IITM –IITB-ICI Workshop on
Achieving Durable Concrete Construction Through Performance Testing
(Feb. 2014)
Concrete Durability:
Industry Perspective*
Vijay Kulkarni
Principal Consultant, Ready-Mixed Concrete Manufacturers’
Association (RMCMA)
Former President, Indian Concrete Institute (ICI)
Former Editor, The Indian Concrete Journal (ICJ)
* Views expressed are not necessarily those of RMCMA or ICI
Broad Outline
• Concrete Industry Scenario
• Role of Production Control System influencing
durability
• Recent up-gradation of Production Control Criteria
• Properties of ingredients affecting durability
• Some Live examples of customer-specified mixes
• Use of SCMs: Code-specified Limitations
• Recent changes in IRST and IRC Standard
specifications
• Laboratory Data on RCPT & Strength
• Conclusion
• Future…
Vestige of Recent Past
Courtesy: Mahesh Tendulkar
Typical Modern RMC Plant
Cement/SCM Silos
Aggregate Conveyor
Twin-Shaft Mixer
Aggregate Bins
1st Phase of Development
• Establishment of
RMC facilities in
metropolitan
centres
Delhi
Kolkata
Mumbai
Hyderabad
Bangalore
Chennai
2nd Phase of Development
56 Major Cities
•
•• •
••
•
••
•
•• • •
•
••• • • •
• • •
•
• ••
• •
•• •
•
•
••
1 Amritsar
2 Ahmedabad
3 Baddi-HP
4 Bangalore
5 Bhubneswar
6 Chennai
7 Coimbatore
8 Derabasi
9 Durgapur
10 Faridabad
11 Giaspura
12 Ghaziabad
13 Gurgaon
14 Gauhati
15 Goa
16 Hyderabad
17 Hubli
18 Indore
19 Jalandhar
20 Jaipur
21 Kochi
22 Kolkata
23 Kolhapur
24 Lalkuan
25 Lucknow
26 Ludhiana
27 Madura
28 Manipal
29 Mangalore
30 Mohali
31 Mumbai
32 Mysore
33 Nashik
34 Nagpur
35 Navi Mumbai
36 NOIDA
37 Panchkula
38 Pune
39 Ranchi
40 Raipur
41 Rajkot
42 Rudrapur
43 Sahibabad
45 Sonepat
46 Surat
47 Surajpur
48 Thane
49 Trichy
50 Tuticorin
51 Trivandram
52 Thrissur
53 Vapi
54 Vijaywada
55 Visakhapattanam
56 Vadodara
Size of Organized Concrete Industry
(including RMC Industry)
(Rough Estimates)
Year
Cement Consumption
through RMC Route
App. Concrete
Production
2012-13
7.5%
87 million m3
2017-18
10%
147 million m3
Assumptions
• Production figures include concrete produced from all sources using modern batching
and mixing plants (commercial and captive plants)
• Concrete production figure is calculated by assuming that the average cement
consumption is 300 kg/m3
Large Concrete Producing Countries
Statistics 2007 and (2012)
Country
•
•
•
•
•
•
USA
China
Spain
Italy
Turkey
India*
Concrete production, million m3
345
149
87.6
77.4
46.3
45*
(225)
87 mm3(N.A.)
( 2012)
(21.6)
(40)
(93)
??
Source: ERMCO
* Not authentic; contains organized concrete industry data collected from private sources.
147 mm3
( 2017)
RMC: A Mockery?
RMC: A Pretense or Farce?
Why Production Control Criteria?
• Unlike steel, aluminium, glass, etc. concrete is
processed but unfinished material at delivery time
• Factors affecting quality (including durability) :
• Controls exercised in process control measures during
production
• Variability in the properties of ingredients –
aggregates, cement, SCMs, etc.
• Variations in mix proportioning
• Concrete’s ultimate quality - compressive strength or
durability - cannot be verified at the time of sale
• Negligence or misinterpretation of standard methods of
testing
• Practices followed during
transportation, placement, consolidation and
curing/protection of concrete
Intermixing of Aggregates
No
Protection During Placing!
Intermixing of Aggregates
Calibration
• Accuracy and sensitivity of
weighing devices
– Tolerances specified in IS
4926
• Cement & SCMs:
– ± 2 percent of the quantity of
constituents being measured
• Aggregates, chemical
admixture and water:
– ± 3 percent of the quantity of
constituents being measured
Mixer Blade Worn Out
Built-up on Mixer Blade/Arm
Why Production Control Criteria?
