Maintenance and repair strategies - Repair and rehabilitation of structures(RRS)

DEPARTMENT OF CIVIL ENGINEERING
CE6021-REPAIR AND REHABILITATION OF STRUCTURE
UNIT I – MAINTENCE AND REPAIR STRATEGIES
PREPARED BY
SHANMUGASUNDARAM NAGARAJ
ASSISTANT PROFESSOR
REPAIR & REHABILITATION OF
STRUCTURES
CE6021 - RRS / unit 1
by,Shanmugasundaram.N
SNS COLLEGE OF ENGINEERING
12/4/20201/46

2/46
UNIT I
MAINTENANCE AND REPAIR STRATEGIES 9
Maintenance, Repair and Rehabilitation, Facets
of Maintenance, importance of Maintenance,
Various aspects of Inspection, Assessment
procedure for evaluating a damaged structure,
causes of deterioration.
12/4/2020

REPAIR
It refers to correct the deteriorated or faulty materials, modification of a structure,
partly or wholly , which is damaged in appearance or serviceability
Umbrella term that includes all types of work done at a site or on real property,
including alterations, painting, remodelling, transportation of construction and
furnishing goods and material etc., undertaken by a contractor or sub-contractor.
REHABILITATION
It is the process of restoring the structure to service level, once it had and now
lost.
Strengthening consists in endowing the structure with a service level, higher than
that initially planned by modifying the structure not necessarily damaged area.
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REPAIR
REHABILITATION
by,Shanmugasundaram.N 12/4/20204/46

MAINTENANCE
Maintenance of building is defined as the work done to keep the civil Engineering
structures in working condition so as to enable them to carry out the functions for which
they are constructed.
The maintenance of structure is done to meet the following objectives
1.Prevention of damages due to natural agencies and to keep them in a good
appearance and working condition
2.Repair of the defects occurred in the structure and strengthen them, if necessary.
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OBJECTIVES OF MAINTENANCE:
• To preserve in good condition buildings and services.
• When deterioration occurs due to any reason it is inevitable to restore it to its original
standard.
• To make improvements whenever required.
• To sustain utility value.
A good maintenance team has to ensure
1. Safety
2. Efficiency
3. Reliability
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Maintenance operations include:
Emergency maintenance: Necessitated by unforeseen breakdown
drainage or damage caused by natural calamity like fire, floods, cyclone
earthquake etc.
Condition Based maintenance: Work initiated after due inspection
Fixed time maintenance: Activities repeated at predetermined intervals
of time.
FACETS OF MAINTENANCE
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Classification of Maintenance Work:
· Preventive Maintenance
· Remedial Maintenance
· Routine Maintenance
· Special Maintenance
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Preventive Maintenance:
Before the defects occurred or damages developed

Remedial Maintenance:
 After the defects or damage occurs in the structures.
 It involves the following basic steps.
Finding the deterioration:
 Determining the causes.
 Evaluating the strength of the
existing structures.
 Evaluating the need of the
structures.
Selecting and implementing the
repair procedure

by,Shanmugasundaram.N 12/4/2020
11/46

Routine Maintenance:
 Maintenance attended to the structure periodically.
 It depends upon specifications and materials of structures ,purpose , intensity
and condition of use .It is done by the fund provided annually, which is normally
1.5% of the cost of construction.
It includes the inspection, planning the program and executing the same.
It includes white washing, patching repair to plaster, replacement of fitting and
fixtures, blinding of road surface.

Special Maintenance:
 work not covered in routing program or the annual repair is done under special
condition
 It may be done for strengthening and updating of the structure to meet the new
condition of usage or to increase its serviceability.
It include particular or complete renewal, such as renewal of floors, roofs etc

