Challenges in managing structural asset portfolios in the Middle East

1 Concrete Maintenance Workshop - Faiz M Khan
Challenges in managing ageing
structural asset portfolios
Faiz M Khan
CH2M HILL
28th November 2013
28 November 2013

2 Concrete Maintenance Workshop – Faiz M Khan
Safety Moment
• Assess your journey
• Prepare
• Check
• Slow down
• Use headlights
• Wait it out
• Do not use cruise control
• Track the car ahead of you
• Stay toward the middle lanes
• Avoid lane changes
• Give trucks and buses extra distance
• Stay out of moving water
28 November 2013

Challenges….
• Original challenges and transformation of the industry
• Where do we stand today – technology available
• The next challenge – how do we maintain structural assets?
28 November 2013

Transformation of the concrete industry in region
• Original challenge:
• Highly aggressive regional climatic conditions
• Poor quality materials
• Growing infrastructure investment
• Lack of experienced local contractors
• Outcome:
• Regional concrete construction sector has transformed over 30-40 years
• From: fraught with problems
• To: capable of achieving high performance and long-life durability
28 November 2013

Contrasts with other regions
• Climatic effects
• High temperature
• typ. ~15-20°C > London
• typ. design over 100-year life
5 - 55°C shade
• Very high sunshine levels
• Low precipitation (about 10% of London)
• Natural environmental effects
• High salinity in the sea
• High salinity in the ground
• Man-made environmental effects
• Higher salinity in industrial plants
Mean monthly high temperature (C)
0
5
10
15
20
25
30
35
40
45
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Dubai
London
A World ocean salinity chart o
oo
34
35
35
35 34
38
36
3736
35
33
34
35
35
36
35
34 34
34
35
35
36
36
34
35
3534
33
40
40-50+
36
37
35
A World ocean temperature chart
10
10
10
10
10
15
20
25
25
20
25
25
10
15
20
25
25
20 15
15
20
25
25 25
20
15
10
25
30
30
30
o
C
28 November 2013

Physical effects of climate
• High temperatures and low precipitation:
• High evaporation rates
• Hot dry materials
• Coastal strip:
• High water table
• Highly saline ground water
• Extreme drying and salinity:
• Potential for lower as-built quality …
• … and faster deterioration in-service
J F M A M J J A S O N D
0
2
4
6
8
10
Dailyevaporation/rainfall-mm
Gulf
location
Typical daily
evaporation
Typical daily
rainfall
28 November 2013

Physiological effects of climate
• Construction quality
= materials quality
+ workmanship
• Humans are vulnerable to:
• temperature
• humidity / evaporation
• solar radiation
• Summer months are extreme for human physiology
• Demanding to expect good quality from a workforce that is toiling in
‘uncomfortable’ conditions, even with the amended summer timings
Great discomfort - Danger of heatstroke
Distinct stress
Everyone feels discomfort
Over 50% uncomfortable
Some people uncomfortable
No discomfort
Air temperature - C
15 20 25 30 35 4540 50
RH 100%
80%
60%
40%
20%
0%
o
Ref G MacMillan, MoW, Bahrain
28 November 2013

Implications for lifecycle asset management
• Extreme climate, and potential poor quality, lead to faster deterioration
• “Imported” codes and guides often come from temperate regions
• High vulnerability requires measures beyond most codes:
1. Design-out vulnerability, where possible
2. Materials selection based on
durability modelling in design
3. Robust construction
specification and management
4. Whole life-cycle view
• Growing recognition of
importance of asset management
Extreme
Environment
Poor as-built
Quality
Special
Measures
CODES
28 November 2013

Concrete durability technologies
• Technologies and experience for achieving long-term durability have
now been available for some time.
• Materials and processes for improving concrete durability are
available in cements, admixtures, steel and electrochemistry.
• Codified approaches have been developed which address durability as
a design procedure including service life prediction models .
28 November 2013

Durability-based design
• At the 3rd Bahrain Conference on Deterioration and
Repair of Concrete in the Arabian Gulf, in 1989
(~25 years ago), the closing panel discussion
concluded:
“the technology all exists for long-term (100-year)
durable reinforced concrete construction in the
Gulf, the issue is implementation”.
'Special' structures
“Structures with extended design lives, i.e. greater
than 30 years, and structures in extreme exposures
require special consideration and may need some
form of enhanced protection.”
“A durability study should be undertaken by
designers leading to a project specific
durability plan”
28 November 2013

