Recent Innovations in Concrete & Foundations Leading Growth

By

Dr. N V NayakPrincipal Advisor, Gammon India Limited

Chairman, Geocon International Pvt. Ltd

Organizers : ISSE, Pune District Center

Sustainable

The First Memorial Lecture In Memory of Late Prof. Y.S. Sane

9TH Sep 2014

I. Concrete1.0 Preamble

“Worldwide levels of carbon dioxide, have reached their highest level in 3 million years, US Scientists have said”.

“Times of India, Mumbai, June 2013”

“In 1.8bn years Earth Will Become Too Hot As Seas Will Evaporate”

“Times of India, Mumbai, 20th September 2013”

World Average Temperature will rise by at least 4°C by the year 2100 and at least by 8°C by 2200.

“Times of India, Mumbai, 21st October 2013”

“East Himalayan Forests Turning Brown”

“Times of India, Mumbai, 2nd January 2014”

We have to reverse this trend, for our survival for the future.

How?

&

Without affecting the Growth/Development by

Sustainable Development;

Why Discuss “Concrete” for Sustainable Development?

o Concrete is Most Widely used construction Material only next to water.

o It Generally produces Carbon Dioxide (CO2).

2.0 Sustainable Development

Annual World Concrete Consumption : 20000 Mt

Annual India’s Concrete consumption : 1000t Mt

Target without increased cement : 4000 Mt

production (4 Times)

World Annual Cement Production :4000Mt Consumption (in 2013)

China’s Annual Cement Production : 2350 Mt

(58.7%)

India’s Annual Cement Production : 280 Mt

(6.7%)

India 6.7%

China58.7 %

3.0 Emission of CO2

1 t of Cement Production releases 0.9 t of CO2

1 t of Cement consumed in (-) 0.4 t of CO2

concrete absorbs while hardening

Therefore, net 1 t of cement produced

and releases consumed in concrete 0.5 t of CO2

emits

Hence we in India release 0.34 Mt of CO2

producing & Consuming 280 Mt of Cement Annually / day

Concrete Production for Growth Must

How to make it Sustainable

4.0 Sustainable Concrete Production6 Steps to be followed

(*)Make Compulsory use of Secondary Cementing Material (SCM)

(Saving Roughly 60-70%)

Produce more Durable Concrete

(Increased Life Almost Double)

(*) Use Higher Strength Concrete

(Saving roughly 30%).

(*)Use Higher Size of Aggregate (MSA) in Concrete

(Saving roughly 10%).

(*)Use optimum Cement Content in Concrete.

Encourage use of “Carbon Negative Cement”.

With (*) alone, we can produce ≈ 4 times the concrete for given amount of cement manufactured.

4.1 Main Secondary Cementing Materials

o Fly Ash (FA)

–Annual Production – 200 Mt;

o Ground Granulated Blast Furnace Slag (GGBS);

- Annual Production : 90 Mt

o Metakaoline (MK);

– Annual Production : 7000 t ( Complete Export……..)

o Rice Husk Ash (RHA);

o Micro-silica (MS);

o Ultrafine Fly Ash & Ultrafine GGBS (UFFA; UFS, Alcofine) (Recent Innovations)o Annual Production : (5000 t + 15000 t) = 20000to Annual Export : (2000 t + 4000 t) = 6000 t… (30%)

4.2 Codal Provisions

Author’s Recommendation

Use fly Ash up to = 50%

Use 70% in combination with Fly Ash + GGBS, or 85% GGBS Alone. Why ?

Avoid Micro Silica (MS) ; Why ?(explained later)

Substitute MS by UFS/Alccofine, Ultrafine Fly Ash. Why ?

4.3 Durable Concrete

Present Practice, Design = 50 - 60 years Life

AIM Design for Life = 100 - 125 Years

Possible

Increased Life - Reduced Concrete Requirement

- Reduced Cement Requirement

To make Durable Concrete, Concrete to Resist certain Aggressive Environment (Mainly 6)

1.0 Chloride corrosion

2.0 Carbonation corrosion

3.0 Alkali Silica Reaction

4.0 Sulphate attack

5.0 Industrial waste

6.0 Casual approach

Why ? (See photos below)

Solution

Common to all

Low

w/b ratio ≈ 0.3

To make Durable Concrete, Concrete to Resist certain Aggressive Environment

4.3.1 Chloride CorrosionSolution

SCM Maximum Permissible limit

GGBS in marine conditions preferred.

