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Mohd Zahri Seman

Bahagian Forensik (Struktur dan Jambatan)Cawangan Kejuruteraan Awam, Struktur dan Jambatan (CKASJ)

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PEMBAIKAN / PEMULIHAN

Untuk memulihkan sebahagianatau keseluruhan struktur yangrosak kepada tahap khidmatrekabentuk dan untukmeningkatkan ketahanlasakan.

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PENGUKUHAN(STRENGTHENING)

Untuk menaik taraf struktur

kepada tahap khidmatrekabentuk yang lebih tinggimeningkatkan keupayaan

menanggung beban.

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PROSES PEMBAIKAN

DetailedInvestigation

VisualInspection

DefectMapping

NonDestructive

Test

StructuralAnalysis

DiagnoseCause(s) of

Defects

Durabilityproblem

Structuralproblem

SelectRepairMethod

Good Knowledge in Material Products andRepair Methods

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JENIS KEROSAKAN

Keretakan disebabkan olehpergerakan hakiki

pengecutan(shrinkage)

rayapan (creep)

penghidratan (hydration) perubahan suhu

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JENIS KEROSAKAN

Kemerosotan Bahan

serangan asid

serangan sulfate

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JENIS KEROSAKAN

Keretakan disebabkan oleh kerosakanstruktur

penambahan beban kekurangan dalam rekabentuk &

spesifikasi

mutu kerja yang tidak baik

pergerakan pada asas struktur

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KEPERLUAN BAHAN

Mesti mempunyai kebolehkerjaan yangbaik

Honeycomb

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KEPERLUAN BAHAN

Rintangan yang baik terhadap ejen agresif

Pengkarbonatan pengaratan tetulang

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KEPERLUAN BAHAN

Rintangan yang baik terhadap ejen agresif

Serangan Kloridapengaratan tetulang

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KEPERLUAN BAHAN

Ikatan yang baik / pengecutan terpampas

Delamination / keretakan

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PELBAGAI BAHAN PEMBAIKAN

Prestasi Keperluan Bahan Pembaikan

Ikatan yang baik untuk substrat konkrit

bersifat rencam (compositely)

Kekuatan

Sekurang-kurangnya kekuatanseperti konkrit yang sedia ada

Pengecutan yang rendahMengurangkan tekanan dalaman dankeretakan

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Repair Materials The Choice

Cementitious material

Most widely used

Very close mechanical properties to thestructure

Relatively cheaper Resin mortars

Very rapid high strength development

Higher resistance to physical attack such as

high impact or abrasion Provide less permeable cover

Higher resistance to chemically aggressiveenvironment

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Cement-Based Mortar or Concrete

Wide availability and low cost

Cement mortars for small repair and

concrete for large repairPortland cement high early strength or

sulfate resistant

Appropriate admixtures impact improvedqualities

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Epoxy Mortars

Excellent bond properties

High strength and rapid strengthdevelopment

Fast cureExcellent chemical resistance

Insensitivity to moisture or a wetenvironment

High resistance to impact and abrasion

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Application for Epoxy Products

Pressure grouting

Low-viscosity resins to fill fine cracks

Concrete repair

An epoxy resin is mixed with filler

aggregates

Providing doweling action

Repair of deck joints and concrete

surfacesHigh resilience and strength under bearing

pads

Adhesion between fresh and old concrete

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Cement-Based Polymer Concrete

Polymer mixed with a cement-basedmortar

Emulsion

small, spherical plastic particles,disperses throughout the cement paste

Concrete mix are blocked

Reducing permeability and shrinkage

and improving chemical resistance,flexural strength, adhesion andresistance to abrasion

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Superfluid Microconcrete

Specialist formulator product

High strength, polymer modified, free flowingcementitious material

Pre-packed

Factory controlled quality

Main used Formwork repair

Fluid cement grouts mixed with small aggregate(10mm)

Contain no metallic expansion systemSelf compacting

Shrinkage compensated in both liquid andcured states

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KAEDAHPEMBAIKAN

Crack repair

Patching repair / handplaced

Formwork repair

Sprayed Concrete

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Crack repair methods

Non-structure cracks Wide crack- sealed with epoxy resin /

cementitious grout injection(>0.25mm)

Fine crack- sealed with epoxy resin

(

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Crack repair methods

Crackwidth

CrackWidth

RepairMethod

5mm Method 3

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Crack repair methods

This repair method is not applicable to the cracks

caused by corrosion of the reinforcement.

Repair Method is applicable for passive cracks

(inactive cracks) only.

All concrete cracks shall be under dry condition

(strictly no damp/wet condition/ standing water) in

order to allow the repair material to bond properly.

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Crack repair methods

METHOD 1

CRACK WIDTH LESS THAN 0.25mm

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Crack repair methods

METHOD 2

CRACK WIDTH FROM 0.25mm UP TO 5.0mm

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Crack repair methods

METHOD 3

CRACK WIDTH MORE THAN 5.0mm

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CRACK INJECTION

Apply to repair cracks by injection epoxy groutinto the cracks to locked the concrete

General Work Procedure

1. Surface treatment of crack

2. Seal crack surface and markinjection pipes

3. Fit injection pipes

4. Commence injection work

5. Final surface treatment

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Epoxy Injection Work Sequence

1. Mark crack locations andremove any loose materialwith wire brush.Oil and grease should

be clean with a piece ofCloth dipped into thinner.