Durability by “designing-out” vulnerability
• Piled foundation vulnerable to
deterioration caused saline
ground-water
• Evaporation-driven mechanism
designed-out by waterproofing
• Highly-vulnerable berth design
based on network of deck beams
supported on piles
• Splash-zone vulnerability
designed-out by switching to non-
reinforced mass concrete blocks
Ref: Guide to the design of concrete structures in the Arabian Peninsula
Splash
28 November 2013

“Designing-for” durability
1. Determine
• Required life of facility
• Exposure conditions
• Deterioration mechanisms
2. Identify options and their performance
3. Deterioration models
4. Reliability analysis
2.05m
1.68m MHHW
0.35m MLLW
Submerged zone
Tidal zone
Splash zone
Atmospheric zone
Exposure zones
Effect of Cement Replacement
on Time to Cracking
0
20
40
60
80
100
120
0 10 20 30 40 50 60 70 80
Cover Depth mm
Time(years)
opc
7% microsilica
30% pfa
60% ggbfs
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0 20 40 60 80 100 120 140 160 180 200 220
Time (Years)
FailureProbability(Pf)
BS 8500-1 Specification: Nominal cover 50mm
Hunterston Design: Nominal cover 80mm
20% failure probability
at 100 years
Serviceability Limit State
reached at 62 years
Serviceability Limit State
reached at 170 years
Failure probability v/s time
28 November 2013

chloride, %
vs. depth, mm
Principles of durability modelling
• Surface chloride
• Diffusion co-efficient
• Ageing factor
• Temperature
• Chloride threshold
• Background chloride
Allowable crack-width
Maximum cover
Target service life
Concrete constraints
(e.g. available sources,
structural design)
Requirements for
additional protection
Options and costs of
additional protection
Durability model
Cover tolerance
Concrete options
Minimum cover
Nominal minimum cover
Casting method
Possible
solutions ? N
Y
28 November 2013

Cement Admixture Rebar Surface Electrochem
PC Plasticisers
Carbon Steel
Rebar
Extended
Curing
Chloride
Monitoring
Micro-
silica
Self-
compacting
agents
Non-
reinforced
Design
Controlled
Permeability
Formwork
Corrosion
Monitoring
PFA Water-proofers
Stainless
Steel Rebar
Penetrating
Sealers
Provision for
future CP
GGBFS
Corrosion
Inhibitors
Non-metallic
Rebar
Surface
Coatings
Cathodic
Prevention
Durability “Menu” of possible materials choices
Controlling
penetration
Controlling
corrosion
Legend :
28 November 2013

40km sea-crossing structure with long design life:
durability in design
• “Materials selection for main structural elements shall be based upon
a Durability Strategy Study to demonstrate that proposed materials
are suitable for 120 years service life, without major repair or
replacement, and only normal maintenance.”
• “Accessible components exposed to significant wear or deterioration
shall be designed for demonstrated cost-optimal service life and
replacement, as defined in the Operation and Maintenance Manual.
(e.g. roadway pavement, bearings, lighting, ...).”
construction
methods
protection
options
exposures
Project Name:
Strength grade 25 MPa Diffusion coefficient estimated Est by w/c
Concrete density 2350 kg/m3
Diff Coeff (at 20°C) 1.18E-12 m2/
s
Total cementitious content 350 kg/m3
Age of measured value (yrs)
Binder type (pc, ggbs, pfa, sf ) PC Age Dependant Diffusion Y
Percentage Binder 0 % wt of binder Switch off age dependency at given date Y
Water/binder (w/b) 0.50 Turn off age dependancy at (yrs) 20
Background Chlorides 0.20 % wt of binder
Dca at 35 days 2.10E-11 35
Reinforcement Type Carbon Steel Dca at 20 years 2.91E-12
Bar diameter 10 mm Dca at 20 years 2.91E-12 m2
/s
Age Factor 0.37
Ambient Temperature 35 o
C
Temperature affected Dca Y Surface chloride level 0.60 % cement
Temperature affected threshold Y Adjusted surface chloride level 0.60 % cement
Surface Chloride Level (% wt cem) 0.6
Exposure Condition 3. Cyclic wet/dry Temp & Binder adj threshold (Ct) 0.10 % cement
Carbonation factor considered? Y
Relative Humidity (%) 70
Coating used? No Minimum Chloride Time to
Cover Depth threshold > initiation
(mm) 0.1 % by mass cement plus cracking
Controlled permeability formwork? N
Silane Impregnation N 15 1
Integral Waterproofer N
56
Estimated Values (Temp adjusted)
Reinforcement Details
Exposure Details
Time to Serviceability Limit State (Years) (Deterministic)
Modelling for Chloride Ingress into Concrete
Time to corrosion initiation and cracking
Analysis Type: DETERMINISTIC
Concrete Details Diffusion Coefficient Details
Additional Protective Measures
28 November 2013