Fly ash & not GGBS in Roads

In General 70% replacement GGBS + fly ash together

Solution• Fly ash preferred

• If GGBS used, Restrict to 50%; for higher percentage plastering is to be adopted.

4.3.2 Carbonation Corrosion

Solution

High permissible % of SCM like • fly ash (25 to 50%)• GGBS (50 to 70%)• Metakaoline (10 to

20%)• Silica Fume (5 to

10%)

4.3.3 Damp patches on the surface of a reinforced concrete arch affected by ASR

4.3.4 Sulphate Attack

SolutionHigh percentage of • GGBS – 1st

preference• Fly ash – 2nd

preferenceNot to be preferred• Silica Fume• Metakaoline

4.3.5 Pile Concrete in Industrial Environment

√ Normally we determine pH, Chloride and Sulphate in ground Water and Subsoil;

√ Many other factors of ground water affect performance of concrete;

√ These are of importance in Industrialized Areas.

√ Why? [See Figures]

Influence of Industrial Wastes on Structures

Solution:

GGBS : > 50% (1st Preference)

: < 50% (2nd Preference)

Fly Ash : ≈ 50% (3rd Preference)

Summary of effectiveness of SCM on concrete

Type of SCM

% Addition with respect to

Total Cementitious content

Resistance to Alkali-Silica Reaction/Expansion

On Carbonation Resistance

On Chloride Resistance

On Sulphate Resistance

On Industrial Waste

Fly ash 10% to 25%

 

 

26% to 50%

Good to Very Good

 

Excellent

Moderate

 

 

Moderate

Good

 

 

Excellent

Good

 

 

Good

a) Slightly better than OPC

b) Better than 1(a)

GGBS 50%

50 to 70%

Very Good

Excellent

Moderate

Poor

Very Good

Excellent

Very Good

Excellent

Very Good

ExcellentSilica Fume

5 to 10% Excellent Moderate Very Good

Moderate -

Metakaoline

10 to 20% Excellent Moderate Very Good

Moderate -

Category Preferential order of Various SCM

Alkali-Silica Reaction

Fly ash (High%), GGBS (high%), Silica Fume, Metakaoline

Carbonation Fly ash, GGBS (<50%), Silica Fume, Metakaoline

GGBS (>50%)

Chloride Corrosion

Fly ash (>26%), GGBS (>50%)

Silica Fume, Metakaoline

Fly ash (≤25%), GGBS (≤50%)

Sulphate Resistance

GGBS (>50%)

Fly ash

Silica Fume, Metakaoline

Industrial WasteGGBS (> 50%)

GGBS (<50%)

Fly ash (<50%)

Densely Reinforced Beam-Column Junction

4.3.6 CASUAL APPROACH Innumerable cases

Solution

Self Compacting Concrete

Benefits of Ultrafine Slag and Fly ash Better Workability & Retention Period

Better Pumpability

Early Strength Gain

Reduced Drying Shrinkage

Better Sulphate Resistance

Better Pore Size and Particle Packing (Reduced permeability)

Better Resistance to Industrial Waste

Reduced Cost

Recent & Future Developments of Concrete Ultrafine Slag & Ultrafine Fly ash - Need Fast

Implementation

Self curing concrete - High Priority

Dry mixing of concrete in Batching plant - High Priority

Industry waste as aggregate Bendable concrete Self cleaning concrete Self healing concrete (Bacterial concrete) Carbon negative cement controlled permeability formwork

5.0 Foundations : Pile Foundations - Bored Cast-in-situ

Preamble

Simple innovations are referred here which will have great effect on durability and sustainability

Taets Pile Breaker

5.1 Removal of Concrete above cutoff level

Chipping of concrete by Jack Hammer by Wedge Method – Widely adopted

5.1 Removal of Concrete above cutoff level

Performance of Taets

Taets Pile breaker – Costly but time effective and quality suspect

ConsequencesMicro Cracks getting developed in Piles below cutoff level and chances of endangering its performance.• Measures for

Improved Performance ?????

