Ce diaporama a bien été signalé.
Nous utilisons votre profil LinkedIn et vos données d’activité pour vous proposer des publicités personnalisées et pertinentes. Vous pouvez changer vos préférences de publicités à tout moment.
Presented by Eng. Jude Aruna Gayan
Based on the
Fire Damage Assessment Report
Submitted by Structural Design Unit –
Defenc...
Date: 15th of February 2014
Time: 4.45 PM
Location: Lower Level 02 of Block 06 , Defence Head Quarter Complex
(DHQC) const...
Fire Damage
• Severity of fire is influenced by three parameters.
Fire load (Quantity, Type And Distribution)
Ventilation ...
• The spread of fire in Block 06 had been controlled due to the lack of
combustible materials at other areas and block wor...
Effect of Fire on Reinforced Concrete
Compressive Strength of Concrete
• Depend on temperatures, mix proportions, Couse ag...
Approximate
Temperature
Process
100°C
Simple Dilatation / Hydrothermal reactions – loss of chemically bound water
begins.
...
Elastic Modulus of Concrete
• Elastic modulus of concrete is drastically reduced if heated to temperatures in excess
of 30...
Spallation of Concrete
• Spallation involves the breaking off of layers of concrete from the exposed surface at high
and r...
Reinforcing Steel
• Steel loses its strength at high temperatures and is usually the reason if Excessive
deflections are o...
The assessment could be followed in Two methodologies,
1. Test the fire damaged concrete to directly assess the concrete q...
Proposed testing methods to determine the fire damage
Test
Location
Test
Type
Test
Method
Information Gained
Colour
change...
Class of
Damage
Element
Surface Appearance of
concrete
Structural condition
Condition of
Finish
Colour Crazing Spallation
...
More than 25 % R/F
Exposure Condition
More than 50 % R/F
Exposure Condition
Discoloration
Discoloration
Visual Assessment ...
Initial Repair Classification
Class of
Damage
Repair
Classification
Repair Requirements
0 Decoration Redecoration if requi...
Location Material Conditions
Approximate
Temperature
(°C)
1 Timber Plank(2’*4’) Ignites 240
2 Aluminium Melted 650
3 Alumi...
Temperature in fired area was greater than 650°C (Melting temperature of Aluminum), but
should less than 1100°C (Melting t...
• Provides a rapid indication of the Compressive strength of concrete.
• The Rebound of an elastic mass depends on the har...
Graph vs. Rebound Index & Compressive Strength of Concrete
For Good quality / gravel & sand aggregate / Age 14 to 56 days ...
Rebound Hammer – Schematic Diagram
Mechanism of Rebound Hammer
Procedure
• Surface preparation - Using abrasive Stone
 No Plaster
 No Paint or Dust
 No Irregularity / Aggregates
 No...
Rebound Hammer Test
Interpretation of Results
The rebound reading on the indicator scale has been calibrated by the
manufacturer of the reboun...
• Requires a Flat Surface and only appropriate for
Unspalled surfaces.
• Can be used to give an indication of Depth Of
Ser...
• The UPV equipment (e.g. PUNDIT)
 Transmitter
 Receiver
 Indicator
• Indicator shows the time for the ultrasonic pulse...
• There are three basic ways in which the transducers may be arranged.
 Opposite faces (Direct transmission)
 Adjacent f...
• The results are influenced by;
• Type of cement
• Type and size of aggregate
• Presence of reinforcement
• Moisture cond...
Concrete Quality Accordingly to Pulse Velocity.
• Uniformity and Relative quality of concrete.
• To indicate the Presence ...
Core Test
• The most direct method of estimating strength of in-situ concrete is by testing cores cut
from the structure.
...
Structural
Component
Unaffected by fire Affected by fire
Rebound
Hammer
(N/mm2)
UPV Test
(N/mm2)
Core Test
Result
(N/mm2)
...
