SEMINAR ON
description
Transcript of SEMINAR ON
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SEMINARSEMINARON ON
BY naser ur
rahman 3gn09cv024
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Topics coveredTopics covered
Introduction Concrete specificationLaying techniquesRepair worksConclusion
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Introduction 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.
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Performance requirements for UWCWorkability & self compactionCohesion against washout, segregation & laitance
formation Low bleedingLow heat of hydrationControlled set timeCompressive strengthAdequate bond
Problems facedSegregation of fine aggregates from coarse aggregatesWater pollutionIncreased w/c ratiowashout
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Types of Materials Types of Materials used used ::
Cement Coarse Aggregates Fine Aggregates Admixtures
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CEMENT :CEMENT : Types of cements used in UNDERWATER
CONCRETING :
Ordinary Portland Cement (OPC)
Sulphate Resisting -Portland Cement ( SRPC )
Low Heat - Portland Cement ( LHPC )
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AGGREGATES 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.
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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%
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Use of Different Use of Different AdmixturesAdmixtures
Anti-washout admixturesHydrocem Mellose Rheomac uw-450
Viscosity modified admixturesNaphthalene FormaldehydeSulfonated Melamine Formaldehyde
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Concrete Particles with adding MELLOSE
Concrete Particles without MELLOSE
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Concrete laying Concrete laying techniquestechniquesPlacing in Bags
Tremie method
Bucket placing
Prepacked concrete
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Tremie methodTremie method
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Use of Tremie Method
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Divers Using Tremie Concreting
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Bucket placingBucket placing
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Prepacked concretePrepacked concrete
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Repair worksRepair works
Defining the AreaCleaning the Affected AreaEquipment HaulageUse AWAPersonnel requirementsInspection methodsEnvironment considerations
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An Inspection Machine
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ReferencesReferences::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
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