Structural Repair and Non-destructive testing of 120 meter high RCC stack

Part-A Pre Repair (NDT) Rebound Hammer Test (RH): Conducting Rebound Hammer test,at all specified locations prepared after chipping the plaster (till the concrete surface) ,on structural members (columns, beams,slab & walls,shells,etc), for determining the estimated compressive strength of concrete and uniformity of concrtete as per latest BIS/ASTM standards etc. Complete all as per specifications and as directed by Engineer-In-Charge.

Ultrasonic Pulse Velocity Test (UPV) : Conducting ultra sonic pulse velocity test, at all specified locations prepared after chipping the plaster (till the concrete surface),on structural members (columns, beams,slab & walls,shells,etc). to assess the intigrity of concrete as per latest BIS/ASTM specifications etc. Complete all as per specifications and as directed by Engineer-In-Charge.

Core Test : Extraction of (75mm dia) concrete cores from specified locations and testing for compressive strength, water absorption & unit weight. The quoted rate shall include charges for filling back the core holes with polymer modified mortar/Micro-concrete and finishing etc. Complete all as per specifications and as directed by Engineer-In-Charge.

Half Cell Potential Test (HCP) : Conducting half- cell potential meter test at all specified location to assess the risk of corrosion including exposing the reinforcement for carrying out the test. The test shall be conducted as per latest BIS/ASTM specifications. The quoted rate shall include charges for filling back areas chipped for exposing the reinforcement with polymer modified mortar/Micro-concrete. Complete all as per specifications and as directed by Engineer-In-Charge.

Rebar Mapping: Conducting Profometer scan at all specified location of the structure for reinforcement steel location, size, spacing between reinforcement and concrete cover measurement, etc.Complete all as per specifications and as directed by Engineer-In-Charge.

Chemical Test: Chemical tests on concrete in the laboratory to determine the parameters to understand the chemical deterioration/ degradation of concrete and its effect on reinforcement corrosion are: i) PH value (to check alkanity of concrete ). ii) Water soluble chloride content % ( by mass of concrete ). iii) Concrete total sulphate content.

On core

On dust sample

Note : Extraction and testing of concrete drill dust samples from the structures. 3 drilled samples from depths 0- 15mm , 15-30mm and 30-45mm shall be collected from each location.

On core

On dust sample

Carbonation test : To evaluate the depth of carbonation in the RCC structure, carbonation test shall be perform as per latest BIS /ASTM standard procedure carbonation test shall be carried out on specified dust samples. Depth of the carbonation shall be evaluated on concrete core separately.Complete all as per specifications and as directed by Engineer-In-Charge. Note:-The test shall be performed to determine the depth of concrete affected due to combined attack of atmospheric carbon dioxide and moisture causing a reduction in level of alkanity of concrete

Linear Polarization Test: (LPR): Conducting Linear Polarization Test: (LPR) for determining the estimate rate of corrosion as per the latest BIS/ASTM standards. Complete all as per specifications and as directed by Engineer-In-Charge. Note: The quoted rate shall include charges for filling back areas chipped for exposing the reinforcement with polymer modified mortar/Micro-concrete. Complete all as per specifications and as directed by Engineer-In-Charge.

Part-B Structual Repair Providing, Erecting, Maintaining And Removing Temporary Protective Barricading/ Screen Of 1.8 M In Height Made In Panels With Each Panel Having Minimum 40x40x6 mm Size MS Angle Frame With Minimum 24 g Thick G.I Corrugated Steel Or Suitable Stiffened Plane G.I Steel Fixed On One Side Of The Frame. Such Panels Shall Be Interconnected To Each OtherWith Nuts And Bolts, Fixed To Ground Firmly, At About 2m Spacing For The Work Duration As Required By The Engineer-in-Charge.

Submission of Report : Providing, Erecting, Maintaining And Removing Temporary Protective Barricading/ Screen Of 1.8 M In Height Made In Panels With Each Panel Having Minimum 40x40x6 mm Size MS Angle Frame With Minimum 24 g Thick G.I Corrugated Steel Or Suitable Stiffened Plane G.I Steel Fixed On One Side Of The Frame. Such Panels Shall Be Interconnected To Each OtherWith Nuts And Bolts, Fixed To Ground Firmly, At About 2m Spacing For The Work Duration As Required By The Engineer-in-Charge.

Steel Prop Of Up To 5 MT Capacity And Up To 3.2m Height

Providing and fixing double Tubular scaffolding system using HFrames / APS system or (cup lock type) on the exterior side upto 120m height and 6.7m dia at bottom & 3.462 dia at top (approx) of RCC stack for conducting tests and structural repairing etc. Scaffolding made with minimun 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 there after. The scaffolding system shall be stiffened with bracings, runners, connection with building/structure 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 payment shall be made once irrespective of duration of scaffolding

Full height of 120m RCC chimney for entire working period including de-scaffolding

Safety net to be provided around the structure/scaffolding as per site requirements and as directed at site.