Special Maintenance

Maintenance operations have manyother facets such as :
 Condition based
maintenance :
 Fixed time
maintenance :
 Preventative
maintenance :
 Opportunity
maintenance :
 Day to day
maintenance :
 Shutdown
maintenance :
 It is the work initiated after
inspection.
 Activities repeated at
predetermined intervals.
 This is intended to preserve by
preventing failure and detecting
incipient faults.
 Work done as and when possible
within the limits of operational
demand.
 Its involves maintenance that has
to be performed daily.
 Thorough overhaul and
maintenance after closing.
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Preventive maintenance:
This is intended to preserve by preventing failure and
detecting incipient faults ( Work is done before failure takes place)
Opportunity maintenance:
Work did as and when possible within the limits of operation
demand.
Day-to-Day care and maintenance
Shut down maintenance: Thorough overhaul and
maintenance after closing a facility.
Improvement plans: This is essentially maintenance
operation wherein the weak links in the original construction are
either replaced by new parts or strengthened.
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NECESSITY OF MAINTENANCE:
The maintenance of structure is done to meet the following objectives
1.Prevention of damages due to natural agencies and to keep them in a good
appearance and working condition
2.Repair of the defects occurred in the structure and strengthen them, if necessary.
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Atmospheric Agencies
 Normal Wear And Tear
Failure Of The Structure
NECESSITY OF THE MAINTENANCE
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a)Atmospheric agencies
(i) Rain : It is the important source of water, which affects the
structure in the following ways;
Physical:
 Dissolving and carrying away minerals as it is universal solvent.
 Expansion and contraction – The materials is subjected to repetitive
expansion and contraction while they become wet and dry and
develops the stresses.
 Expansion of water – The variation of temperature causes the
expansion and contraction of absorbed water and affects the micro-
structures of the materials.
 Erosion – Transportation and attrition and abrasion of the materials is
quite evident effect of the water.
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
. (ii) Chemical:
The water available in nature contains acids and alkaline and other
compound in dissolved form acts over the material to give rise, which
is known as chemical weathering.
(iii) Wind: It is the agent, which transports the abrasive material and
assists the physical weathering. Its action is aggravated during rains
and when it is moving with high speed, it may contain some acidic
gases like CO2 fumes which may act over the material and penetrates
quite deeply in the materials and structure.
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 (iv) Temperature: The seasonal and annual variation of the
temperature, difference in temperature in two parts of the materials
and the surface of material causes expansion and contraction. By
this movement of the material bond and adhesion between them is
lost when it is repeated.
This is responsible for the development of cracks and the rocks may
break away into small units.
 Exploitation or peeling off the shell takes place if exterior layer
are heated externally with respect to internal layers.
The temperature variation may also cause change in the structure
and chemical composition of the material.
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b) Normal Wear and tear
During the use of structure it is subjected to abrasion and thereby it
looses appearance and serviceability.
c) Failure of structure
Failure is defined as behaviour of structure not in agreement with
expected condition of stability or lacking freedom from necessary
repair or non- compliance with desired use of and occupancy of the
completed structure.
In field it may result in visual collapse of the structure or even
suspension of the services e.g. the collapse of towers, sliding or over
turning of dam, settlement of foundation, crushing of columns etc.
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The causes of failure may be broadly grouped as:
Improper Design : Due to incorrect, insufficient data regarding
use, loading and environmental conditions, selection of material and
poor detailing.
Defective Construction: Poor materials, poor workmanship,
lack of quality control and supervision
Improper use of structure: Overloading, selecting the
structure for the use for which they are not designed such as
deteriorating environment due to impurities from industrial fuel
burning, sea water minerals, chemicals, storage of chemicals etc.
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 Lack of maintenance:
Lack of upkeep, proper protection, precaution and
preservation, deteriorated the structure, which may result in the
failure.
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1.Improves the life of structure
2.Improved life period gives better return on investment
3.Better appearance and aesthetically appealing Leads to quicker
detection of defects and hence remedial measures
4.Prevents major deterioration that leads to collapse
5.Ensures safety to occupants
6.Ensures feeling of confidence by the user
NECESSITY OF THE MAINTENANCE
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
Maintenance is a continuous cycle involves every element of
building
•Structural
•Electrical wiring
•Plumbing-Water supply-Sanitation
•Finishes on floors and walls
•Roof terrace
•Service platform/Verandah
•Lifts
•Doors, Windows and other elements
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 PRE-MONSOON PERIOD
Cleaning of drains, checking of roof leakages, collection of
materials and equipments require during monsoon repairs, bridges
and other structure which are not easily approachable during the
monsoon
 MONSOON PERIOD Washing away of roads, railway tracks,
collapse of roof and failure of walls
 POST-MONSOON PERIOD Replacement and rehabilitation work
INSPECTION PERIODS
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The following are the various maintenance aspects,
Daily Routine Maintenance`
Weekly Routine Maintenance
Monthly Routine Maintenance
Yearly Routine Maintenance
VARIOUS ASPECTS INSPECTION
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 Basically an inspection oriented and may not contain action to be
taken.
 Help in identifying major changes, development of cracks, identifying
new cracks etc.
 Inspection of all essential items by visual observation.
 Check on proper function of sewer, water lines, wash basins, sinks
etc.
 Check on drain pipes from roof during rainy season
Daily Routine Maintenance`
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Electrical accessories
Cob webs cleaning
 Flushing sewer line
 Leakage of water line
Weekly Routine Maintenance
Monthly Routine Maintenance
Cleaning doors, windows etc
Checking septic tank/sewer
 Observation for cracks in the elements
Cleaning of overhead tanks
Peeling of plaster, dampness, floor cracks
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Attending to small repairs and white washing.
Painting of steel components exposed to weather.
Check of displacements and remedial measures.
Yearly Routine Maintenance
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1) INSPECTION
Collect data at specified intervals in specified form
2) ANALYSIS
i)Add latest information to database which contains all earlier
information
ii)Examine progression of defects
iii)Relate defects to action criteria
STAGES OF INSPECTION AND
MAINTENANCE
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3) ACTION POSSIBILITIES
i) Note and wait for the next inspection
ii) Alter inspection frequency
iii) Institute repairs
iv) Further detailed investigation
v) Put safety procedures in place
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ASSESMENT PROCEDURE FOR
EVALUATING DAMAGES IN A STRUCTURE
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PHYSICAL
INSPECTION
STUDY OF DOCUMENTS
ESTIMATE OF LOAD ACTING
ESTIMATE OF ENVIRONMENTAL
EFFECTS
DIAGNOSIS
RETROSPECTIVE ANALYSIS
IS DIAGNOSIS CONFIRMED
MATERIAL
TESTS
36/35CE6021 - RRS / unit 1
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ASSESSING OF
STRUCTURAL
ADEQU ACY
LOAD
TESTS
ESTIMATE
OF
FUTUR E
USE
CHOICE OF
COURSES OF
ACTION
37/35CE6021 - RRS / unit 1 by,Shanmugasundaram.N 12/4/202037/46

