm c/c with the dosing of 100ml per hole in concrete body.

4. Providing and applying raw polymer Bond Coat to all exposed concrete surface and rebars prior to polymer treatment complete or as directed by the consultant.

5. Providing and applying ready mix polymer modified repair mortars of approved make to RCC surface duly treated as above with appropriate thickness.

6. Drilling straight/inclined holes up to 200 mm depth and up to 20 mm diameter in concrete/masonry using electrically operated drilling machine, etc. complete. Providing and injecting with grouting pump in sockets at all floor slabs, beams, columns, walls, etc. with cement slurry adding non-shrink grout material of approved brand as per the manufacturer's specification wherever directed by the consultant, cutting the projected socket portion & sealing the same etc, complete as per specification and as directed by the Engineer-in-charge

7. Providing SFMC Micro concrete for strengthening of structural members including mixing, pouring, curing as per manufacturer specifications and as directed by the Engineer-in-charge

7.1 Using SFMC with 50% Quartz aggregate by weight (Only SFMC consumed alone will be measured for payment)

8. Providing and laying superfluid micro-concrete of approved brand mixing with 10 mm to 5 mm size quartz aggregate or sand in the ratio of 1 part superfluid micro-concrete to 0.50 part of quartz aggregate or sand by weight including machine mixing, etc. complete or as directed by the consultant.

9. Providing Reinforcement Steel for reinforced cement concrete at all levels including supplying, preparation of bar bending schedules, cutting, bending, transporting, fixing, tieing in position with PVC coated G.I binding wire, all labour charges, cost of cover blocks in specified grade of concrete etc. complete as per specifications and drawings. Steel supplied by the contractor

9.1 Using TMT bars of specified grades of all sizes. TMT bars to be supplied by the contractor from the own plants of SAIL, RINL or TATA make only using virgin materials

10. Securing & anchoring and welding it at both ends by drilling holes, inserting the ends and grouting with non shrink grout putty/epoxy grout wherever necessary etc. all as directed by the Engineer-in-charge

11. Providing and laying in position Reinforced Cement Concrete (RCC) of Grade M-25 using 20mm maximum size aggregates and crushed sand of approved quality including admixtures of approved brand and quality (plasticiser or super plasticiser) if required, including weigh batching, mechanical mixing, transporting, placing, vibrating, consolidation, finishing, curing etc. complete but excluding the cost of centering, shuttering and reinforcement complete as per specifications above Plinth Level

12. Removing loose concrete from the column, cleaning the exposed bars with wire brush, applying rusticides & rust passivator to the existing bars, providing new reinforcement bar with rings and shear key to the column, applying bond coat to the concrete surface, poring M:25 concrete with minimum thickness 3" to 4", with shuttering, curing, with footing, breaking PCC and redoing the Soling, PCC etc. complete. Measurement will be paid as per perimeter of the column x height of the column jacketed.

13. Providing and fixing shear key to be embedded in concrete with araldite/epoxy.

14. Upgradation of strength using non-metallic composite Fiber wrapping system comprise of bi-directional Goldbond 1893 System of Fiber (900 GSM) and compatible Saturant, by dry lay-up system. Surface preparation: Grinding/ moulding concrete substrate, cleaning it with wire brush removing oil, laitance if present complete. Profiling: Applying compatible primer on the entire pipes using rollers complete Wrapping: Wrapping the fiber sheet to structural element at desired orientation using tamping roller to avoid any air voids etc. repeat the same procedure for multiple layer with the interval of 8 hrs. Second coat of Saturation for RCC Members: Applying second coat of Goldbond 1893 Saturant after min. 12 hrs, rectify air voids if any.

15. Insertion of POWRTHROW sustained release Corrosion inhibiting caplets which shall protect both anodic & cathodic sites and reduce Corrosion potential Ecorr by minimum 80 mV in conductive medium, by drilling 25 mm holes into the concrete at a depth of 30 mm and inserts to be filled by EPCO-PC-Putty.

16. Providing Structural steel work using angles, channels, joists and other sections, welded and / or bolted in built up sections for trusses , structural steel floors, frame works, monorails and other structures including supplying, cutting, welding, fabricating, hoisting, fixing in position, applying a priming coat of approved steel primer etc. complete all as per specifications, drawings and as directed by the Engineer in charge

16.1 Up to and including 300 mm Joists, 350 mm channels, and below sections using materials produced by SAIL / RINL (Vizag Steel) / TATA. All test reports to be provided along with the supply of the materials

Part-3 Civil Works 1. Providing 20mm thick plastering using Ready mix external Plastering compound of approved make for external faces of brickwork / concrete surfaces including prepairation of the surface, curing, cleaning, scaffolding up to 10 metres height complete all as per specification including forming drip moulds wherever necessary and as directed by the Engineer-In-Charge.

2. Providing and applying and finishing walls with two coats of premium fine textured exterior paint of required shade over new work including base coat of water proof cement paint, prepairation of the surface, scaffolding complete as per specifications and as directed by the Engineer-In-Charge.

2.1 On Plain plastered/ concrete surfaces

NAVNATH SUKHDEV LANDGE