How to Ensure Quality, Durability and Lifetime Expectations of Modern Infrastructure

Projects - Contractor’s perspective

Mr. Giridhar Rajagopalan Executive Director – Technical

CONCRETE SHOW INDIA 2018 24th May 2018

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Introduction

• Structures built in the olden times have stood the test of times very successfully showing remarkable durability.

Hadrian's Pantheon in Rome is an example of Roman concrete construction. 126 AD

The multiple arches of the Pont du Gard, in Roman Gaul. (300AD)

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Introduction

• Modern structures though built with best technology and systems tend to deteriorate much faster than anticipated and many times do not service the intended service life

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Introduction

• Deterioration of structures once abandoned is brutal and fast

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Where is the difference?

• Built with stone – a stable material • Use of pozzolanic mortars – dense &

impermeable

• Concrete and reinforcement reacts with environment causing quicker deterioration

• Superior workmanship and quality control was more a culture then against a contractual requirement of today

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Introspection to make durable structure

We did it in the past, we can do it again …

• Technical sustainability

• High durability

• Sustainable and green building

• Life cycle cost

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Technical sustainability

Increase in traffic loads grossly underestimated

Assessing impact of environmental exposure conditions

Correct material specification - Performance based specifications instead of prescription based specification

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Concrete durability

Liquids & gases containing Chlorides, sulphates and CO2

Durability Impermeability

Discontinuous capillary pores Dense impermeable concrete

• Mineral admixtures • Lower w/c ratio • Compaction • Curing • Improved workmanship

Maintaining proper cover

Protective coatings

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Concrete crack width

• Estimating correct crack width (consider future traffic loads) • Maintain permissible cover in field • Use good quality cover blocks

If cover increases beyond

permissible, crack width also

increases proportionately

Design cover

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Curing of concrete

Improper water curing can lead to shrinkage cracks

• Water curing is the most effective method, but is many times practically difficult to achieve, especially for vertical surfaces

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Curing of concrete

• Proper application of curing compound will ensure at least 85% curing efficiency which is better than erratic water curing

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Better process control

• Precast technology

• Controlled production

• Improved quality control

• Improved durability

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Sustainability & green building

• Use mineral admixtures

• increased durability & service life

• Improved sustainability

• Reduced carbon footprint

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Life cycle cost

• Look at Life Cycle Cost of project instead of initial cost

• Propose periodic maintenance of structure to enhance the service life

• Periodically assess changes in loading and environmental conditions and suggest change in maintenance plan

• Be proactive rather than reactive

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Improving processes

• Impart training

• Standardise work processes

• Improve supervision

• Improve curing practices

• Conduct root cause analysis for continual improvements

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Improving durability of steel structures

• Proper selection of grade of steel based on fatigue and environmental exposure

• Proper selection of protective paints to improve corrosion resistance

• Providing sacrificial thickness for countering corrosion

• Proper selection of section to avoid accumulation of water and dust

• Design for maximum possible length to minimise welded / bolted joints

• Regular maintenance

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Improving durability of steel structures

In operation since 1943

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Thank you