Port berths with severe early-age cracking :
neglecting durability in design
• Gravity quay wall constructed from large pre-cast non-reinforced
concrete blocks
• Concrete displaying severe cracking 2-3 years from construction,
confirmed due to Delayed Ettringite Formation (DEF)
• Future damage development modelled
• Potential impact on structural behaviour leads
to loss of stability by overturning or bearing failure
• Key remedial considerations include:
• Maintaining structural stability
• Existing alignment of cranes and berths
• Confidence in existing facilities
during reconstruction
28 November 2013

The next challenge ?
• Effective life-cycle management of critical concrete structures, needs
understanding of the wider implications of technical decisions.
• The next infrastructure challenge is likely to be effective management
of substantial ageing asset portfolios, now 15, 25 or even 35 years old.
• Techniques are needed for understanding how condition assessment and
deterioration prediction inform life-cycle cost and overall business
impact, as a basis for prioritisation, including
• portfolio-level views,
• remedial-policy comparison,
• and operational decision optimisation.
28 November 2013

Service Life
Evolution of reinforced concrete corrosion
CO2, Cl¯
CorrosionofSteelReinforcement
TimeInitiation Phase
Maximum Permissible Corrosion
Propagation Phase
Service Life

Service Life
Effect of Maintenance/Rehabilitation on Service Life
DeteriorationofStructures
Time
Initiation Phase
Maximum Permissible Deterioration
Propagation Phase
No visible damage Visible damage
Proactive
Reactive

Service Life
De Sitter’s Law of Five
DeteriorationofStructures
Time
Initiation Phase
Maximum Permissible Deterioration
Propagation Phase
$25
$1
$5
EquivalentCostforProlongingServiceLife
$ 125
No visible damage Visible damage

Cooling-water basin with premature reinforcement
corrosion: expensive repair at early age
• Cooling water basin in a cooling-tower at major petrochemical plant.
• Basin constructed of pre-cast slabs with liner, elevated on beam and column support
structure. 32m x 220m in plan.
• Severe reinforcement corrosion
due to leakage onto support structure.
• Cathodic protection chosen for :
• Minimised break-out to beams/columns = speed
• Embedment in replacement slab = longevity
• Remedial programme included constructing
divider wall to avoid loss of availability
28 November 2013

Regional infrastructure timeline
1970s 1980s 1990s 2000s 2010s 2020s
early
construction
early
remedials
boom
5 15 25 35 45
potential
ages (years) of
infrastructure
in the region
5 15 25 35
5 15 25
5 15
recent
downturn
??
28 November 2013