Core Test Results
Element Location
Core Test Results
(N/mm2)
W 1 35.8
W 2 40.9
S 6 39.7
S 9 39.1
B 4 33.8
Element Location
UPV test Results
(N/mm2)
B 4 42
W 1 47.3
S 3 47.3
S 6 51.8
S 9 51.8
UPV Test Results
Rebound Hammer Test Results
Tensile Testing
Results
Comparison of damage class according to Visual Inspection with UPV,
Schmidt Hammer and Core Test Results
Visual
Inspection...
Comparison of final damage class according to Visual Inspection, UPV, Rebound
Hammer, tensile strength and Core Test Resul...
Final Class of Damage in LL1 of
Block 06
Rectification method for Structural elements
Class of Damage Rectification Methodology Construction Process
Class 00
Slabs...
Rectification method for Structural elements
Class of Damage Rectification Methodology Construction Process
Class 02
Slabs...
Rectification method for Structural elements
Class of Damage Rectification Methodology Construction Process
Class 03
Slabs...
Strengthening Beams, columns and shear walls of Class 03
Rectification method for Structural elements
Class of Damage Rectification Methodology Construction Process
Class 04
Slabs...
Repair Methods..
Main process to be undertaken in repair methods of reinforced concrete are
• Removal of damaged or weaken...
Repair Methods..
Breaking Out
• The objectives of breaking out were to remove all the deteriorated concrete and to
deepen ...
Repair Methods..
Flowable Micro-Concrete and Concrete
• The concrete for section enchasing in structural elements and larg...
Special Thank to
• Senior Design Eng. S.S.A. Kalugaldeniya
• Senior Design Eng. (Ms). Kalani Sammandapperuma
• Eng. B.A.C....
THANK YOU !!!
Assessment of fire damage and structural rectification process.
Prochain SlideShare
Chargement dans…5
×

Assessment of fire damage and structural rectification process.

4 797 vues

Publié le

A presentation on the methodology of assessing the fire damage may cause due to an in house fire and method of structural rectification can be adopted to strengthen the structure.

Publié dans : Ingénierie
  • Did You Get Dumped? Do you still want her back? If you act now, I can help you.  http://ishbv.com/exback123/pdf
       Répondre 
    Voulez-vous vraiment ?  Oui  Non
    Votre message apparaîtra ici
  • Very good and informative presentation. Thank you Sir.
       Répondre 
    Voulez-vous vraiment ?  Oui  Non
    Votre message apparaîtra ici

Assessment of fire damage and structural rectification process.

  1. 1. Presented by Eng. Jude Aruna Gayan Based on the Fire Damage Assessment Report Submitted by Structural Design Unit – Defence Head Quarter Complex Project, Sri Lanka
  2. 2. Date: 15th of February 2014 Time: 4.45 PM Location: Lower Level 02 of Block 06 , Defence Head Quarter Complex (DHQC) construction site at Akuregoda, Battharamulla Cause: Electrical leakage in the building (Possible) Damage: Stored materials and structure of the main tower of Block 06 LL2 and LL1 structural elements The Incident ...
  3. 3. Fire Damage • Severity of fire is influenced by three parameters. Fire load (Quantity, Type And Distribution) Ventilation (Area, Height, Location) Compartment (Floor Area, Surface Area, Shape, Thermal Characteristics) • In building fires, there are two regimes of combustion, Ventilation controlled fire - Occur where availability of air is limited Fuel surface controlled fire - Limit is imposed by availability of combustible materials The fire at the Block 06 Building could be categorized as 'Ventilation Controlled' type of fire.
  4. 4. • The spread of fire in Block 06 had been controlled due to the lack of combustible materials at other areas and block work constructions that had been completed around the fire initiated area. • The surrounding block works constructed around the fire initiated zone had concentrated fire in to a limited area, which had controlled the free access of air. • Remaining debris in affected area shows that, there were combustible materials such as sponge, rigifoam, safety nets stacked in a confined area of the floor slab. • This had caused fire got intensified gravely within a short period of time.
