Structural Retrofitting Process and Techniques Md. Mostafizur Rahman Sr. Business Consultant Fosroc Chemicals (I) Pvt Ltd
Brief over view of FOSROC Construction Products Supplier with Manufacturing facilities in 30 countries and export to another 100 countries. Product Ranges Admixture Protective coating Surface treatments Grouts Waterproofing Joint Sealant Structural Repair and strengthening Concrete Adhesives Flooring Grinding Aids (Plasticisers- Ligno Sulphonates, Super Plasticisers- SNF and SMF and Hypersuper Plasticisers- PCE) Conplast and Structuro series. Epoxy, epoxy tar, polyurethane Polymer coating, epoxy tar, was based surface treatments coating. Cementitious (Conbextra GPI, GP2, HR etc.) ; Epoxy Grout. Proofex Engage, Loose laid Membranes, self adhesive and Polymer coating membrane. Polyurethane, Polysulphide, acrylic, epoxy modified FRP (Carbon, Glass); Repair Mortar, Micro Concrete Epoxy, SBR and Acrylic bonding agent including tiles adhesives Epoxy, polyurethane and Cementitous. Cement performance enhancer.
Steps for Structural Retrofitting Diagnosis of existing structure through NDT and DT and identify deficiencies through analysis of structures. Design of structural retrofitting scheme following standard codes of practices Execution of retrofitting work from reputed contracting house
Distress of Concrete owing to Fire
Distress of Concrete (Two-way ribbed Slab)- Fire Burnt
Distress owing to corrosion
Strengthening owing to corrosion
Strengthening owing to corrosion
Section Enlargement owing Under design
Section enlargement owing to U/D
Restoration of Concrete CONSTRAINTS: Most of the cases, as-built drawing is not readily available Sub structural drawing and Soil test reports are not available Concrete of columns is often inferior than floor slab Stressed structure to be retrofitted with the existing loading pattern
Restoration Methodology METHODOLOGY : Surface Preparation: Chipping off the loosely adhered damaged and carbonated concrete, Step-II Repairs with micro concrete: a) Application of anti corrosive epoxy zinccoating (Nito Zinc Primer) to re-bars. b) Anchoring Shear Connectors and Main bars using polyester resin anchor grout LOKFIX P. c) Epoxy Bonding agent (Nitobond EP) in between parent and new micro concrete. d) Core cutting on the top of the slab to facilitate pouring of Free flow Micro Concrete (Renderoc RG) for Slab/ Micro Concrete Encasement for columns/ Beams.
Step-1: Surface preparation and Fixing additional Rebar by LOKFIX Anchoring adhesives
Step-2 :Nitozinc Primer; Anti corrosion coating in case of corroded and fire damaged structure
Step-3 Bonding agent in between parent and Micro concrete
Step-4: Fixing form work and Micro Concrete encasement
Slab retrofitting: Concrete core cutting of Slab, bonding agent application and pouring micro concrete
Pouring of Micro Concrete; Renderoc RG; W/P: 0.16, Grade: M50
Pouring of micro Concrete and restoration
Pouring Micro Concrete and Restoration
Cabon Laminates (Nitowrap CFP 50) Installation
CFRP Plate installation; Nitowrap CFP 50: 1.2 mm x 50 mm x 100 M
Carbon Fiber Wrapping to Column bean joint
Carbon Fiber ; Nitowrap EP (CF)
Joist Installation and GAP filling in between Joist and slab
Basement and Footing Load bearing capacity increment- Installation of Temporary Support
Basement Thickness Increment
Footing size increment
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