Repair &Grouting of Railway Tracks(Sector-Railways)

As per DMRC specifications and guidelines (Usage and need of proper construction chemicals during supply/installation, testing and commissioning of ballastless track

Bolt Grout-Usage of proper 3 component thixotropic epoxy grout
Turn Out Grout
Cracks on Apron-Usage of 2 component Low viscosity epoxy injection grout
Rails Coating-Usage of Zinc rich epoxy primer based coating for anti corrosive behaviors
Cold Joint Application-Usage of bonding agent and epoxy grout
Usage of PC base hyper plasticizers for plinth/apron concrete(M-35 grade)

History

As per the site visit & structural detailing vide structural drawing provided by DMRC we have concluded the rail track of DMRC for Phase-3

The Sub base Part:- The Entire Rail Trade for Metro lines are laid over viaduct/U-G line of precast concrete of M50 Grade concrete with arrangement of Mechanical means as specified by DMRC
APRON: The Apron Laid as M35 Grade Concrete in Rectangular Geometry of width --------, Thickness__________ with difference in pair of concrete at regular interval of 30Metres – 50Metres, The concrete laid over the viaduct is as bonded system/ isolated system somewhere to transfer cyclic and vibrational Load, the loading pattern & cyclical stresses developed on the concrete part is designed & approved by DMRC.This M-35 grade of concrete is extremely critical and requires high long term strength/durability and free from any cracks,hence high water reducing (upto 35% water reducing) PC base hyper plasticizers should be used instead of SNF based admixtures
The Rails: The Rails are HCS (High Carbon Steel ) with its Fixtures as specified by the sleeper and ballastless track Manufacturing Company specified and approved by DMRC
Objective of the study: The objective of KCPL lie with the following observation /opinion after witnessing cracks developed in the freshly made track concrete as well as to suggest remedial measures for laying of new track systems by engaging proper usage of various construction chemicals- Epoxy base/Polyurea Base and others

The cohesive weariness of concrete with the heterogeneous material

Concrete and Bolts (MS/SS)
Concrete & any other Building material.

As the deficiency stated above concrete shows delaminated/non bonding behavior all across the Bolt pockets and any fasteners used, which is a basic property one can visualize with the property of concrete.

Grouting of Anchor Bolts using 3 component thixotropic epoxy grout

SAW cutting of groves all around the geometry of concrete and heterogeneous material with controlled cutting/Drilling/ as per KCPL norms approved by E&C-DMRC
The depth of cut to be 1/4 th to ½ the thickness of element for Mechanical anchorage
Cleaning of saw cut by mechanical or manual means as per approved means using proper tools-It should be free from any external particle
Providing & laying thixotropic Epoxy free flow Grout epoxy ( KUNAPOXY GROUT-3 EP )-3 component thixotropic free flow epoxy grout with exceptional high strength and bonding properties.
Consumption may vary with depth of cut but should be between0 .75 KG to 1.5 Kg, per bolt for proper contact area, anchorage & transfer of vibrational loads on the track
Allowing the system to gain its optimum technical property (specified as 48-72 hours post natural cured)

Construction Joints: Before next pour of concrete

Cleaning of surface to remove all loose lattinces/dust/grease before new pour of concrete and application of SBR based (KUNABOND- Latex base bonding agent
After 3-7 days of continues pour of concreting a groove of size 4mm needs to be cut in any geometry and it has to be left so that exothermic reaction occurring in concrete releases through this cut joint cleaning.
Filling it with highly flexibale. Polyurea base filler materials /epoxy (resilient epoxy based material)- KUNAFIX 80 .This is far superior than any Polysulphide or PU sealants for expansion joints. This is must to be put for sensitive track structures as construction joints have to be properly sealed to avoid any thermal expansion

Consumption 2 cartridges of 600 ML each would be used in 1 joint. On approximation 1 km will have 35 such joints and around 70 cartridges of 600 ML Polyurea systems would be used

KUNAGROUT-GP (Cement grout) or KUNAPOXY Grout-3EP (Self leveling epoxy grout mortar) should be used for all pockets and foundations

KUNACURE-P (Wax base concrete curing compound) –It should be applied on entire apron surface to reduce water losses

Anti corrosion coating on track rails

Sand blasting of track as per approved norms by DMRC
Cleaning of the surface by manual or mechanical means as specified by DMRC
Application of Two component Zinc rich epoxy primer coating (KUNAPOXY-ZN), which gives excellent anti corrosion property to rails and increases abrasion resistance.
It will be applied in 100 micron thickness using airless spray Machine.

