Climate change &

concrete infrastructure

Dr. Sree Nanukuttan & Prof. Muhammed

Basheer

Layout of presentation

• Deterioration of structures & the role of exposure environment

• Economics of infrastructure management • Performance of built infrastructure in

changing climate – example carbonation • Concluding remarks & further research

Why do structures deteriorate?

Protected by gamma ferric oxide layer pH~13 ; Chloride ions negligible

H2O

CO2

Cl-

O2

Steel in concrete

Exposure Environment

Inside Concrete

Concrete Cover

Life cycle thinking… co

st pr

e-co

nstr

uctio

n

construction

Inspection/ maintenance Case 1 - Ideal

Case 2 - Typical

pre-

cons

truc

tion

construction Inspection/ maintenance

Life Cycle Costing

Cost analysis for a 50 year period. Future costs are all brought to present value

Case

1

Case

2

Role of environmental loading

Zone A = Mild; Zone B = Moderate; Zone C = Harsh)

Condition rating of structures and the role of exposure environment

Cond

ition

Rat

ing

Case 1

Case 2

Rating 3-4

Rating 2

Causes of deterioration of structures

33%

5%

17%

4% 10%

9%

10% 5% 7%

Chlorides (External) Chlorides (Internal) Carbonation Chemical Abrasion Alkali-Aggregate Reaction Freeze-Thaw Shrinkage & Settlement Other

Carbonation

Carbonation of Concrete

=

CO2 Cement matrix Calcium hydroxides + others

Carbonates

•Atmospheric Concentration •Diffusion & Binding •Relative Humidity & Temperature

•Ionic concentrations •Rate of hydration •Construction related

Positives and Negatives of Carbonation

• Damages • Positives Densification of concrete & Carbon capture Absorption of CO2 over the life time of concrete ~ 30kg/m3

Climatic variables - Temperature

Climatic variables - Temperature Current temperature cycle

Future temperature cycle

Affects the diffusion process Affects the binding capacity Brings in other deterioration factors

Climatic variables – CO2 concentration

CO2 Increase - From 1962 – 1971 0.89ppm annual increase - From 2002 – 2011 2.07ppm annual increase

Climatic variables – others

• Relative humidity • Prolonged summers & winters • Rising sea level/salinity/Pressure/Wind • Micro climates

Effect of the increase in CO2 concentration

0

20

40

60

80

100

120

140

0 50 100 150Tim

e to C

orro

sion

Initi

atio

n (ye

ars)

Carbonation Depth (mm)

2000 Average Global CO2 concentration2010 Average Global CO2 concentration2020 Predicted Global CO2 concentration2040 Predicted Global CO2 concentration2060 Predicted Global CO2 concentration2080 Predicted Global CO2 concentration2100 Predicted Global CO2 concentration2050 Predicted Global CO2 concentration

Normal Portland cement concrete, 0.50 w/b, Exposure Class XC3

Increase in CO2 concentration Prediction based on370ppm 573ppm

CEM I Concrete

Effect of climatic variations – CO2 concentration & temperature

CEM II B/S Concrete

Current climate (394ppm & 14˚C) Future climate (600ppm & 19˚C)

Is current specification satisfactory? Graph showing how the concrete mixes performed following the guidelines in

BS8500 for intended working life of 50 years - Current Conditions

05

101520253035404550

0 10 20 30 40 50

Time (years)

Dep

th o

f Car

bo

nat

ion

(mm

) OPC

OPC+35%GGBS

OPC+65%GGBS

OPC+35%PFA

Recommended cover fromBS8500

0.6w/b concrete Current climate (394ppm, 10˚C) 50 years

Types of cement

Graph showing how the concrete mixes performed following the guidelines in BS8500 for intended working life of 100 years- Current Conditions

0

10

20

30

40

50

60

70

0 20 40 60 80 100

Time (years)

Dep

th o

f Car

bo

nat

ion

(mm

) OPC

OPC+35%GGBS

OPC+65%GGBS

OPC+35%PFA

Recommended cover fromBS8500

0.6w/b concrete Current climate (394ppm, 10˚C) 100 years

Is current specification satisfactory?

Types of cement

Graph showing how the concrete mixes performed following the guidelines in BS8500 for intended working life of 50 years using Climate Projections

0

10

20

30

40

50

60

0 10 20 30 40 50

Time (years)

Dep

th o

f Car

bo

nat

ion

(mm

) OPC

OPC+35%GGBS

OPC+65%GGBS

OPC+35%PFA

Recommended cover fromBS8500

0.6w/b concrete Future climate (500ppm, 11.5˚C) 50 years

Is current specification satisfactory?

Types of cement

Graph showing how the concrete mixes performed following the guidelines in BS8500 for intended service life of 100 years using Climate Projections

01020

30405060

7080

0 20 40 60 80 100

Time (years)

Dep

th o

f Car

bo

nat

ion

(mm

)

OPC

OPC+35%GGBS

OPC+65%GGBS

OPC+35%PFA

Recommended cover fromBS8500

0.6w/b concrete Future climate (500ppm, 11.5˚C) 100 years

Is current specification satisfactory?

Types of cement

Concluding remarks Climate change will have a significant effect on

the carbonation process and therefore this needs to be taken into consideration while designing/specifying new structures. More money will need to be spend

maintaining existing structures subjected to carbonation. Other environment related loading could

aggravate the concrete deterioration resulting in significant drain on the economy.

On going research

33%

5%

17%

4% 10%

9%

10%

5% 7%

Chlorides (External) Chlorides (Internal) Carbonation Chemical Abrasion Alkali-Aggregate Reaction Freeze-Thaw Shrinkage & Settlement Other

On going research Developing exposure locations across the world with the help of research partners Highlands, Scotland Donegal Coast, Ireland Lisboa, Portugal St. Nazaire, France Hangzhou Bay Bridge, China

Quantifying the impact of climate change on infrastructure: Performance Monitoring and Cost/Performance predictions

domestic buildings and large civil infrastructures Developing more adaptive maintenance strategies for asset managers