  5. 5. Effect of Fire on Reinforced Concrete Compressive Strength of Concrete • Depend on temperatures, mix proportions, Couse aggregate used and loading conditions at time of exposure. • Temperatures up to 300 °C do not seriously affect residual strengths of structural concrete. • Temperatures greater than 300 °C, Compressive strength of concrete reduces very rapidly. • A significant loss in Compressive Strength of Concrete when the temperature reaches up to 500 °C mark.
  6. 6. Approximate Temperature Process 100°C Simple Dilatation / Hydrothermal reactions – loss of chemically bound water begins. 300°C Start of temperature loss for siliceous concretes – some flint aggregates dehydrate. 100 – 400 °C Critical range for explosive Spallation / above 300 °C, large reduction in density 400- 500 °C Decomposition of calcium hydroxide / At 500°C Reduction of 50% of the concrete strength Ca(OH)2 -----> CaO + H2O 600°C Marked increase in ‘basic’ creep 700°C Dissociation of calcium carbonate 800°C Ceramic binding. Total loss of water of hydration 1200°C Melting starts Mineralogical Changes In Concrete Caused By Heating Effect of Fire on Reinforced Concrete cont.…
  7. 7. Elastic Modulus of Concrete • Elastic modulus of concrete is drastically reduced if heated to temperatures in excess of 300 °C. • Elastic deflection due to this effect is not significant in relation to other effects of fire. Effect of Fire on Reinforced Concrete cont.… Loss of Bond • Exposure to high temperatures weaken bond strength of reinforcement bars with concrete. • Loss of bond directly affects crack-width control and consequently reduce durability of the structure.
  8. 8. Spallation of Concrete • Spallation involves the breaking off of layers of concrete from the exposed surface at high and rapidly rising temperatures. • The main parameter influencing the process is Vapor pressure. Released from physically and chemically bound water in concrete pores Pressure builds up Lead to spallation • Three main types of Spallation can be identified. Explosive Spallation occurs early in the fire and proceeds with a series of disruptions, each locally removing layers of shallow depth. Sloughing off / Aggregate Spallation, also occurring in the early stages, involves the expansion and decomposition of the aggregate at the concrete surface causing pieces of the aggregate to be ejected from the surface. internal cracking due to different thermal expansion of aggregate and cement paste Corner Spallation occurs in the later stages of the fire when temperatures are lower. Occurs mainly in beams and columns, tensile cracks develop at planes of weakness such as the interface between the reinforcement and the concrete.
  9. 9. Reinforcing Steel • Steel loses its strength at high temperatures and is usually the reason if Excessive deflections are observed after a fire. • Exposure to temperatures less than 600 °C for mild steel has no significant effect in the yield strength after cooling. • If temperatures in excess of 700 °C the determination of the strength id critical to assessment. • Loss of Ductility may occur after exposure to high temperatures.
  10. 10. The assessment could be followed in Two methodologies, 1. Test the fire damaged concrete to directly assess the concrete quality. 2. Estimate the fire severity so as to deduce temperature profiles and hence to calculate the residual strength of the concrete and the reinforcement. The first methodology to directly assess the concrete quality.  Visual inspection  Non-destructive testing (E.g. rebound hammer, ultrasonic pulse velocity (UPV))  Destructive Testing (E.g. strength testing of concrete and reinforcement samples) The second methodology involves three steps to assess the residual strength and the outcome shall be verified by appropriate testing.  Evaluation of fire severity – This can be performed based on debris or applying numerical evaluation methods.  Determination of temperature profiles – This may be performed applying numerical methods or simpler calculation techniques  Assessment of residual strength of the concrete Assessment Of Fire Damage