Analysis of Challenge occurred

As the structure with above said detail is having leakage/seepage/dampness because of following reasons as observed

The leakage within the structure is continuous, less in summer season and highest in rainy season which is indicative of following

Catchment area of the terrain has some water body/reservoir/fissures etc which with natural course gets into the structure through cracks/fissures/cold joints/lift joints/pinholes/honeycombs etc and splashes trough the tunnel through the plates field welded/shop welded joints or any other cracks in the plates.
Waterproofing at the time of construction has failed to arrest to prevalent condition and due to available geological /Hydro behaviour
RCC, as lining has shrinkage cracks/hairline cracks. Also the joints in RCC- Construction/Cold/Lift/expansion have been fissured resulting in seepage of water.

Problems Encountered

Perennial Seepage of water from multiple points which increases in rainy seasons and winters.
Corrosion of Iron Sheets
Freezing of seepage water, which makes movement extremely difficult and slippery during winters

Activity flow chart to carry out final assignment

Surface Preparation-The area under leakage treatment has to be well repaired surface by mechanical or manual means (Sand Blasting/scarifying) to remove all loose lattinces, dirt,dust,corrosion,rust,formation of Ferrous oxides extra complete as per manufacturers specifications or instruction of Engineer In charge

Fixing of PVC nozzle complete after drilling at field welded/shock welded joints in the MS Plate and fixing nozzle with epoxy mortar/high strength repair mortar as per as per manufacturers specifications or instruction of Engineer Incharge

Injection of polymer cement slurry by electrically driven pump/manual operated pump with defined pressure and maintaining consistent slurry of Polymer(KUNACRETE) and Cement (OPC 43 Grade),admixed with Non shrink grouting polymeric cement(KUNABEX-100) as per manufacturers specifications or instruction of Engineer Incharge,allowing injected material to get cured for optimum technical properties.

Injection of Micro Fine Cement (KUNA MFC) with required water/powder ratio by electrically or manually operated injection pumps admixed with KUNA –ANTI Freeze admixture in defined proportions as per manufacturer’s specifications or instruction of Engineer Incharge, allowing it to get cured for optimum technical properties

Removal of nozzle for redrilling and fixing of Non Returned valve (NRV) packers of required size and fixing it in position as per manufacturers specifications or instruction of Engineer Incharge

njection of Flexible single component Polyurethane Foam (KUNA PUR Inject 1C Flex) and semi rigid Single component polyurethane foam (KUNA Pur Inject 1C Hydrofoam) by electrically driven pump with defined pressure complete as per manufacturers specifications or instruction of Engineer Incharge.

Removal of Packers

Application of Polyurea Primer over the prepared, dried and injected surface (KUNA UREA Prime) as per manufacturers’ specifications or instruction of Engineer Incharge

Application of Pure spray applied Pure, flexible Polyurea over the cured primer in 2-3 mm thickness as a seamless, flexible water proofing membrane over the steel surface with hot spray plural pump (GRACKO reactor or equivalent only) as per manufacturers specifications or instruction of Engineer Incharge.

NOW Methodology for cracks which have already developed in existing tracks-Using Injection packer system by applying 2 component Low viscosity epoxy injection grout sealing the cracks and increasing strength further

Cracks /Surface should be properly cleaned using mechanical means to make it free from any foreign particle-dust, grease and others.
Drilling and fixing of NRV packers of required sizes and at required distances
KUNAGROUT -2 EP (Low viscosity two component injection grout is formulated by mixing in ratio 2:1 and is pumped with injection grouting machines. It has got extremely high strength/low viscosity, tremendous penetration and excellent bonding properties. Allowing the system to get cured.

Index of various construction chemicals used by KCPL in the study

KUNAPLAST PC-100 (High range water reducing PC base hyper plasticizers) for producing excellent quality M-35 grade concrete for APRON
KUNAPOXY GROUT-3EP – 3 component thixotropic self leveling epoxy grout systems for anchorage bolts during laying of track
KUNABOND-SBR: SBR latex based bonding agent to bond old and new concrete during intermittent pours of concrete
KUNAFIX-80 (Polyurea base construction joint sealant)-Sealing various construction joints .Absolutely must for sensitive structures like track
KUNAGROUT-GP (General purpose non –shrinkage cementitious grout for pockets and foundations
KUNAPOXY-ZN: Zinc rich polyamide base epoxy coating for anti corrosion property of rails
KUNAGROUT-2EP (Low viscosity epoxy injection grout)-For sealing cracks which have already developed in existing track structure.This is through injection methodology

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