Pune Lecture 9-9-2014 - Indian Society of Structural Engineers Pune

Report
Recent Innovations in Concrete &
Foundations Leading Sustainable Growth
By
Dr. N V Nayak
Principal Advisor, Gammon India Limited
Chairman, Geocon International Pvt. Ltd
The First Memorial Lecture
In Memory of Late Prof. Y.S. Sane
9TH Sep
2014
Organizers : ISSE, Pune District Center
I.
Concrete
1.0 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
Annual India’s Concrete consumption
Target without increased cement
production
World Annual Cement Production
Consumption (in 2013)
China’s Annual Cement Production
India’s Annual Cement Production
: 20000 Mt
: 1000t Mt
: 4000 Mt
(4 Times)
:4000Mt
: 2350 Mt
(58.7%)
: 280 Mt
(6.7%)
India
6.7%
China
58.7 %
3.0 Emission of CO2
1 t of Cement Production releases
0.9 t of CO2
1 t of Cement consumed in
concrete absorbs while hardening
(-) 0.4 t of CO2
Therefore, net 1 t of cement produced
and releases consumed in concrete
emits
0.5 t of CO2
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 Production
6 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) = 20000t
o 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
AIM Design for Life
=
= 50 - 60 years 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 Corrosion
Solution
SCM Maximum Permissible
limit
GGBS in marine conditions
preferred.
Fly ash & not GGBS in Roads
In General 70% replacement
GGBS + fly ash together
4.3.2 Carbonation Corrosion
Solution
• Fly ash preferred
• If
GGBS
used,
Restrict to 50%; for
higher percentage
plastering is to be
adopted.
4.3.3 Damp patches on the surface of a
reinforced concrete arch affected by ASR
Solution
High permissible % of SCM
like
• fly ash (25 to 50%)
• GGBS (50 to 70%)
• Metakaoline (10 to 20%)
• Silica Fume (5 to 10%)
4.3.4 Sulphate Attack
Solution
High percentage of
• GGBS – 1st preference
• Fly ash – 2nd
preference
Not to be preferred
• Silica Fume
• Metakaoline
4.3.5 Pile Concrete in Industrial
Environment
√ Normally
we determine pH, Chloride
Sulphate in ground Water and Subsoil;
and
√ 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
Fly ash
% Addition Resistance to On
On
On
On
with respect Alkali-Silica
Carbonation Chloride
Sulphate
Industrial
to
Reaction/Exp Resistance Resistance Resistance Waste
ansion
Total
Cementitiou
s content
10% to 25%
Good to Very Moderate
Good
Good
Good
26% to 50%
Excellent
Moderate
Excellent
Good
50%
Very Good
Moderate
Very Good
Very Good
b) Better
than
1(a)
Very Good
50 to 70%
Excellent
Poor
Excellent
Excellent
Excellent
Silica Fume
5 to 10%
Excellent
Moderate
Very Good
Moderate
-
Metakaoline
10 to 20%
Excellent
Moderate
Very Good
Moderate
-
GGBS
a) Slightly
better
than
OPC
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%)
Fly ash (>26%), GGBS (>50%)
Chloride Corrosion
Silica Fume, Metakaoline
Fly ash (≤25%), GGBS (≤50%)
GGBS (>50%)
Sulphate Resistance
Fly ash
Silica Fume, Metakaoline
GGBS (> 50%)
Industrial Waste
GGBS (<50%)
Fly ash (<50%)
4.3.6 CASUAL APPROACH
Innumerable cases
Densely Reinforced Beam-Column Junction
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
5.1 Removal of Concrete above cutoff level
Chipping of concrete by Jack
Hammer by Wedge Method –
Widely adopted
Taets Pile Breaker
5.1 Removal of Concrete above cutoff level
Performance of Taets
Taets Pile breaker – Costly but
time effective and quality suspect
Consequences
Micro 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
Scooping Tool
Methodology
•
Remove Concrete soon
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
reduction
after
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 Provide
Consequences ??????
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 29112010”)
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..)
N
PPR Value
Remarks
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
RatioPPR”
has
been
developed.
O PPR Reflects Energy in
tm required to Advance
Borehole of 1m2 cross
section by 1 cm
Value
of SPT
(tm/m2/cm)
50
37.35
100
74.70
150
112.05
200
149.40
250
186.75
300
224.10
350
261.45
400
298.80
For N Values in
between, Linear
Extrapolation will
be adopted
This approach can
be adopted up to N
Value of 400
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…
Curve (a) – IS 2911 Part 4 – 1985 @ 1.5 times
design load
b) Curve (b) - IS 2911 Part 4 – 2013 @ 1.5 times
design load
c) Curve (c ) - 10% of Pile dia @ ultimate load
d) Curve (d) – 2% of pile dia @ 1.5 times design
load
e) Curve (e ) - 3% of pile dia @ 1.5 times design
load
a)
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”

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