Repair_and_maintenance_of_RCC_structure.pptx

Repair and maintenance of RC Structure

1. Protection repair and maintenance of rcc structures

2. Concrete expected to give trouble free service throughout design life. Concrete decay is cancerous caused by carcinogenic agents. Physical damage caused due to fire,explosion and restraints both external and internal. introduction

3. Lack of maintenance has resulted in near loss of this irrigation structure.

4. Seal the surface of the concrete Modify the concrete to reduce its permeability Protect the reinforcing bars to reduce the effect of chlorides PREVENTION OF CORROSION IN REINFORCEMENT

5. Good concrete practice Latex modified concrete Silica fume concrete Epoxy coated reinforcement Providing membranes and sealers Cathodic protection Electro osmosis Inorganic corrosion inhibitors Organic corrosion inhibitors Corrosion controlling steps

6. Specify and introduce Chloride limit Maintain a low water-cement ratio in concrete Provide adequate cover to the reinforcing steel Provide adequate curing Use of water-reducing admixtures Consolidating the concrete thoroughly Use post tensioning Include provision for immediate repair of cracks Good Concrete Practice

7. Latex modified concrete is prepared by adding liquid styrene butadiene latex to conventional concrete Latex modified concrete should be placed in the evening or at night to reduce cracking Use of Latex Modified Concrete

8. Silica fume reacts with calcium hydroxide to form additional cementitious material Silica fume is extremely puzzolonic material that reacts with calcium hydroxide Performance of concrete is good to excellent Use of Silica Fume Concrete

9. Pre-cleaned reinforcing steel bars are protected with a coating of powdered epoxy Coating blocks chloride ions Performance is poor to excellent Epoxy Coated Reinforcing Bars

10. Post curing heating enclosure installed over an epoxy mortar repair area

11. A bucket mixer can be used to mix epoxy mortar for small repair areas.

12. Membranes and sealers help prevent chloride entry Urethanes, neoprene, or epoxies are usually used to built up in multiple layers of membranes The performances of these materials vary depending upon the base of the sealer Sealers- linseed oil and sophisticated silanes and siloxanes Use of Membranes and Sealers

13. controls corrosion of steel by applying direct current is a complicated process that requires extensive pre installation and monitoring Corrosion of steel in concrete is a electrochemical process Steel (reinforcement) inside the concrete act as cathode and provide protection Concrete act as anode Not recommended for carbonated concrete Cathodic Protection

14. Electro Osmosis makes it possible to restore the initial alkalinity of the concrete externally applied alkaline gel covering the external conductor is drawn alkalinity increase of a carbonated concrete restores the passivation The carbonate problem is solved Electro Osmosis

15. combine other organic chemicals for successfully inhibiting corrosion inhibitor forms a protective barrier on the reinforcing steel barrier prevents reaction between the iron and chloride Organic Corrosion Inhibitors

16. . Experience has shown that there are certain portions of exposed concrete structures more vulnerable than others to deterioration from weathering in freezing climates Concrete sealing compounds and coatings that provide good protection from weathering REPAIR AND MAINTENANCE OF CONCRETE

17. Determine the cause(s) of damage Evaluate the extent of damage Evaluate the need to repair Select the repair method Prepare the old concrete for repair Apply the repair method Cure the repair properly Reclamation’s concret e repair system

18. Surface Grinding Using Portland Cement Mortar Dry Pack and Epoxy-Bonded Dry Pack Preplaced Aggregate Concrete Replacement Concrete Epoxy-Bonded Epoxy Mortar Polymer Concrete Silica Fume Concrete Methods of concrete repair

19. It can be used to repair some bulges, offsets and other irregularities. Grinding of sufaces subjected to cavitation erosion should be limited in depth so that no aggregate particles more than 1/16 th inch in cross section are exposed to finished surface. Grinding of surfaces exposed to public view should be limited in depth so that no aggregate particles more than 1/4 inch in cross section are exposed at the finished surface Surface grinding

20. Dry pack is a combination of Portland cement and sand passing a No. 16 sieve Dry pack should be used for filling holes having a depth equal to, or greater than, the least surface dimension of the repair area; for cone bolt, she bolt etc. Dry Pack and Epoxy-Bonded Dry Pack

21. Preplaced aggregate concrete is made by injecting portland cement grout, with or without sand, into the voids of a formed, compacted mass of clean, graded, coarse aggregate The preplaced aggregated is washed and screened to remove fines before placing into the forms Preplaced Aggregate Concrete

22. Concrete repairs made by bonding new concrete to repair areas without use of an epoxy bonding agent or mortar grout applied on the prepared surface should be made when the area exceeds 1 square foot and has a depth greater than 6 inches. Replacement concrete repairs are made by bonding new concrete to the repair areas without the use of a bonding agent or Portland cement grout Replacement Concrete

23. Portland cement mortar may be used for repairing defects on surfaces not prominently exposed Repairs may be made either by use of shotcrete or by hand application methods Portland Cement Mortar

24. Epoxybonded epoxy mortar should be used where the depth of repair is less than 1-1/2 inches and the exposure conditions are such that relatively constant temperatures can be expected Epoxy mortars have thermal coefficients of expansion that may be significantly different from conventional concrete Epoxy-Bonded Epoxy Mortar

25. epoxy injection equipment

26. difference in potential can result in the formation of a galvanic corrosion cell with accelerated corrosion at the repair perimeters The epoxy bond coat and epoxy mortar create zones of electrical potential that are different from the electrical potential in the surrounding concrete

27. Polymer concrete (PC) is a concrete system composed of a polymeric resin binder and fine and coarse aggregate Water is not used to mix polymer concrete PC is commonly used to repair potholes in concrete highway bridge decks, thereby eliminating the necessity of long and costly road closures or detours the monomer molecules are chemically linked and cross linked to form a hard, glassy plastic known as a polymer. Polymer Concrete

28. Placing polymer concrete in a repair area

29. Silica fume concrete is conventional portland cement concrete containing admixtures of silica fume Silica fume is a finely divided powder byproduct resulting from the use of electric arc furnaces Silica Fume Concrete

30. a small silica fume concrete repair

31. Repair and prepared corrected area should be carried out systematically application of protective coatings are required to be properly supervised and carried out. Surface defects like bugs holes and honey comb require immediate repairs CONCLUSION

32. THANK YOU……..