How do you spend your maintenance budget?
November 2013

Understanding risk-exposure
• Hazard : operational impact of infrastructure
• Likelihood (L)
• Increases with time for deteriorating assets
• Linkage to business cycle
• Consequences (C)
• Direct cost (often premium cost e.g. out of hours)
• Indirect cost (management)
• Penalty costs (e.g. highway possession)
• Cost of lost availability (e.g. lost production)
• Safety
• Monetised costs of accidents
• Consequential costs of accidents
• Environmental
• Reputational
Asset Name MSCP 1
Purpose Short stay multi-storey car park (public)
Age Commissioned 1967 (Extended 1976)
How to Use:
Likelihood Ranking: 1=Improbable (<10%); 2=Unlikely(10-30%); 3=Less Than Likely(30-50%); 4=More Than Likely(50-80%); 5=Probable(>80%) fill in yellow to describe
fill in brown to describe URGENT
Consequence Ranking: 1=Minor; 2=Moderate; 3=Significant; 4=Substantial; 5=Grave fill in blue to describe progression
Consequence Category: pick from matrix for (5x likelihoods) and (max consequence)
Safety 1=Minor injuries, 2=Major injuries, 3=Single fatality, 4=Multiple fatalities (eg up to 100), 5=Multiple fatalities(eg over 100)
Security 1=Minor breach of regulations, 2=Reportable breach of regulations, 3=Prosecution, 4=Short airport closure, 5=Long airport closure
Environment 1=Short term local damage, 2=Short term regional damage, 3=Long term local damage, 4=Long term widespread damage, 5=Widespread permanent damage
Financial (based on EBIT) 1=<£1m, 2=>£1-25m<, 3=>£25-50m<, 4=>£50-100m<, 5=>£100m
Reputation & Legal 1=Improvement notice, minor local reputation damage, 2= Prohibition notice, major local reputation damage, 3= Prosecution with fine, national adverse media coverage, 4= Directors charged
with corporate killings, fraud, etc. International adverse media coverage, short term, 5= Directors convicted of corporate killing, fraud, etc. International adverse media coverage - >1year.
Control Rating:
1. Excessive Controls exceed the level required to manage the risk
2. Optimal Controls are reasonably practicable, comprehensive and commensurate with the risk. All controls are evidenced as working as intended
3. Adequate Some shortfall in level of controls but these do not materially affect the level of residual risk
4. Inadequate Weaknesses and inefficiency in controls do not treat the risk as intended. Remedial action required
<6mths
>6/<12mths
>1yr/<3yrs
Maximum
1
Widespread distress or
deformation of MSCP
structure potentially leading
to collapse (structural
failure).
Deterioration of
waterproofing/floor coatings and
structural concrete topping
resulting in reduced capacity
and increased risk of corrosion.
Joint leaks and blocked
drainage allowing water ingress
and accelerated corrosion.
1 1 1 1 2 4 1 2 4 4 4
Meetings of 3 & 14/12/10, and site
visits 14 & 17/12/10. Jacobs Report
No. J24172A8/508/061/01.1 &
J24172ME/506/001.1.
Repair structural topping and floor
coatings to prevent water ingress.
Repair/replace joints to prevent leaks
and reduce risk of corrosion.
3
Car park closure and major structural
propping. Road closures in the vicinity of
Terminal 1.
A A A A A
2
Localised distress or
deformation of multi storey
car park structure (reduced
load capacity).
Deterioration of
Overloading from temporary
office building (NW of building).
water ingress and corrosion to
cantilever sections.
1 1 2 3 4 3 1 2 2 3 3
No. J24172A8/508/061/01.1 &
J24172ME/506/001.1.
Repair structural topping and floor
coatings to prevent water ingress.
3
Car park closure and major structural
propping. G G A A R
3
Members of the public
injured by concrete spalling
(particularly adjacent to
joints)
Deterioration of
2 2 3 4 5 3 1 2 2 3 3
No. J24172A8/508/061/01.1 &
J24172ME/506/001.1.
Repair/replace defective
waterproofing.
3
Localised car park closure and structural
propping. A A A R R
4
Spalling concrete damages
EDF electrical equipment in
basement.
Deterioration of
2 2 3 4 5 2 1 2 2 3 4
Jacobs Report No.
J24172A8/508/061/01.1 &
J24172ME/506/001.1.
Repair/replace defective
waterproofing.
NOTE: Access to the basements was
not available as part of Jacobs
inspections. Comments are
precautionary.
3
Electric failure resulting short term airport
closure. A A R R R
5
Public injury due to trip
hazards
Isolated areas of debonded
decorative surfacing.
Deterioration of structural
concrete topping particularly
adjacent to joints.
3 3 4 5 5 1 1 1 1 1 1
No. J24172A8/508/061/01.1 &
J24172ME/506/001.1.
Carry out concrete repairs to
structural topping to remove trips.
Replace joints and maintain drainage
to minimise water ingress and risk of
corrosion.
3 Localised closure of affected areas. G G A A R
6
Collisions between vehicles
and pedestrians
Isolated areas of worn and/or
debonded decorative surfacing.
Deterioration of structural
concrete topping particularly
adjacent to joints.Ponding water
resulting in ice. Poor
lighting/dark atmosphere.
2 2 2 2 2 3 1 1 1 3 3
No. J24172A8/508/061/01.1 &
J24172ME/506/001.1.
Carry out concrete repairs to
structural topping to remove trips.
Replace joints and maintain drainage
to minimise water ingress and risk of
corrosion. Repair/replace defective
waterproofing.
3 Localised closure of affected areas. A A A A A
7
Failure of canopies at Level
6
Water ingress resulting in
internal corrosion of steel tubes.
Possibility of overstressing
during high winds.
2 2 3 4 4 3 1 2 1 3 3
Site visits 14 & 17/12/10. Jacobs
Report No. J24172A8/508/061/01.1 &
J24172ME/506/001.1.
Carry out structural inspection to
assess extend of internal corrosion.
Where necessary strengthen or grout
tubes as approriate.
3 Localised closure of affected areas. G G A R R
Financial
Reputation
Safety
>8yrs
Evidence
(i.e. source reference)
Risk Assessment vs
time, using RAG
matrix
<6mths
>6/<12mths
>3yrs/<8yrs
>1yr/<3yrs
ControlRating
Actions / Controls
at 0-6 months
(i.e. what should be done
urgently, if anything)
Actions / Controls
at maximum likelihood
(i.e. what would have to be done
to prevent the worst form of this
UNMITIGATED hazard)
Hazardref
Security
Environment
>3yrs/<8yrs
Hazard
(i.e. what could
happen if no
action/control taken)
Root Cause
(i.e. why it would
happen)
>8yrs
likelihood
vs time
consequence
5
A R R R R
4
A A R R R
3
G A A R R
2
G G A A R
1
G G G A R
1 2 3 4 5
Likelihood
Consequence
Likelihood Consequence
28 November 2013