  11. 11. Proposed testing methods to determine the fire damage Test Location Test Type Test Method Information Gained Colour changes Lateral extent of damage Depth of Damage Compressive strength of undamaged concrete Tensile strength of r/f bars On-Site Non - Destructive Visual inspection √ √ √ Rebound Hammer √ Ultrasonic Pulse Velocity √ Laboratory Destructive Core Test √ Reinforcement test √ Assessment Of Fire Damage cont…
  12. 12. Class of Damage Element Surface Appearance of concrete Structural condition Condition of Finish Colour Crazing Spallation Exposure and condition of main reinforcement Cracks Deflection / Distortion 0 Any Unaffected or beyond extent of fire 1 Column Some peeling Normal Slight Minor None exposed None None Wall Floor Very minor exposureBeam 2 Column Substantial loss Pink/red Moderate Localised to corners Up to 25% exposed, none buckled None None Wall Localised to patches Up to 10% exposed, all adheringFloor Beam Localised to corners, minor to soffit Up to 25% exposed, none buckled 3 Column Total loss Pink/Red Whitish grey Extensive Considerable to corners Up to 50% exposed, not more than one bar buckled Minor None Wall Considerable to surface Up to 20% exposed, generally adhering Small Not significantFloor Considerable to soffit Beam Considerable to corners, sides, soffit Up to 50% exposed, not more than one bar buckled 4 Column Destroyed Whitish grey Surface lost Almost all surface spalled Over 50% exposed, more than one bar buckled Major Any distortion Wall Over 20% exposed, much separated from concrete Severe and significant Severe and significant Floor Beam Over 50% exposed, more than one bar buckled Visual Assessment Go to Slide No 36
  13. 13. More than 25 % R/F Exposure Condition More than 50 % R/F Exposure Condition Discoloration Discoloration Visual Assessment Of Fired Area
  14. 14. Initial Repair Classification Class of Damage Repair Classification Repair Requirements 0 Decoration Redecoration if required 1 Superficial Superficial repair of slight damage not needing fabric reinforcement 2 General repair Non-structural or minor structural repair restoring cover to reinforcement where this has been partly lost. 3 Principal repair Strengthening repair reinforced in accordance with the load- carrying requirement of the member. Concrete and reinforcement strength may be significantly reduced requiring check by design procedure. 4 Major repair Major strengthening repair with original concrete and reinforcement written down to zero strength, or demolition and recasting.
  15. 15. Location Material Conditions Approximate Temperature (°C) 1 Timber Plank(2’*4’) Ignites 240 2 Aluminium Melted 650 3 Aluminium Melted 650 4 Piece of concrete No colour change Below 350 5 Steel Aluminium Not melted Melted 1100 - 650 6 Timber plank Ignites 240 7 Aluminium Melted 650 8 Piece of concrete Pink colour dots 350 9 Steel Not melted 1100-650 10 Plywood Ignites 240 12 Piece of concrete PVC Pink colour dots Charred 350 500 13 Iron Not melted Below 1100 14 Aluminium Steel Melted Not Melted 1100 - 650 15 Piece of concrete Pink colour dots 350 Survey on Fire Severity • An assessment of the materials burnt and the disposition of the fire provide information about likely temperatures developed and the duration at any location. • This Evaluation provides useful guide in planning more specific examination and testing for the damage area.
