RECO2006 Construction IV
Building Pathology
Edward CY YIU Department of Real Estate and Construction January
2007
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Intended Learning Outcomes What is building pathology?
Articulate the requirements of a buildings Synthesize the
principles of building pathology Mainly focus on concrete
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Repairs on repairs A commonly phenomenon in both health care and
building care. No evaluation of medical treatment / repairs
Frequent repeated symptoms Even worse than before
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What is Building Pathology? Pathology? Crime Detection? Forensic
Medicine? Epidemiology? Anatomy? Micrology?
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AEEBC Definition Building Pathology is the: Identification,
investigation and diagnosis of defects in existing buildings;
Prognosis of defects diagnosed, and recommendations for the most
appropriate course of action having regard to the building, its
future and resources available; and Design, specification,
implementation and supervision of appropriate programmes of
remedial works, and monitoring and evaluation of remedial works in
terms of their functional, technical, and economical performance in
use. 5 (AEEBC, 1994 quoted by Watt, 1999, p.1)
CIB Definition Building Pathology is the: Systematic treatment
of building defects, their causes, their consequence and their
remedies. (CIB W86, 1993 quoted by Watt, 1999, p.1)
The principles of Building Pathology rely on A detailed
knowledge of how building is designed, constructed, used and
changed, and the various mechanisms by which its structure,
materials and environmental conditions can be affected. i.e. our
course aims and objectives!!! (Watt, 1999, p.2)6
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Harris (2001) Analogyrepair
Disease
Treatmentdiagnosis
Interventions Mechanismprevention
Pathology Healthy HUMAN BODY
Building Pathology
Symptoms
Healthy and Safe Symptoms BUILDING assessmentrequirements
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What is Building Diagnosis? Building Diagnosis is a study of the
causes of the symptoms It is a scientific research It requires
hypotheses testing It needs statistical analysesSymptoms Hypotheses
Analyses Intervention Strategies Assessments
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Generalist and Specialist Diagnosis: A generalist
Repair: A specialist
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Current Practice Report symptoms Search for cookbook solutions
Carry out repair works (cosmetic or cover-up symptoms) Repeated
symptoms Total replacementSymptoms Intervention
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Why Building Professionals do not diagnose? Building is much
cheaper than human lives Building system is much simpler than human
system Building system can be replaced much easier than human
system Building repair is carried out by nonprofessional Very few
professional negligence claims in building repairs 11
Where building pathology is treasured? Heritage repair
Replacement of building systems do harms to the value of the
heritage
Then why building pathology is taught? Professionalism and
ethics Value of the profession
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Symptoms The Symptom (visible manifestation of failure) provides
the first clue to cause of defect, and suggests scope and nature of
investigation. [E.g. Fever] seepage, concrete spalling, debond,
delamination, etc.13
What next? [If fever then panadol?] What is healthy? Observe and
assess symptoms , Inspections and tests , Diagnose causes of
symptoms , Cure , Protection and prevention , , Evaluation /
feedback 14
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Corrosion Management in Reinforced Concrete Structures Sika
(2005): The Key Stages Assessment Survey of the Condition of the
Structure Diagnosis of the Causes of Deterioration Determine the
Repair and Protection Objectives Select the appropriate Repair and
Protection Strategy Definition of the future Maintenance
Requirements and Procedures15
Requirements (What is healthy?) Functional Requirements
Performance Requirements Statutory Requirements User Requirements
Others Intended design life and durability Environmental impacts
Future requirements Costs of alternative solutions Consequences and
likelihood of failure16
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Assessment The current condition of the structure (visible,
non-visible and potential defects) Symptoms, performance
Review of the past, current and future exposure Design,
Specifications, Materials, Workmanship Operations, Maintenance
records Exposure17
Survey and Assessment Preliminary site visit Background research
? Desktop study Inspection or survey Report writing Assessment of
defects Severity of defects Effect and consequences of the defect
Cost of remedial works (Watt, 1999, p.145)18
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Scope of an Assessment:
The nature of the defect The accuracy with which the cause need
to be identified The main reason for wanting to know why the defect
has occurred How to achieve the accuracy? Visual inspection Non
destructive tests Extensive opening up19
Sources of Information
Drawings and spec Architects instructions Site notes, minutes,
reports Maintenance manuals and records Reports on the defects
Interviews Meteorological records Inspections Published information
Tests/measurements20
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Diagnosis [] No cookbook approach? if fever then panadol? The
most difficult part of pathology What cause high body temperature?