Propping And Supporting The Structural Members And It’s Adjoining Areas With Steel Props (Adjustable Or As Required), Bracings, Steel / Timber Runners etc. To Relieve The Structural Member Of The Required Load Coming Over It As Per The Pattern Given By The Contractor & Approval By Engineer-in-Charge Complete.

Providing, erecting, operating lifting arrangements for material and personnel movement for day to day work and inspection of works with proper supporting arrangements, safety arrangements/ anti fall devices including guard rails etc. complete for entire working period and dismantling the same. Note: 1) Detailed schematic drawing, design data for scaffolding and lifting/ hoisting arrangements shall be submitted by the contractor after getting its design vetted from Government agencies like IITs, NITs, SERC (Structural Engineering Research Center, Chennai) or reputed Government Engineering Colleges etc. and got approved by the Department (NRB) before erection at site. 2) Design Basis Report and Design Report for scaffolding shall be got approved from departmental regulatory authorities (BSC) before erection.

Dismantling old ceiling/ landing plaster carefully and cleaning the surface for plaster, disposal of rubbish to the dumping ground within 200 m lead etc. complete as directed by the Engineer-in-charge

Lead charges for Lead Exceeding 1 KM but not exceeding 2 KM, by mechanical transport including loading, unloading, from 120m height and stacking / levelling etc.

Debris Beyond 1 Km but up to and including 2 km

Dismantling the RCC surface by chipping or breaking wherever required to remove loose particles, fungus, spalled/ loose concrete and cleaning the reinforcement etc. and cleaning with mechanical grinding, wire brush, coir brush, carefully and washing the surface with high pressure water jet with suitable pressure to obtain dust free surface at all heights and as directed by Engineer-In- Charge. Note : Disposing and stacking debris with in 100m lead or as per directed by Engineer-In- Charge.

Drilling and installing the 16 mm dia holes (nozzle spacing should be as per the drawing) about 100 mm to 200 mm deep on the surface of the member at staggered pattern . Cleaning the holes with compressed air and spiral brush to make it free from drill dust. Fixing twin lock nozzles of 15 mm original dia (to sustain pressure up to 10 kg/cm2) in 16 mm dia holes and sealing the nozzles with epoxy putty, complete all as per manufacturers specifications and as directed by Engineer-In-Charge.

Cutting 'V' groove of 10-12 mm wide and 15 mm deep if cracks found in RCC surfaces and cleaning the surface by blowing compressed air and washing with water jet to make the area dust free, sealing the "V" grooves with epoxy putty as per specification in tender book, manufacturers specifications and instruction of Engineer-In-Charge.

Providing and injecting lean cement grout into separation joints /cracks /honeycombed areas with grouting pump at a pressure @ 1.5 to 3.5 Kg/cm2 as per specification in tender book through the above nozzles. Once grouting is completed after 24 hours, cut the nipples and seal them with Epoxy Putty complete all as per manufacturers specifications and as directed by Engineer-In-Charge.

Drilling of 12mm dia (nozzle spacing should be as per the drawing) about 100 mm to 200 mm deep on the surface of the member at staggered pattern . Cleaning the holes with compressed air and spiral brush to make it free from drill dust. Fixing Aluminum packers of 10 mm original dia (to sustain pressure up to 10 kg/cm2) in 12 mm dia holes and sealing the nozzles with epoxy putty, complete all as per manufacturers specifications and as directed by Engineer- In-Charge

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. Length of reinforcement bars clean of rust all around shall be measured for payment. Applying alkiline chemical rust remover with paint brush and removing loose particles after 24hrs of its application with wire brush and thoroughly washing with water and allow it to dry complete all as per manufacturers specifications and as directed by Engineer-In-Charge.

Application of two coat anticorrosive epoxy coating for bar protection against future corrosion. Coating is for old as well as newly provided steel. This system once applied on steel shall provide extended protection against future carbonation and chloride attack. complete all as per manufacturers specifications and as directed by Engineer-In-Charge.

Drilling and providing reinforcement by anchoring in existing RCC structures by drilling specified diameters of bars and anchoring with anchor resin of approved equivalent make after cleaining the holes to make dust free complete as per specifications and directed by Engineer- In-Charge. (only No. of anchorix will be measured and paid, reinforcement will be paid under relevant item).