  16. 16. Temperature in fired area was greater than 650°C (Melting temperature of Aluminum), but should less than 1100°C (Melting temperature of Steel). Survey on Fire Severity cont… Aluminum melted Binding wire not melted Iron piece not melted Fully burnt timber plank
  17. 17. • Provides a rapid indication of the Compressive strength of concrete. • The Rebound of an elastic mass depends on the hardness of the surface against which its mass strikes. • The rebound is taken to be empirically related to the compressive strength of the concrete. • The rebound value is read from a graduated scale and is designated as the rebound number or rebound index. • The compressive strength can be read directly from the graph provided on the body of the hammer. • The results are significantly affected by :  Mix characteristics  Angle of inclination of direction of hammer  Member characteristics Test On Structural Element In The Fire Affected Area Rebound Hammer Test
  18. 18. Graph vs. Rebound Index & Compressive Strength of Concrete For Good quality / gravel & sand aggregate / Age 14 to 56 days / smooth and dry surfaces
  19. 19. Rebound Hammer – Schematic Diagram
  20. 20. Mechanism of Rebound Hammer
  21. 21. Procedure • Surface preparation - Using abrasive Stone  No Plaster  No Paint or Dust  No Irregularity / Aggregates  No spalled surfaces, • The results of this test on fire-damaged concrete, even on flat surfaces, are somewhat variable and this is perhaps due to skin hardening effects that appear to occur. • The survey is carried by dividing the member into well-defined grid points. • Take the average of about 10 readings • Should be tested against the Anvil. Ex: Type N test hammer – Nominal value (79 ± 2)
  22. 22. Rebound Hammer Test
  23. 23. Interpretation of Results The rebound reading on the indicator scale has been calibrated by the manufacturer of the rebound hammer for horizontal impact. Average Rebound Number Quality of Concrete > 40 Very good hard layer 30 to 40 Good layer 20 to 30 Fair < 20 Poor concrete 0 Delaminated
  24. 24. • Requires a Flat Surface and only appropriate for Unspalled surfaces. • Can be used to give an indication of Depth Of Seriously Weakened Concrete. Ultrasonic Pulse Velocity (UPV) Measurement - Part 4 of BS EN 12504 • Based on the Pulse Velocity Method • Provide information on the Uniformity Of Concrete, Cavities, Cracks And Defects, Presence Of Voids, Honeycombing or other discontinuities. • The pulse velocity in a material depends on its Density And its Elastic Properties which is related to the quality and the compressive strength of the concrete. • It is also applicable to indicate Changes In The Properties Of Concrete, and in the survey of structures, to estimate the Severity Of Deterioration Or Cracking.
  25. 25. • The UPV equipment (e.g. PUNDIT)  Transmitter  Receiver  Indicator • Indicator shows the time for the ultrasonic pulse to travel from the Transmitter to the receiver through the concrete. • The transducer is firmly attached to concrete surface using a Gel or Grease to vibrate the concrete. • The pulse velocity can be determined from V = L / T • The velocity of sound in a concrete is related to the concrete density & modulus of elasticity. V ~ √E/ρ V = pulse velocity (km/s) L = path length (cm) T = transit time(µs) E = modulus of elasticity ρ = density of the concrete
  26. 26. • There are three basic ways in which the transducers may be arranged.  Opposite faces (Direct transmission)  Adjacent faces (Semi-direct transmission)  Same face (Indirect transmission) Different Test Methods • Direct transmission is the Most sensitive, and indirect transmission the Least sensitive. • Indirect transmission should be used when only one face of the concrete is accessible, when the depth of a surface defect or crack is to be determined or when the quality of the surface concrete relative to the overall quality is of interest.
  27. 27. • The results are influenced by; • Type of cement • Type and size of aggregate • Presence of reinforcement • Moisture condition • Compaction • Age of concrete • Comparatively Higher velocity indicate Concrete Quality is Good in terms of density, uniformity, homogeneity etc.
  28. 28. Concrete Quality Accordingly to Pulse Velocity. • Uniformity and Relative quality of concrete. • To indicate the Presence of voids and cracks, and to evaluate the effectiveness of crack repairs. • When used to monitor changes in condition over time, test locations are to be marked on the structure to ensure that tests are repeated at the same positions. • The Degree of saturation of the concrete affects the pulse velocity. • The pulse velocity is independent of the dimensions of the test object provided reflected waves from boundaries Significance & Use
  29. 29. Core Test • The most direct method of estimating strength of in-situ concrete is by testing cores cut from the structure. • A limited number of test cores were extracted from the fire damaged area to minimize further damage. Tensile Test on Reinforcement Steel • Rebar samples were taken from representative elements of damaged structural members. • The samples were tested for yield, elongation , ductility and tensile strength.