Influenza? SARS? Bird Flu? Different causes, different cures Wrong
diagnostic analysis, fatal treatment!
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Buildings Department (2002) Building Maintenance Manual -
Cookbook Solutions?!
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Causes of defects [What are the causes of lung cancer? Smoking?
Multiple causes? What are the primary causes?]
How to determine? By elimination By hypotheses testing
(statistics) By laboratory investigations By simulations23
Diagnosis Approach Observations (Visual Inspections) Assumptions
Hypotheses Tests - differentiate among hypotheses Extensive opening
up Destructive tests Non-destructive tests By logical elimination
By statistical means24
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Causes
Four basic causes: Genetics Living style Environment and
accident Ageing Design and Specifications Materials and Workmanship
Operations and Maintenance Environmental Impacts Ageing Process
Vandalism and Incompatible change25
Six basic causes of building defects:
Testing Standards STANDARD TEST METHODS FOR CONCRETE
STRENGTHSurface hardness test (Rebound hardness) Penetration
resistance test (Windsor probe) Pull-off test Pull-out test
Break-off test Ultrasonic pulse velocity C597-97 C900-01
American StandardsC805-02 C803/803M-97e1
British StandardsBS EN 12504-2:2001 BS 1881-207:1992 BS
1881-207:1992 BS 1881-207:1992 BS 1881-207:1992 BS
1881-203:1986
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Repair Strategy
To meet future requirements of the structure:Do nothing
Downgrade the structure or its capacity Prevent or reduce further
damage without repair Improve, refurbish or strengthen Immune
Demolition
Discuss the following symptoms: Asbestos in wall panels Water
seepage from construction joints27
Repair (Intervention Approach) Abstention Mitigation
Reconstitution Circumvention Acceleration (Harris, 2001, p.39)
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AbstentionEntropy
No interventionHalf Life
Time Incipient Accelerating Decelerating29
Mitigation and Reconstitution
Mitigation: alter the environment that support the deterioration
mechanism
Reconstitution: alter the fabric that was deteriorating
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Circumvention and Acceleration
Circumvention: Substitution of other materials and functions
Acceleration: Speed up the rate of deterioration
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My Ideal - ImmunizationBohm and Peat (2000, p.236) There are
three ways of dealing with the problem: 1. Avoid the introduction
of misinformation in the first place, for example, by keeping away
from infection through good sanitation and a careful diet. 2. Where
misinformation exists, it may be possible to do something to remove
it through various kinds of medical intervention. 3. But more
significantly, the immune system is able to clear up misinformation
in a natural way.
Immunization: automatic clear up deterioration and combat the
source of deterioration Intelligent Maintenance See Yiu and Yau
(2006)32
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Bohm and Peat (2000, p.237)The immune system itself is
particularly complex and contains a very subtle kind of information
that can respond to the whole meaning of what is happening to the
order of the body. In this way it is able to distinguish
misinformation from information needed for the bodys healthy
operation. It can be compared to a kind of intelligence that works
within the body. Moreover there is evidence that this sort of
intelligence can respond to the higher levels that are usually
associated with thought and feeling. It is well known that
depressing thoughts can inhibit the activity of the immune system,
with the result that a person becomes more susceptible to
infections. Indeed there is much evidence that a vigorous, creative
state of mind and a strong will to live are conducive to general
health and even to recovery from dangerous illnesses. (Norman
Cousins, Anatomy of an Illness, Bantam, NY, 1981) More generally,
it could be said that good health is basically a manifestation of
the overall creative intelligence, working in concert with the
body, through various means that include exercise, diet,
relaxation, and so on.33
Intervention MatrixExample: Cracks in rooftop waterproof
membraneAbstention Do nothing Mitigation Redirect source of water
Reconstituti on Re-roofing Circumventio Acceleration n Spray
plastic Demolition layer
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Intervention MatrixExample: Cracks in rooftop waterproof
