concrete structure repair - ridresearch.rid.go.th/rte/attachments/article/72/3.concrete... · 2019....
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Concrete Structure RepairConcrete Structure Repair
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Dept. of Civil Engineering, Kasetsart University
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Purpose of Repair
• Control development of deterioration of structures
• Recover their durability• Mitigate negative impact against the pac aga s ethird parties
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Crack repair methods Surface covering methodCrack repair methods Surface covering method
Injection method
Section repair methods Filling method
Surface coating repair methods exfoliate [VI] ลอกออก
Syn delaminate; desquamateRepair methods Electro‐chemical repair
methods
Syn. delaminate; desquamateRelated. หลดออกเปนแผน, ตกสะเกด
methods
Electro‐anti‐corrosion th d
Desalination method
Re‐alkalization methodmethod
Others
Re‐alkalization method
Impregnation methodOthers
Prevention method against exfoliation
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วสดทคณภาพด (Sound Materials)
การเตรยมการทด(Thorough Preparation)
การดาเนนงานทเหมาสม(Proper Application)
นามาซง
การซอมแซมทนาพงพอใจ(A Satisfactory Repair)
โดยมปจจยเหลานอยางพอเพยงโดยมปจจยเหลานอยางพอเพยง
กาลง (Strength)
ความคงทน (Durability)
ลกษณะภายนอก (Appearance)
ประหยด (Economy)
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สาเหต ประเภทของรอยราว ขอแนะนาActive Dormant
นาหนกบรรทกทเกดจากอบตเหต xนาหนกบรรทกทเกดจากอบตเหต xความผดพลาดจากการออกแบบ (เหลกเสรมไมเพยงพอ) x ควรมการกาหนดนาหนกบรรทกทรบไดหรออาจ
ตองมการออกแบบใหมและมการซอมแซมหลงจากการออกแบบใหมหลงจากการออกแบบใหม
ความเคนเนองจากอณหภม x อาจจาเปนตองแกไขการออกแบบรวมไปถงการเพมรอยตอเพอการขยายตว
การเกดสนมของเหลกเสรม x การซอมรอยราวอยางเ ดยวอาจไม เ พยงพอการเกดสนมของเหลกเสรม x การซอมรอยราวอยางเดยวอาจไมเพยงพอเนองจากสนมยงคงเกดขนตอเนองและอาจทาใหเกดรอยราวเพม
การทรดตวของฐานราก x x ควรมการวดและตรวจสอบวาการทรดตวของฐานการทรดตวของฐานราก x x ควรมการวดและตรวจสอบวาการทรดตวของฐานรากยงมอยางตอเนองหรอไม
ปฏกรยาระหวางมวลรวมกบดาง x การซอมรอยแตกราวอยางเดยวอาจจะไมเพยงพอเนองจากหากยงมความชน คอนกรตกยงคงเนองจากหากยงมความชน คอนกรตกยงคงเสอมสภาพอยางตอเนอง
กระบวนการกอสรางทไมไดมาตรฐาน (บมคอนกรตไม ไ
xเพยงพอ ไมแบบเคลอนตว เปนตน)ความผดพลาดจากการออกแบบเชน การเชอมวสดทมคาการขยายตวทแตกตางกนมากๆ ซงอาจทาใหเกดความเขมของหนวย
ไป
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แรงทมากเกนไป (Stress concentration) และระบบรอยตอโครงสรางทไมถกตอง (Faulty joint systems) ได
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Repair Method for Cracks• Purpose of crack repair
Improve water permeability– Improve water permeability– Enhance durability of concrete
• Methods• Methods– Surface paint type– Injection type– Injection type– Filling type
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Surface Paint Type
Dept. of Civil Engineering, Kasetsart University
Surface Paint Type
I j i TInjection Type• Injection materials
– Epoxy resinEpoxy resin– Acryl resin– Cement type– Polymer‐cement type
• Core‐boring test or Non‐destructive methoddestructive method
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Filling TypeDept. of Civil Engineering, Kasetsart University
Filling Type
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Dept. of Civil Engineering, Kasetsart University
• Wire anchor method• High tension wire anchor methodHigh tension wire anchor method
Anchor
Drilling should be carried out by drill, and cement mortar, synthetic resin mortar should be packed.
Prestressing Steel Bar
Example attached outside member
Example attached inside member by drilling (Anchorage portion can be embeded in member.)
There is also a method to embed the steel bars inside concrete.
Crack
p
Prestressing Steel Bar
Space around prestressing steel bar should be grouted.
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Cross Section Repair
Dept. of Civil Engineering, Kasetsart University
Reinforcing BarCross Section Repair• Removing Unsound The case extent of chipping becomes
reinforcing bar position on edge side.
鉄筋を露出させる
Reinforcing bar must be exposed.
Concrete– Chipper and breaker, water
jet robot system
Carry out disposal which does not become feather edge
jet, robot system• Patching and Section Repair
– Primer or base paint of anti‐
Extent of Chipping of Concrete on Sectional Repair Method
corrosive materials– Filling with proper materials
• MethodMethod– Polishing and washing of
concrete surfaceA l i i / i– Applying primer/anti‐corrosion
– Filling materials– Curing
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Painting material for concreteTrowel plastering of
sectional repair material
Application of rust-material
Air Hole Air HoleExtent of chipping
Cutter jointReinforcing Bar
Injection Injection
Chipping up to back side of
reinforcing bar as th i About 10 mm
chipping
(b) Mortar injection
the occasion demands.
