Common Concrete Defects- Training Presentation Draft
Transcript of Common Concrete Defects- Training Presentation Draft
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COMMON CONCRETE
DEFECTS & REMEDIES
Quality Awareness Training-02
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Concrete defects, what are the issues?
Reasons for their development of Concrete defects
may be.
Poor Materials
Poor Construction Practice/Construction faults Bug holes/Pinholes
Honeycombing
Exposed Reinforcing steel / Concrete Cover
Cold joints
Irregular surface
Popouts /Bulges
Poor Supervision or a Combination
Surface Cracks (shrinkage/Plastic before hardening)
Dimensional Deviations
Chip off and Damages
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Poor Construction Practice/Construction
faults Bug holes/Pinholes
Picture Bad Picture Good
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Poor Construction Practice/ Construction
faults Cement Slurry Leakages
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Poor Construction Practice/ Construction
faults Honeycombing
Picture Bad Picture Good
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Poor Construction Practice/Construction
faults Rebar exposed & Concrete Cover
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Poor Construction Practice/Construction
faults Cold Joints
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Poor Construction Practice/Construction
faults Top Surface Finish and Defects
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Perfect Repair of Pinhole/Bug Holes
Cosmetics Repairing Materials & Tools
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Perfect Repair of Pinhole/Bug HolesCosmetics Repairing MaterialsSample Finish
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Possible Causes Poor Concrete compaction due to ineffective vibration or
Rebar congestion. Concrete slurry leakage along the perimeter side forms due
to:
*Loose or missing supports /fixing bolts
* Damaged Rubber gasket seal.
* Defective formwork/Mould
Inadequate concrete vibrator and negligence to vibrate
Less concrete cover and spacing between the reinforcement
Inadequate supervision and no hammering the side surface to
remove the voids/Bubbles .
Remedial Measures Honeycombing and pin holes must be rectified immediate
after stripping of sides with approved repairing Material.
Excessive Honeycombing & loose partials must be cleaned
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Vibration
Picture Bad Picture Good
Proper Vibration will avoid the Honey Comb, Pin hole Defects
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Formwork / Mould
Picture Bad Picture Good
Proper form Work / Mould will avoid the Concrete Slurry Defects
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Concrete Cover Spacing
Picture Bad Picture Good
Proper Covering Block will avoid the Rebar Exposed Defects and Design
Failure
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Damages occurring mainly due to Inadequate
Supervision & Negligence.
Supervision or a Combination
Dimensional Deviations, Chip off & Damages
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Supervision or a Combination
Dimensional & Formwork Deviations
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Possible Causes Mould of forms may not be sufficiently rigid to maintain
specified tolerance during concrete pouring Precast elements may not have gained sufficient concrete
strength when demoulded.
Train Operators and Riggers for Safe Lifting Operation
Top surface finish of precast elements may not be properly
leveled and troweled during production which result in
different levels & surface undulation.
Remedial Measures For minor deviation, corrective measures such as surface
grinding. Trimming/hacking and skim coat application can be
appropriately used to remedy the situation. Strictly follow the approved Method Statement .
Stripping and Lifting strictly follow the Cube results.
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Supervision or a Combination
Surface Cracks
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Supervision or a Combination
Surface Cracks
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Possible Causes Lifting and Stripping of Precast units before concrete mature
Cracks may have accrued during initial lifting due to friction
between the elements and casting Mould forms.
Inadequate supervision & Improper curing method; curing
time &temperature variations leads cracks on the surface
Uncontrolled concrete mix and Negligence while pumping
concrete, such as excess water and excess floating Inadequate handling Techniques
Insufficient lifting points; No appropriate tools & method
while lifting precast units.
Type of CracksA. Before Hardening: B. After Hardening:
Early frost damage Physical reactivity
Plastic Chemical reactivity
Construction Movement Thermal contraction/reactivity
Structural impact/Design loads
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Remedial Measures & Acceptance Tolerance
All the cracks should be examined by a qualified engineer to
determine the Types & Acceptance.
Depends on the location and seriousness of the cracks,
different repairs method can be used to correct the cracks.
Proper curing system and covering with Polythene sheets
must be improved for the fresh concrete to control Early
frost damage& Plastic cracks Surface cracks and Hairline cracks (not more than 0.3mm
width) can be repaired by cutting a V groove of specified
minimum depth along the crack lines, followed by patching.
Material used for the cracks repairGravity flow material, Injunction based Epoxy,
PVA based polymer grout, Cementations grout , etc.
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Test Paper
1. Which will avoid the Honey Comb, Pin hole Defects ?
a. Leveling b. Vibrator c. Shuttering oil2. Which will avoid the Concrete Slurry Defects ?
a. Proper Form Work b. Steel Work c. Cover Block
3. Which will avoid the Rebar Exposed Defects and Design Failure ?
a. Block Work b. Cover Block c. Form Work
4. What are the damages occurred due to Inadequate Supervision?
a. Dimensional deviation b. Pin hole c. Honey Comb
5. What type of crack Observed Before Hardening ?
a. Physical reactivity b. Chemical reactivity c. Construction
Movement
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Thank you