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SEMINAR ON

SEMINAR ON. BY naser ur rahman 3gn09cv024. UNDERWATER CONCRETING. Topics covered. Introduction Concrete specification Laying techniques Repair works Conclusion. Introduction.

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SEMINAR ON

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  1. SEMINARON BY naserurrahman 3gn09cv024 UNDERWATER CONCRETING

  2. Topics covered • Introduction • Concrete specification • Laying techniques • Repair works • Conclusion

  3. Introduction There are often situations such as basements , sewerage ,ducts , harbours , bridges and marine works ,in which concrete is to be placed underwater. Special precaution need to be taken whenever the concrete is to be placed underwater. The concrete should be plastic and cohesive but should have good flowability.

  4. Performance requirements for UWC • Workability & self compaction • Cohesion against washout, segregation & laitance formation • Low bleeding • Low heat of hydration • Controlled set time • Compressive strength • Adequate bond • Problems faced • Segregation of fine aggregates from coarse aggregates • Water pollution • Increased w/c ratio • washout

  5. Types of Materials used : • Cement • Coarse Aggregates • Fine Aggregates • Admixtures

  6. CEMENT : Types of cements used in UNDERWATER CONCRETING : • Ordinary Portland Cement (OPC) • Sulphate Resisting -Portland Cement ( SRPC ) • Low Heat - Portland Cement ( LHPC )

  7. AGGREGATES : • Coarse Aggregates : The coarse aggregate for intruded in concrete shall conform to the following gradation: • Maximum Size - 1.5-2 inch (100% shall pass a 75 mm sieve ) • Minimum Size - material passing a 19 mm sieve shall not exceed 5% by mass of the coarse aggregate.

  8. Fine Aggregates : • The sand for the intruded grout shall be well graded, preferably of round grains and shall conform to the following gradation: • Passing 1.18 mm sieve 95 - 100% • Passing 600 um sieve 60 - 85% • Passing 300 um sieve 20 - 45% • Passing 150 um sieve 15 - 30% • Passing 75 um sieve 0 - 10%

  9. Use of Different Admixtures • Anti-washout admixtures • Hydrocem • Mellose • Rheomac uw-450 • Viscosity modified admixtures • Naphthalene Formaldehyde • Sulfonated Melamine Formaldehyde

  10. Concrete Particles with adding MELLOSEConcrete Particles without MELLOSE

  11. Concrete laying techniques • Placing in Bags • Tremie method • Bucket placing • Prepacked concrete

  12. Tremie method

  13. Use of Tremie Method

  14. Divers Using Tremie Concreting

  15. Bucket placing

  16. Prepacked concrete

  17. Repair works • Defining the Area • Cleaning the Affected Area • Equipment Haulage • Use AWA • Personnel requirements • Inspection methods • Environment considerations

  18. An Inspection Machine

  19. References: • www.ce.berbley.edu/~parmont/165/tremie • www.vulcanhammer.net • www.ce.gatech.edu/~kk92/classpress/uwater/index.htm • www.scanecm.com.au/products/additives/hydrocem/index.htm • www.ce.ecn.purdue.edu/cem/cliproj/civil/mellose.htm • www.masterbuilder.com/uc.htm • Concrete Technology - M L Gambhir • Concrete Technology - A R Santhakumar

  20. Thank you

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