Providing and injecting low viscosity Epoxy Grout {two components low viscous high strength (7 days comp strength 800 kg/cm2)} into separation joints/ cracks/ honeycombed areas under pressure of 2 to 7 Kg / cm2 with as per specification in tender book through the above nozzles. Once grouting is completed after 24 hours, cut the nipples and seal them with Epoxy Putty complete all as per manufacturers specifications and as directed by Engineer-In-Charge.

b)12mm dia bars in 14mm dia holes or size of holes as recommended by the manufacturer of rebar anchor.

c)16mm dia bars in 18mm dia holes or size of holes as recommended by the manufacturer of rebar anchor.

Providing Reinforcement for reinforced cement concrete at all levels including supplying, preparation of bar bending schedules,cutting, bending, transporting, fixing, tieing in position with 1.6 mm dia soft drawn annealed binding wire all labour charges, cost of cover blocks in specified grade of concrete etc. complete including cost of binding wire as per specifications and drawings. Steel Supplied by the Contractor

a) 10mm dia bars in 12mm dia holes or size of holes as recommended by the manufacturer of rebar anchor.

Fixing reinforcement by using welding (electrodes of grade 7018 or approved equivalent grade) to the required length and lappages etc. as per site conditions and as directed at site.

Upto and including 32mm dia reinforcement: Using TMT bars of specified grades. TMT bars to be supplied by vendors as per specification in tender book using virgin materials. Note: Steel shall be TMT bars of sizes as required . Binding wire required for the work will have to be supplied by the contractor and work shall be carried out upto 120m height at their own cost and will not be measured for payment.

Carry out application of 'Bi-polar migratory corrosion inhibitor on overall exposed concrete surface with the help of brush or low pressure air spray. Number of coats to be applied depends on the porosity and moisture content of the substrate and the weather conditions, normally 3 to 5 coats are necessary to achieve the required consumption i.e. 4ltr./ m2. Time between two coats shoud be 30 mints.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. complete all as per manufacturers specifications and as directed by Engineer-In-Charge.

Providing & applying one coat of Epoxy Bonding agent as per specification in tender book for bonding on the existing concrete surface with new surface prior to polymer/ microconcrete as per manufacturers specifications and as directed by Engineer-In-Charge.

Providing, mixing and applying ready mix polymer modified cement mortar in layers each layer not exceding 25mm thick, including trowelling with wooden tools etc. Each layer of 25mm shall be measured for payment.Bond coat should be applied after each sucessive layer.Complete all as per manufacturers specifications and as directed by Engineer-In-Charge.

Providing and fixing shear key of 10mm dia upto 200mm depth to be embedded in concrete with anchor resin/epoxy as per directive of Engineer-in-charge.

a) Upto 50mm average thickness with out aggregates

b) Above 50mm admixed with 10mm down cleaned washed aggregates @ 50% by weight.

Providing and fixing of special quality water tight shuttering for placement of Microconcrete including necessary strutting, proping, staging, supports etc and deshuttering the same after the specified time.

Providing 20 mm thick External plastering in two coats under layer 12 mm thick with C.M 1:4 (using crushed sand) finished with a top layer 8 mm thick in C. M 1:3 (using crushed sand) including approved water proofing compound @ 2% by weight of cement or as per manufacturer's specifications, sieving of sand to required fineness, scaffolding up to 10 metres height, finishing, curing etc. complete as per specifications. and as directed by the Engineer-in-charge

Providing & applying two coats of UV resistant Acrylic Anti - Carbonation Coating with solid content of 60% as per specification in tender book for external surface over a coat of primer and over a base of putty over one coat of two pack epoxy based primer after structural repair and surface preparation as per manufacturers specifications / Data sheet complete.

a) Epoxy bond coat as per specifiation in tender book as per site requirements and manufacturers specifications over prepared surfaces.

b)Providing epoxy putty using as per specifiation in tender book as per site requirements and manufacturers specifications over prepared surfaces.

c) Providing and applying one coat of primer and 2 or more coats of UV resistant Acrylic Anti-carbonation coating with solid content fo 60% of as per specifiation in tender book as per site requirements and manufacturers specifications over prepared surfaces of minimum 140 micron dry film thickness .

Providing cement based water proofing treatment to the new terraces, chajjas, cleaning the concrete surfaces, giving injections to the top slab as required with cement and approved waterproofing compound solution to fill up all inherent holes, voids, honeycombs etc. in the concrete slab, setting brickbat coba in waterproof mortar with necessary gradient for easy flow of water and continue the treatment along the inner faces of parapet or other adjoining wall up to a height of 300 mm in thew shape of vattas, with waterproof plaster finished smooth with trowel in cement / geru with false markings of 300 mm squares complete as directed by the Engineer-incharge

Average 65 mm thick for chajjas using river sand / crushed sand

Providing and placing in position M-30 grade super fluid micro-concrete, which shall be cement based prepacked single component, cloride free, non shrink, free flow, self compacting, ready to use after mixing water in specified proportions obtained from approved manufacturer as per specification and direction of Engineer-In-Charge.