About 10 mm
(c) Shotcrete method(a) Plaster method ( ) jmethod
(c) Shotcrete method( )
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Dept. of Civil Engineering, Kasetsart University
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Dept. of Civil Engineering, Kasetsart University
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Dept. of Civil Engineering, Kasetsart University
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Dept. of Civil Engineering, Kasetsart University
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Dept. of Civil Engineering, Kasetsart University
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Dept. of Civil Engineering, Kasetsart University
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DesalinationDesalinationDept. of Civil Engineering, Kasetsart University
• Scope– Remove chloride ion from
concrete
Electrolyte Solution
External Electrode
Internal Electrode
Reinforcing Bar
– Passivate reinforcement• Outline
– Current density 1 0 A/m2 / 8
Concrete
Cl-
Cl-
Cl-
– Current density 1.0 A/m / 8 weeks
• MethodP i ti ti
MacrographElectric Power Unit
– Pre‐investigation– Treatment before supplying
electric currentSetting of receptor s stem– Setting of receptor system
– Electric current– Removal and maintenance
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Cathodic ProtectionCathodic ProtectionDept. of Civil Engineering, Kasetsart University
• Scope– To restrain the corrosion reaction from generating on the
i f treinforcement• Outline
Supplying anti corrosion current 10 mA/m2– Supplying anti‐corrosion current 10 mA/m2
– Sacrificed anode type system
AnodeOverlay
y
Concrete
Reinforcing Bar
Electric Power Unit
Protective Current
Electric Protection Method (Plane Anode,External El t i P )Electric Power)
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Dept. of Civil Engineering, Kasetsart University
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ElectroElectro‐‐deposition methoddeposition methodDept. of Civil Engineering, Kasetsart University
• For sealing crack• 6 months
Crack Sealing Clogging
AnodeElectric Power
Reinforcing Bar
Reinforcing Bar
Concrete
Concrete
Seawater
Electric PowerCoating by Electro-Deposits
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ReRe‐‐alkalization methodalkalization methodDept. of Civil Engineering, Kasetsart University
• For corbonated concrete• Alkali solution (K2CO3), 1 A/m2 direct current, 1‐2 weeks
Internal Electrode
Reinforcing Bar
Alkaline Solution
External Electrode
Alkaline solutionConcrete
Alkaline solution
Alkaline solution
Electric Power Unit
Re‐Alkalization MethodMacrograph
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Dept. of Civil Engineering, Kasetsart University
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1 Di i l St bilit
Materials for RepairMaterials for RepairConsidered Properties of Repair Materials1 Dimensional Stability
• Low shrinkage to avoid tensile cracking or debonding of the repair materials– For cementitious repair low water to binder ratio should be selectedFor cementitious repair, low water to binder ratio should be selected– Use non‐shrinking or expansive materials
2 Coefficient of Thermal Expansion‐ Should be equivalent to the substrate concreteq‐Tensile stress will develop in the material with lower coefficient at high temperature but will ‐Tensile stress develop in the higher coefficient material at low temperature.
3 Compressive Strength‐at least equal to the substrate concrete. q‐to obtain better bonding between the repair material and the substrate concrete.
4 Tensile StrengthTo ensure high cracking resistance of the repair, it is better for the repair material
to have higher tensile strength than the substrate concrete. 35
5 Bonding (Adhesion)
Dept. of Civil Engineering, Kasetsart University
5 Bonding (Adhesion)‐bond strength of the repair material should be higher than the shear strength and tensile strength of the substrate (tensile or shear crack must not occur in the repair beforestrength of the substrate (tensile or shear crack must not occur in the repair before occurring in the substrate).
6 Abrasion Resistance‐for repairing of floor, pavement, water tunnel, pier, etc..
7 Modulus of7 Modulus of Elasticity‐Equivalent of modulus ofEquivalent of modulus of elasticity of the two materials‐Preventing of debonding of the
i t i lrepair material
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Department of Civil Engineering, Kasetsart University
8 Permeabilityid i i f‐ provide resistance to penetration of
dangerous substances‐Debonding causes from the prohibit the passage of water vapor high vaporpassage of water vapor high vapor pressure (too low permeability)
9 Chemical Propertiesp‐Aware of reducing the alkalinity of the concrete substrate or nearby
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Department of Civil Engineering, Kasetsart University
10 Electrical Properties‐ high chloride environment Equivalent of resistivityg q yacceleration of corrosion due to current concentration‐ Problem of electrochemical treatment due to high resistivity repair materials
11 Consideration regarding Service Condition
• Safety during application. Ventilation, ignition of volatile materials, etc.
• Lowest and Highest Temperature that the material can be applied, for example , highest temperature for epoxy is not over 60 ‐ 80 C (cementitious materials are b f h d )better for this condition).
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Department of Civil Engineering, Kasetsart University
217547, Infrastructure System Evaluation and Retrofit 39
Department of Civil Engineering, Kasetsart University
P ibl i l ti i t i tPossible corrosion locations in concrete repair systems.
217547, Infrastructure System Evaluation and Retrofit 40