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Epoxy Injection Work Sequence

2. Attach fitting pipesat Injection points.

* spacing between injection points differwith crack width

Spacing between injection points

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Spacing between injection pointsdiffer with crack width

Crack Width (mm) Injection Pipe Interval (mm)< 0.3 50 - 100

0.3 0.5 100 - 200

0.5 1.0 150 - 250

> 1.0 200 - 300

Injection pipeInterval

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Epoxy Injection Work Sequence

3. Seal crack surface to a thickness ofabout 3mm and width of 50mm and cureuntil it harden.

4. Screw in the INJECTION intothe fitting pipes

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Epoxy Injection Work Sequence

5. Pour the mixed grout into the pump andcommence injection work after fixingpump hose to the injection pipe.

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Epoxy Injection Work Sequence

6. Cure the injection material until it hashardened.

7. Remove the fitting pipe by hammering it

off.

8. Finish the repaired areas to a flat surfaceusing disc grinded.

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Concrete Repair Process

Removal of defective concrete Reinforcement preparation

Removal of corrosion products

Lap new reinforcement

Priming

Place repair material

Patch repair

Formwork repair

Guniting

Prepacked grouting

Protective coating

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Removal of Defective Concrete

Mark areas to be removedSaw cut edges of repair area by 10 mm

20 mm deep

Concrete removal by jack hammers or

waterjet

Removal must not damage rebar

Removal must be 20mm behind rebars

Remove contaminated concrete Provide access for cleaning corrosion

Removal additional 50mm beyondcorroded rebar

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Removal of Defective Concrete

Clean remaining concrete surface High pressure air

High pressure water jet

Removal only on alternate columns /beams within same span

No imposed load directly above

f

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Reinforcement Preparation

Remove all corrosion products Wire brush

Sand/grit blasting

Rebar corrosion more than 10% has to besupplemented

Minimum lap length = 42 Dia

Prime rebar within 2 hours of cleaning

using zinc-rich type primer

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A li i C i i f P hi

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Application Criteria for Patching

Inactive defects due to honeycomb,spalling, cavity etc.

Spalling/ defective area not more than0.5m2

Localised / small defect

Causes

Poor workmanship

Minimal carbonation Inadequate cover

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Concrete Patch Repair

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Concrete Patch Repair

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Concrete Patch Repair

LAPPING FOR NEW REINFORCEMENT

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Concrete Patch Repair

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Patch Repair Work Sequence

1. Mark out repair area

* Define defective location

P t h R i W k S

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Patch Repair Work Sequence

2. Break out concrete using jackhammer or other mechanicalmeans* Remove behind corroded

steel

3. Saw cut edges of repair zone* No feather edges

h k

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Patch Repair Work Sequence

4. Clean corrosion productsby grit blasting or wirebrushing

Patch Repair Work Sequence

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Patch Repair Work Sequence

5. Prime reinforcement within

2 hours of preparationusing zinc-rich type primer

Patch Repair Work Sequence

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Patch Repair Work Sequence

6. Wet substrate with clean

water

7. Apply a thin layer of bondingagent

Patch Repair Work Sequence

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Patch Repair Work Sequence

8. Hand applied repair mortarin layers of about 10 mm each

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P t h R i W k S

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Patch Repair Work Sequence

10. Make good the finish surface

using a trowel or sponge

11. Cure immediately to the

entire repair area

Application Criteria for Formwork

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ppRepair

Cracks / delaminations / spalling resultingform corrosion of rebar

Chloride ingress and carbonation

Adraded concrete surface with loss ofcement matrix

Material deterioration due to sulfate oracid attack

Large repair area

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F k R i

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Formwork Repair

Fo m o k Repai

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Formwork Repair

Formwork Repair

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Formwork Repair

Formwork Repair

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Formwork Repair

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Formwork Repair

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Formwork Repair

Formwork Repair

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Work Sequence

1. Remove defective and

unsound concrete to 20 mm

behind reinforcement

Formwork Repair

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Work Sequence

2. Clean corrosion products

by grit blasting or wire

brushing

Formwork Repair

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Work Sequence

3. Prime reinforcement within

2 hours of preparation using

zinc-rich type primer

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Formwork Repair

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Work Sequence

5. Mix grout high strength, polymermodified,

prepackaged free flowing cementitiousmaterial superfluid microconcretes

Formwork Repair

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Work Sequence

6. Place superfluid

microconcrete into formwork

* ensure that grout fully

filled the funnel to avoidair entrapment

Formwork Repair

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Work Sequence

6. Reinstated column

Sprayed Concrete

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Sprayed Concrete

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Sprayed Concrete

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p y

Sprayed ConcreteW k S

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Work Sequence

1. Existing concrete surface need to beroughened to a profile necessary toachieve mechanical interlock

Sprayed ConcreteW k S

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Work Sequence

2. Sprayed concrete (wet process)

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Sprayed ConcreteW k S

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Work Sequence

4. Apply skim coating to the entire repairarea

Sprayed ConcreteW k S

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Work Sequence

5. Final output

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TERIMA KASIH