Providing Chemical based water proofing of modified acrylic emulsion Polymer and Elastomeric waterproofing coating as per specifiation in tender book over terrace slab/ parapet/ side walls etc. at all elevations including polycon based fibrous net complete including cleaning and preparation of surface and testing by ponding water complete with following operations. 1. Removing of all loose materials by wire mesh and clean entire terrace with clean water by using water jet wherever required.

2.Open all visible crack by plaster cutting machine in "V" shape 3. Dilute binder with water in the Ratio of 1:4 and pour on the bare slab to be treated 4. Apply binder and cement in the ratio of 1:1 and water to obtain paste like consistency and fill the cracks. 5.Apply bond coat of binder and cement in the ratio of 1:1 to entire terrace. 6. First coat of binder & cement at the rate of 1.48sq.m per litre of Indofil 7.Lay polycon based firous net (polyester geotextile of minimum 80 GSM) for entire area immediately before drying of first coat to get proper bonding 8. Apply one miore coat of binder & cement above fibre net 9. Apply 2 coats @ 2.40 Sq.M per litre with dilution 10% weight of potable water. 10.Test the surface for water tightness

Sprinkling of river sand on the wrapped surface after rectifying air voids, if any to make the surface rough to take any further finishes.

Providing and fixing on wall face unplasticised rigid PVC rain water pipes conforming to IS:13592 Type A including jointing with seal ring conforming to IS: 5382 leaving 10 mm gap for thermal expansion, (i) single socketed pipes 75 mm diameter

Dismantling steel work in single sections including dismantling and stacking within 100 m lead In R.S Joists, Angles etc.

Providing and fixing hand rail using 304 grade Stainless Steel pipes of approved size and make and quality by welding, mirror / matt polishing, fixing at site etc. for balcony railing & staircases railing including special sections as per drawings, specifications. complete as directed by the Engineer-in-charge

Part-C Post Repair (NDT) Rebound Hammer Test (RH): Conducting Rebound Hammer test,at all specified locations prepared after chipping the plaster (till the concrete surface) ,on structural members (columns, beams,slab & walls,shells,etc), for determining the estimated compressive strength of concrete and uniformity of concrtete as per latest BIS/ASTM standards etc. Complete all as per specifications and as directed by Engineer-In-Charge.

Ultrasonic Pulse Velocity Test (UPV) : Conducting ultra sonic pulse velocity test, at all specified locations prepared after chipping the plaster (till the concrete surface),on structural members (columns, beams,slab & walls,shells,etc). to assess the intigrity of concrete as per latest BIS/ASTM specifications etc. Complete all as per specifications and as directed by Engineer-In-Charge.

Core Test : Extraction of (75mm dia) concrete cores from specified locations and testing for compressive strength,Tensile strength, water absorption & unit weight. The quoted rate shall include charges for filling back the core holes with polymer modified mortar/Micro-concrete and finishing etc. Complete all as per specifications and as directed by Engineer-In-Charge.

Compression Test

Tensile Test

Evaluating the performance of post-installed Rebars in concrete as per ACI 355.2.Complete all as per specifications and as directed by Engineer-In-Charge.

Carbon Fiber Reinforced Polymer (CFRP) wrapping: Supplying & applying carbon FRP wraps on external concrete surface of stack as per the manufacture and technical specifications with the following procedure:- a. Applying compatible primer on the prepared substrate and allow it cure for 12Hrs.(Min), Wrapping of unidirectional carbon fiber sheets (minimum 300gsm density) on to the prepared RCC surface in Vertical orientation (1st layer) impregnating with carbon fiber matrix system using tamping roller to avoid any voids etc. of approved make as per manufacturers specifications and as directed by the Engineer-in-charge, ensuring that the fiber does not deviate by more than one degree from the intended direction, vertical and horizontal lapping the sheets not less than 150mm, along the width of sheets removal of all air bubbles and resin pockets by application of gentle pressure by created rollers and ensuring no fiber damage and no peel off at the ends of the sheets generally as per physical properties & technical specifications. a) Properties of carbon fibre (high strength) used in FRP system (as per ACI 440.2R-08) Property Value Ultimate strength ≥ 3.79 GPa Rupture strain (in %) ≥ 1.4 % Elastic modulus ≥ 220 GPa Fibre density (gm/cm3) ≥ 1.5 Fibre area weight unit area ≥ 300 gsm Carbon Fibre fabric width ≥ 500 mm b) Properties of CFRP laminate (high strength) used in FRP system (as per ACI 440.2R-08) Property Value Ultimate tensile strength in primary direction ≥ 1020 MPa Rupture strain (in %) 1.0 to 1.5 % Young’s modulus ≥ 100 Gpa