Fibre Wrapping System for Structural Strengthening

• Strengthening undersigned RCC Prestressed concrete structures subjected to axial loads, bending or both. Typical are - strengthening the piers of bridges which are to receive higher loading due to heavier traffic or due to lane widening ( or superstructure widening without changing the piers) • For strengthening the existing T beam bridge superstructure. In this case the flexural and shear capacity of T beams can be increased. • Strengthening of slab beam or flat slab structures by adopting composite system by providing additional concrete topping on existing slab and fiber reinforcement from underside of slab and beam. About 30% improvement in structural capacity is possible. • Strengthening existing RCC corrosion damaged structures like columns, beams, silos, water tanks, process vessels (in RCC in Industrial plants). The strengthening would itself provide protection from further attack. It can be done with minimum shutdown and consequentially less downtime cost. Silos and water tanks can be put to reuse within a week or 10 days, since the strengthening system cures within 24 hours. • Tall chimney structures can be strengthened for enhanced performance under changed earthquake conditions. • Strengthening of existing inadequately designed RCC structures, due to some constructional errors. Placing conventional reinforcement into a constructed structure is very difficult. The surface applied wrap takes care of these deficiencies within the limit to which concrete can take stresses. • Strengthening of circular RCC structure where hoop stresses are predominant. The wrapping works with full efficiency since the predominant force to be resisted is uni-directional tension (hoop)

• Old Masonry structures such as monuments, temples, churches etc. can be strengthened using fiber wrapping. Here the confinement offered by wrapping increases the integrity of masonry ( which in fact is in question in case of old structures). Wrapping can improve stability of the masonry domes also.
Advantages of Fiber Reinforcement• Ease of Application
• High strength to weight ratio
• Corrosion resistance
• Resistance to environmental degradation
• Tailorability
• Low installation time (i.e. less downtime)
• Can be installed in areas with limited access
• Less thickness than the conventional strengthening
• Create a barrier to moisture ingress

Methodology Of Wrapping

1. ) Surface grinding to get an even surface, all projections to be grounded off. Grind sharp corners to 25 mm radius. This is to avoid stress concentration.	5.) Take precut FRP sheet, orient properly as per design consideration. Place on saturant and press by rollers to squeeze out the saturant through the fabric. Air bubbles are also removed due to this operation.
2.) Apply Primer to the prepared concrete surface.	6.) Apply second coat of saturant to saturate the fabric fully. For subsequent wrap layers follows the same set of steps except the surface preparation, primer and putty. If any disbonded fabric or air entrapment found then cut open and apply new patch of fabric after putty filling.
3.) Apply Putty on concave areas. The concavity can lead to air trapping inside and lack of full contact.	7.) Apply a suitable bonding coat before plastering.
4.) Apply first coat of saturant by roller or brush.	8.) Plaster the entire surface