  30. 30. Structural Component Unaffected by fire Affected by fire Rebound Hammer (N/mm2) UPV Test (N/mm2) Core Test Result (N/mm2) Rebound Hammer (N/mm2) UPV Test (N/mm2) Core Test Result (N/mm2) Slab 1 53-55 - - 30-33 47.3 - Slab 2 55-57 51.8 39.1 22-48 51.8 39.7 X Direction Beam 1 35-44 - - 28-42 42 33.8 Y Direction Beam 1 46-57 - - 37-46 - - Column 1 38-48 - - 32-44 - - Wall 1 37-42 - 40.9 37-39 47.3 35.8 Comparison of Results
  31. 31. Core Test Results Element Location Core Test Results (N/mm2) W 1 35.8 W 2 40.9 S 6 39.7 S 9 39.1 B 4 33.8
  32. 32. Element Location UPV test Results (N/mm2) B 4 42 W 1 47.3 S 3 47.3 S 6 51.8 S 9 51.8 UPV Test Results
  33. 33. Rebound Hammer Test Results Tensile Testing Results
  34. 34. Comparison of damage class according to Visual Inspection with UPV, Schmidt Hammer and Core Test Results Visual Inspection Class Structural Element UPV Test (N/mm2) Core Test (N/mm2) Rebound Hammer(N/mm2) Tensile Strength of R/F (N/mm2) Class 04 S1 - - 35.3 - 55.4 - S2 - - 38.7 - 49.7 460 - 350 S3 47.3 - 30.1 – 33.0 460 - 350 S4 - - 22.1 -47.9 460 - 350 S5 - - 30.1 – 31.8 350 - 250 S6 51.8 39.7 46.0 - 49.7 > 460 Class 03 B2 - - 46.0 - B3 - - 22.1 – 37.0 460 - 350 B4 42.0 33.8 28.5 -42.4 > 460 B5 - - 37.0 – 46.0 - W1 47.3 35.8 37.0 – 38.7 460 - 350 C1 - - 31.8 – 44.1 - Class 02 B1 - - 35.2 – 42.4 - B6 - - 35.3 – 44.1 - B7 - - 37.0 – 44.1 - B8 - - 38.7 – 40.5 > 460 S7 - - - - S8 - - - - Class 01 B9 - - - - W2 - 40.9 38.7 – 40.5 - C2 - - 38.7 – 47.9 - Class 00 S9 51.8 39.1 55.4 – 57.3 - Slide No 14
  35. 35. Comparison of final damage class according to Visual Inspection, UPV, Rebound Hammer, tensile strength and Core Test Results Final Damage Class Structural Element Visual Inspection Class UPV Test (N/mm2) Core Test (N/mm2) Rebound Hammer (N/mm2) Tensile Strength of R/F (N/mm2) Class 04 S2 Class 04 - - 38.7 - 49.7 460 - 350 S3 -do- 47.3 - 30.1 – 33.0 460 - 350 S4 -do- - - 22.1 -47.9 460 - 350 S5 -do- - - 30.1 – 31.8 350 - 250 B2 Class 03 - - 46.0 - B3 -do- - - 22.1 – 37.0 460 - 350 B8 Class 02 - - 38.7 – 40.5 > 460 Class 03 S1 Class 04 - - 35.3 - 55.4 - S6 -do- 51.8 39.7 46.0 - 49.7 > 460 B4 Class 03 42.0 33.8 28.5 -42.4 > 460 B5 Class 03 - - 37.0 – 46.0 - B6 Class 02 - - 35.3 – 44.1 - B7 -do- - - 37.0 – 44.1 - W1 Class 03 47.3 35.8 37.0 – 38.7 460 - 350 C1 -do- - - 31.8 – 44.1 - Class 02 S7 Class 02 - - - - S8 -do- - - - - B1 Class 02 - - 35.2 – 42.4 - W2 Class 01 - 40.9 38.7 – 40.5 - C2 -do- - - 38.7 – 47.9 - Class 01 B9 Class 01 - - - - Class 00 S9 Class 00 51.8 39.1 55.4 – 57.3 -
  36. 36. Final Class of Damage in LL1 of Block 06
  37. 37. Rectification method for Structural elements Class of Damage Rectification Methodology Construction Process Class 00 Slabs Beams, columns and shear walls Redecoration if required  Surface cleaning  Mortar application Class 01 Slabs Beams, columns and shear walls Superficial repair of slight damage not needing fabric reinforcement  Surface cleaning  Breaking out damaged area - Hammer and chisel  Mortar application
  38. 38. Rectification method for Structural elements Class of Damage Rectification Methodology Construction Process Class 02 Slabs Beams, columns and shear walls Non-structural or minor structural repair restoring cover to reinforcement where this has been partly lost.  Surface cleaning  Breaking out damaged area - Hammer and chisel ( Small areas) - Electrically or Pneumatically powered breakers (Large areas)  Mortar application  Concreting - Non-Shrinkage, flowable construction grout