Optimising timing based on risk
• Lost revenue from
lost availability
• Direct and management cost
of interventions
• Reputation damage
• Accidents
• Environmental damageMaintenance cycle (years)
Totalcost(AED/year)
Optimised timing
Cost/year of maintenance
(reduces as becomes less frequent)
Total risk cost /year (increases as
hazard becomes more likely)
$
RISK
CONDITION
28 November 2013

Budget-setting down to a risk-level
• Priority order based on task risk cost
• Budget = cumulative task cost
Result =
1.funding down to a risk level
2.visible impact of budget setting
Maintenance
tasks
Task risk
cost
Cumul
risk cost
Task
cost
Cumul
task cost
task 2000 2000 1000 1000
task 1800 3800 500 1500
task 1500 5300 800 2300
task 1300 6600 3000 5300
task 1000 7600 800 6100
task 950 8550 300 6400
task 750 9300 1400 7800
task 300 9600 700 8500
task 200 9800 450 8950
task 100 9900 300 9250
$ risk
risk level at
available budget
Value = ${risk mitigated} / ${cost}
28 November 2013

Life-cycle cost assessment
1. Portfolio cost of ownership
2. Maintenance policy-testing
3. Operational decision-making
• BS ISO 15686 – Service Life Planning
• Built up from components to the whole.
• Performance of components
under expected conditions
• Likely failure modes
• Causes of loss of serviceability
• Risk of premature failure
• Effects on service life.
£0
£50,000,000
£100,000,000
£150,000,000
£200,000,000
£250,000,000
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30
WLC elements v/s time
28 November 2013

1: Overall portfolio level cost of ownership
• Consistent treatment of multiple asset types
• Overall cost of ownership:
• Asset “creation” costs
• Corrective maintenance at transfer
• Major interventions
• O&M
• Benefits:
• Informs expenditure requirements
• Service charge tariffs
• Asset values and depreciation
WLC elements v/s time
NAV forecast
28 November 2013

2: Maintenance policy testing for lowest WLC
• Population condition and intervention
modelling.
• Benefits:
• Compare management policies, e.g.
• Periodic major repairs
• Little and often
• Justify budget submissions
Year 1 : No Spend Year 5 : AED 30M/yr Year 5 : No Spend Year 5 AED 70M/yr
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
1
6
11
16
21
26
31
36
41
46
51
56
61
66
71
76
81
86
91
96
Year
LikelihoodofConditionState
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
% Component Condition in Poor % Component Condition in Marginal % Component Condition in Good
% Comparator in Poor % Comparator in Good
£0k
£200k
£400k
£600k
£800k
£1,000k
£1,200k
£1,400k
£1,600k
£1,800k
0 20 40 60 80 100
Year
CumulativeNPV
£k
£200k
£400k
£600k
£800k
£1,000k
£1,200k
NominalExpenditurep.a.
Cash Flow Baseline Comparator
Expenditure & NPV over life
Effectofinvestment
profileoncondition
28 November 2013

3: Operational decision-making
• Industry R&D project to produce:
• Process & methods guidance
• Decision-support tools
• Case studies & templates
• Tool-kit for optimising:
• managing aging degrading assets,
• obsolescence, renewals and refurbishments,
• inspection & maintenance timings.
• Benefits:
• All pilot studies revealed >£700k/year potential improvements; one up to €25M
• Generic approach is effective, and uses existing tacit knowledge to help technical people
make robust, transparent & auditable WLCC decisions and business cases
e.g. Moving from 12 to 24 mths inspection interval
saved £37,000/mth (= £438,000/yr).
cost of delay
cost of caution
28 November 2013

Putting it all together for the challenges ahead…
• Plan for durability
• Use condition assessment and deterioration prediction tools
• Understand your risk-exposure
• Set maintenance budgets to the appropriate risk level
• Optimize timing of maintenance intervention
• Use whole life cycle cost assessment
• Overall portfolio cost of ownership
• Test maintenance policies for lowest WLCC
• Optimize operational decision making
28 November 2013

32 Concrete Maintenance Workshop - Faiz M Khan
Thank you
Faiz M Khan
Faiz.Khan@ch2m.com
+971-50-9295278
P.O.Box 360, Dubai, UAE
1 October 2012

Challenges in managing structural asset portfolios in the Middle East

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