MISC STRUCTURAL REPAIRS AND STRENGTHENING TO CERTAIN OTM AND MD ACCNS AT NORTH OF RAILWAY LINE UNDER GE MISSAMARI

Examining concrete by tapping with light hammer and marking of the loose concrete areas of structural elements in straight line geometrical forms, grooving the edges same with grinder upto 5-10mm depth without damaging existing rebars, carefully removing unsound weak/loose concrete/cover & concrete around the rebars upto 10 mm depth by low impact high frequency hammer/chipper without damaging the sound concrete, daily cleaning and stacking of debris at prescribed location in polypropylene/ paper bags, disposing off the debris outside the premises, complete all as directed.

Providing & applying a two components ready to use polymer modified cementatious coating certified for portable water in three coats with glass fiber mesh of =>45 GSM inside of the wall & floor of the tank.The thickness of coating shall not be less than 1.5mm complete all as manufacturers instruction and as directed.

M&L applying three coats water based epoxy coating certified for portable water on all over the concrete surface from inside, the coating shall be applied using roller brush application complete all as manufacturers instruction and as directed.

M&L making V groove of 10mm wide and 30mm deep or upto the extend of joint/crack present at site over joint/ crack line using electricity operated angle grinder with diamond concrete saw blade and cleaning it by air blower complete all as manufacturers instruction and as directed. Note:-The groove shall be cut on the concrete surface along the joint/crack over RCC structure to be repaired.

M&L Sealing of exposed 'V' groove of 10mm wide and 30mm deep solvent-free, moisture tolerant, thixotropic, two part structural adhesive and epoxy repair mortar cum surface levelling mortar complete all as manufacturers instruction and as directed.

M&L Drilling Holes of 12mm dia up to 100 mm deep holes in structural members at the interval of 300 mm in staggered manner or along the joint & crack line in Reinforced Concrete (RC) structural element including cleaning of the holes by air blower and inserting 12mm dia NRV (Non Returnable Valve) nozzle compatible with epoxy injector and having machined external end to receive outlet of Grouting Gun. Fix inside the hole by applying thixotropic epoxy adhesive to ensure complete sealing and allow curing the system for minimum of 8 Hrs before Grouting including nozzle projections, excess putty, if any, over concrete element by grinding, leveling and finishing the external surface, after completion of the work, etc. complete all as manufacturers instruction and as directed.

M&L Grouting injecting two part, low viscosity, moisture insensitive injection-liquid at damp substrate location, based on high strength epoxy resin by pressure and using pressure epoxy injector with accessories till nozzle refused to accept the grout including mixing of grout having Mixed Density 1.1 kg/l (at +27°C); Viscosity ~ 500 mPas at +30°C and should comply according to ASTM C 882 and should have below properties. Compressive strength >= 50 N/mm2 (7 days) according to ASTM C 579; Tensile Strength ~ 30 N/mm2 (after 14 days at +30°C cure) (According to ISO 527); Tensile Adhesion Strength >8 N/mm2 (failure in concrete) after 14 days at +30°C cure. Seal the nozzle with thixotropic epoxy putty after the refusal of grout material from the nozzle complete all as manufacturers instruction and as directed. Note: leakage through other nozzle or cracks are required to be monitored while grouting and such points to be sealed as and when required without any extra cost.

M&L Prepration of existing surfaces like chipping of unsound weak/loose concrete/cover of reinforcement and removal of debries to a designated location (upto full height) block to support the structure proisionally during repair work and maintaining them in positioin till required, complete all as manufacturers instruction and as directed.

M&L cleaning existing reinforcement with wire brush/rotary wire brush to make surface free from rust scales, loose material, dirt etc complete and applying two coats of alkaline rust converting primer rust remover with brush on the existing rebar for complete wetting of rusted metal surface and allowed to react it for 16-24 hours. After 24 hours, a white layer will appear which will protect further corrosion of metal / steel for about 5-7 days including surface preparation. Before applying protective coating, the surface should be wire brushed and thoroughly cleaned for dust with dry cloth, complete all as manufacturers instruction and as directed.

Providing and Application of as passivator/Anti corrossion coating to the steel reinforcement shall be applied. The material shall be two component,cement based polymer modified two component coating for corrosion protection.The material shall be prepacked and ready to use. It shall be fully compatible with the reinstatement methods adopted complete all as specified and as directed by Engr-in-charge.This shall include surface preparation and errection of steel porps as required for the application complete all as manufacturers instruction and as directed.