membrane
Immunization
Clotting of the cracks
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Evaluation of Repair Re-test (Acceptance Criteria) Performance
Monitoring Before-after Comparison Feedbacks
Discuss: the costs of Repair on Repair How to ensure repair
cures the disease?36
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Prevention and Protection Maintenance Maintenance Management
(Preventive) Periodic Inspections or Replacements Continuous
Monitoring Smart Materials and Intelligent BMS Built-in Automatic
Feedback System Protection or Upgrading / Strengthening37
Emmons, 1993, p.44
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Methods of Protection
Emmons, 1993, p.44
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Recommended Reading Watt, D.S. (1999) Building Pathology:
Principles and Practice, Blackwell Science, UK. Harris, S.Y. (2001)
Building Pathology: Deterioration, Diagnostics, and Intervention,
John Wiley & Sons, Inc.: NY. Emmons P.H. (1994) Concrete Repair
& Maintenance. R.S. Means Co. Inc., Kingston, MA. Buildings
Department, (2002), Building Maintenance Manual, The Government of
the Hong Kong SAR. Buildings Department, (1998), Interim Technical
Guidelines on The Inspection, Assessment and Repair of Buildings
for The Building Safety Inspection Scheme, The Government of the
Hong Kong SAR. CITA (2000) Reinforced Concrete Defect Diagnosis
& Remedy Course Materials. 40
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Further Readings AEEBC (1994) Academic Guidelines: Policy
regarding degree validation. London and Brussels: Association
dExperts Europeans du Batiment et de la Construction. CIB W86
(1993) Introduction, CIB Report 155, Jun. CIB W86 Building
Pathology Marshall D., Worthing D., et al (1998) Understanding
Housing Defects Estates Gazette. Hinks J, Cook G (1997) The
Technology of Building Defects, E&FN Spon. Watt David (1999)
Building Pathology Blackwell Science ISBN: 0632048751 Glover Peter,
(2000) 4th ed Building Surveys Butterworth-Heinemann ISBN 07506
53019 Bonshor RB, Bosnhor LL (1996) Cracking in Buildings BRE Singh
Jagit (1994) Building Mycology E&FNSpon Macdonald Susan, (2002)
Concrete: Building Pathology, Blackwell Publishing41
Further Readings Leung, A.Y.T. and Yiu, C.Y. eds (2003) Building
Dilapidation and Rejuvenation Joint Imprint of Hong Kong Institute
of Surveyors and City University of Hong Kong Press Addleson Lyall
(1992) Building Failures - A guide to diagnosis, remedy and
prevention, 3rd ed, Butterworth-Heinemann Ltd. Chudley R, Greeno R
(1999) Advanced Building Construction, Pearson Education, pp193-204
Curwell S R, March C G, (1986) Hazardous Building Materials - A
guide to the selection of alternatives E&FN Spon Ransom W. H.
(1987) Building Failures - Diagnosis and Avoidance 2nd ed E&FN
Spon. Everett, Alan. (1994) Materials. - 5th ed.. - Harlow :
Longman Scientific & Technical, (Mitchell's building series)
Sanderson W J H (2004) Asbestos for Surveyors Estates Gazette
Melville I A, Gordon A (2004) Inspections and Reports on Dwellings
- Accessing Age, EG Books Sika (2005) Technology and Concepts for
the Repair and Protection of Reinforced Concrete, Sika Services AG,
Switzerland.42
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Further Readings Hollis M.(2000), Surveying Buildings, 4th ed,
RICS Books. ISBN: 0854069798, Oliver Alan, James Douglas et al
(1997) 2nd ed, Dampness in Buildings, Blackwell Publishing, ISBN
0632040858 The Institute of Structural Engineers (1994) Subsidence
of Low Rise Buildings SETO Ltd. Cook K., Hinks J., (1992)
Appraising Building Defects Longman Scientific & Technical.
Freeman T. J., Littlejohn G. S. et al (1994) Has Your House Got
Cracks? Thomas Telford.
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Further Readings (contd) Gleeson John (1994) Structural Failures
in Traditionally Built Domestic Buildings. HAPM (2000) HAPM Guide
to Defects Avoidance E&FN Spon. CIB/W086 Second International
Symposium on Building Pathology, Durability and Rehabilitation,
Lisbon, Portugal, 6-8th November 2003 Holland R., Montgomery-Smith
B. E. et al eds (1992) Appraisal and Repair of Building Structures
- Introductory Guide Thomas Telford Richardson B A (1990) Defects
and Deterioration in Buildings E&FN Spon Macdonald S. (2001)
Building Pathology (Concrete) Blackwell Science, ISBN:
0632052511
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The EndFor enquiries, please send email to Edward CY
YIUDepartment of Real Estate and Construction The University of
Hong Kong
[email protected]
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