5.1Removal of Green Concrete above pile cut-off

Developed by Speaker and adopted in IRC 78 – 2011

Methodology• Remove Concrete soon after

completion of Pile Concrete;

• Generally removed manually by Tumbler for depth up to 0.5m below ground;

• Special Tool is used for deeper depth (See Figure );

• After removal, Vibrate Concrete using Rammer (Fig in next slide);

• In absence of Ramming/Vibration, Air voids will be present in concrete which will result in strength reductionScooping Tool

5.2 Removal of Green Concrete above pile cut-off

Rammer for Vibration of Concrete after scooping

Compressive Strength Results

5.3 L Bend to Pile Reinforcement Cage

Theoretically Not Required Except in some special cases.

Majority Still ProvideConsequences ??????

L Bend to Pile Reinforcement Cage (Contd..)

Reasons:O Proper flushing may

not be possible;O Concrete Flow also

may not be proper. (see Adjacent

pic)

Recommendations :

Avoid L Bend in Main Reinforcement steel at bottom of Pile, unless mandated

Sand, Not

Concrete

5.4 Socketing of Pile in Weathered/Soft Rock

• Many Practices are adopted to decide Socket Length;• Speaker has been Adopting “Cole-Stroud Approach

Based on N Values of SPT” since 1974. (Now adopted by Bureau ofIndian Standards “IS 2911- 2010”)

Main Point to note

FS = 3 in Friction and also in End Bearing. Thorough Investigation needed

Was adopted for Zuari- Mandovi bridges for KRCL, Goa India.

(see Adjacent Figure).

Socketing of Pile in Weathered / Soft Rock (Contd..)

O Some Insist of doing “SPT” Test. This is not desirable from time and cost consideration.

O To overcome this problem, quality control concept involving “Pile Penetration Ratio-PPR” has been developed.

O PPR Reflects Energy in tm required to Advance Borehole of 1m2 cross section by 1 cm

N Value of SPT

PPR Value (tm/m2/cm)

Remarks

50 37.35

For N Values in between, Linear Extrapolation will be adopted

100 74.70

150 112.05

200 149.40

250 186.75

This approach can be adopted up to N Value of 400300 224.1

0

350 261.45

400 298.80

5.5 .Torque Meters on Control Panel

Torque Meters Force Meter

5.6 Convert Marine Piling to Land Piling

In Konkan Railway Project, out of 15 marine jobs, 13 jobs were converted fully to land piling by AFCONS

4.5 Km long Bridge on Godavari River converted into Land Piling by Gammon,

Max Depth of water ~ 14m (See Adjacent pic)

Advantages : Substantial Time and Cost Reduction

5.7 Settlement Criteria for Load Test

Settlement Criteria For Load Test Cont’d…a) Curve (a) – IS 2911 Part 4 – 1985 @ 1.5

times design loadb) Curve (b) - IS 2911 Part 4 – 2013 @ 1.5

times design loadc) Curve (c ) - 10% of Pile dia @ ultimate

loadd) Curve (d) – 2% of pile dia @ 1.5 times

design loade) Curve (e ) - 3% of pile dia @ 1.5 times

design load

5.8 Capacity of Under ream Piles

IS 2911 – Part 3 – 1980 –

Incorrect Recommendation.

Why?

5.9 MSA in Foundations & Substructures

Recommend – 40mm MSA

Save 10% in cementitious material

5.10 Highly Innovative Indian Design

Zuari Bridge on Konkan Railway

Novel Concept Adopted for the First Time in India

o Only 14 Well Foundations on entire Konkan Railway Project (over 100 bridges)

o Caissons / Wells were pneumatically sunk.

o Founding depth of one caisson was 30 m below water level.

- Workers could hardly work for ½ hour.

Hence Novel Idea founding caisson on piles was adopted for the first time in India

(See Pic in Next Slide)

Details of Caisson Resting on Piles

Way Forward

Determined Approach by all of us to follow “Sustainable Growth Guidelines”

Saving in Piling – Minimum 25% over the present practice

Saving in Concrete – Minimum 10% over the present practice

Thank you

“Jai Hind”

“Jai Bharat (India)”

“Jai Maharashtra”