For assessment of damage of a structure the following general considerations
have to be taken into account.
 Physical inspection of damaged structure.
 Preparation and documenting the damage.
 Collection of samples and carrying out tests both in situ and in lab.
 Studying the documents including structural aspects.
 Estimation of loads acting on the structure.
 Estimate of environmental effects including soil structure interaction.
 Diagnosis.
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Taking preventive steps not to cause further damage.
 Retrospective analysis to get the diagnosis confirmed.
 Assessment of structural adequacy.
 Estimation of future use.
 Remedial measures necessary to strengthen and repairing the
structure.
 Post repair evaluation through tests.
 Load test to study the behavior.
 Choice of course of action for the restoration of structure.
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Schmidt Rebound Hammer Test
Ultrasonic Pulse Velocity
Pull out and Pull off Tests
Break off
Core Test
Windsor Probe
Pulse Echo Technique
STRENGTH TEST
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Corrosion Test
Absorption and Permeability
Test for Alkali Aggregate Reaction
Abrasion Resistance Tests
Rebar Locator Test
DURABILITY TEST
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 Infrared Thermograph Test
 Radar Test
 Radiography and Radiometry Tests
 Acoustic Emission
 Optical Fibre Test
 Impact Echo Tests
 Load Testing test
 Dynamic Response
 X-Ray Diffraction
PERFORMANCE AND INTEGRITY
TEST
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Carbonation test
Suphate Determination Test
Chloride Determination Test
Thermoluminescence Test
Thermo gravimetric analysis Test
Differential Thermal analysis
Diatometric Test
CHEMICAL TEST
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The process that adversely affects the performance of a structure
over time due to defects and damages occurred by naturally occurring
chemical, physical or biological actions, repeated actions such as those
causing fatigues, normal or severe environmental influences and wear
due to use, abuse and others.
DETERIORATION (மமோசமடைவது)
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Design and construction flaws Environmental effects
Usage of poor quality material Quality of supervision Deterioration due to
corrosion
Spalling of concrete cover
Cracks parallel to the reinforcement
Spalling at edge
Swelling of concrete
Dislocation
Internal cracking & reduction in area of steel reinforcement
CAUSES OF DETERIORATION
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