  39. 39. Rectification method for Structural elements Class of Damage Rectification Methodology Construction Process Class 03 Slabs Strengthening repair reinforced in accordance with the load- carrying requirement of the member. Concrete and reinforcement strength may be significantly reduced requiring check by design procedure.  Surface cleaning  Breaking out the entire damaged slab area - Electrically or Pneumatically powered breakers . - Hydro- demolition  Connection Reinforcement - Lapping - Coupling - Welding - Not recommended  Concreting - Conventional concrete Beams, columns and shear walls Strengthening repair reinforced in accordance with the load- carrying requirement of the member. Concrete and reinforcement strength may be significantly reduced requiring check by design procedure.  Surface cleaning  Breaking out damaged area - Hammer and chisel ( Small areas) - Electrically or Pneumatically powered breakers (Large areas)  Connection Reinforcement - Lapping - Coupling - Welding - Not recommended  Concreting - Non-Shrinkage, flowable construction grout
  40. 40. Strengthening Beams, columns and shear walls of Class 03
  41. 41. Rectification method for Structural elements Class of Damage Rectification Methodology Construction Process Class 04 Slabs Major strengthening repair with original concrete and reinforcement written down to zero strength, or demolition and recasting.  Surface cleaning  Breaking out entire damaged slab area - Electrically or Pneumatically powered breakers - Hydro-demolition  Connection Reinforcement - Lapping - Coupling - Welding - Not recommended  Concreting - Conventional Concrete Beams, columns and shear walls Major strengthening repair with original concrete and reinforcement written down to zero strength, or demolition and recasting.  Surface cleaning  Breaking out the entire damaged area - Electrically or Pneumatically powered breakers  Connection Reinforcement - Lapping - Coupling - Welding - Not recommended  Concreting - Conventional Concrete
  42. 42. Repair Methods.. Main process to be undertaken in repair methods of reinforced concrete are • Removal of damaged or weakened concrete • Replacement of weakened reinforcement • Replacement of concrete to to provide adequate structural capacity, durability and fire resistance. Surface Cleaning • Pressure water jetting and in some areas power wire brushing and cementitious Paint coat were used dependent upon the degree of discoloration. • Surface cleaning may be required prior to the commencement of any repair works to enable the clear identification of areas.
  43. 43. Repair Methods.. Breaking Out • The objectives of breaking out were to remove all the deteriorated concrete and to deepen the repair area without damage to the concrete and reinforcement that are to remain in place • Hammer and chisel, electrically powered breakers were used for breaking out. • The Braking pattern was determined to avoid any sudden collapse and to un-effect to the sound concrete. • Sledgehammer and Chemical blasting were prohibited.
  44. 44. Repair Methods.. Flowable Micro-Concrete and Concrete • The concrete for section enchasing in structural elements and large filling volumes were rectified using a Concrete mix of Construction grout and chip concrete with proportion of 3:1. • The filling area less than 50 mm were rectified with an Construction grout mortar mix with specified water cement ratio.
  45. 45. Special Thank to • Senior Design Eng. S.S.A. Kalugaldeniya • Senior Design Eng. (Ms). Kalani Sammandapperuma • Eng. B.A.C. Batepola - In Charge / Site Laboratory
  46. 46. THANK YOU !!!

×