Inside cleaned mixer
No Protection During Placing!
RMCMA Quality Scheme
Best Practices : Advanced Countries
USA
National Ready
Mixed
Concrete
Association, (N
RMCA)
1.
2.
Plant
Certification
Scheme
Quality
Management
System for
RMC Company
U.K.
Quality
Scheme for
Ready Mixed
Concrete
(QSRMC)
Quality &
Product
Conformity
Regulations
Canada
RMC
Association
of Ontario
State,
(RMCAO)
1.
2.
RMCAO Seal of
Concrete
Quality
RMCAO Seal of
Special
Concrete
Quality
Turkey
Turkish
Ready Mixed
Concrete
Association,
Third Party
Quality
Scheme
“KGS”
RMCMA Quality Scheme
• Indigenous in character
• Based on two strong pillars
– Best practices from advanced countries
– Strict adherence to various BIS codes of
practice
RMCMA Quality Manuals
u
B a mb
n a
De ga i
lh lo re
i
H y (NC
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N a ur
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ik
M Pu
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M o re
an
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C h pal
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Hu i
C o b li
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S
Va u r
A h d od at
m ar
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M d
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Ja e
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Tr r
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L u chy
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Ra hi
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No. of audited plants
City-wise Certified Plants
(March 2012)
30
20
10
5
28
25
25
224 Plants
50-plus locations
18
19
15
15
12
9
8
3
4
2
1
2
4
1
1
4
3
2
3
1
3
1
0
1
Efforts in Enhancing
Production Control Criteria
• Multi-stakeholder Ownership
• Auditing: Completely Independent character
• RMCMA signs MoU with QCI on Dec. 11, 2011 to
develop a New Quality Scheme
What is QCI ?
• Established under Cabinet decision in 1996, formed in
January 1997
• Registered as a non-profit autonomous society
• Joint initiative of the Government of India, and the Indian
Industry, represented by :
– Associated Chambers of Commerce and Industry of India
(ASSOCHAM)
– Confederation of Indian Industry (CII)
– Federation of Indian Chambers of Commerce & Industry (FICCI)
QCI: Objectives
Establish and maintain an accreditation structure in
the country
Provide right and unbiased information on quality
related standards
Facilitate upgradation of equipments and techniques
related to quality
Spread quality movement in the country through
National Quality Campaign
Represent India’s Interest in International forums
Help establish brand equity of Indian products and
service
Structure of New QCI Scheme
Quality Council of India
Steering Committee
Technical Committee
Certification Committee
Certification Bodies accredited by
NABCB of QCI
Multi Stake Holder Committees
• Participations from:
– Central Government Ministries, e.g.
Housing, MORT&H, etc.
– Key Specifier: Central Public Works Department
(CPWD)
– Central PSUs e.g. NHAI, AAI, etc.
– User bodies, e.g. BAI, CFI, etc.
– Professional bodies, e.g. ICI, ICCE
– Consultants, e.g. Mahendra Raj, TCPL, etc.
– Manufacturers, e.g. RMCMA, CMA
– Certifying bodies, e.g. BVCI, ICMQ
Quality Scheme: New Manuals
Criteria for
Production Control
of RMC
Certification
Process for
RMCPCS
Provisional
Approval for CBs for
RMCPCS
Download from http://qcin.org/CAS/RMCPC/
Two Schemes
• Ready-Mixed Concrete Plant Certification
Scheme (RMCPCS)
–RMC Capability Certification: A Must
–RMC 9000+ Certification: Optional
Scope of QCI Scheme
• Applicable for:
– RMC Plants supplying concrete commercially
– RMC plants supplying concrete for specific
project
– RMC Plants supplying concrete partly on
commercial basis and partly for captive
consumption
• Scheme excludes operations of
placing, compaction, finishing and curing of
concrete
Conforming Standards
• Provisions of QCI Scheme conform to:
–Bureau of Indian Standards
• IS 4926, IS 456, IS 8112, IS 12269, IS 383, IS
3812, IS 9103, IS 516, IS 1199, IS 2386, IS
15388, etc.
–Indian Roads Congress
• IRC 112, IRC 58, MORT&H Specifications
–Indian Railway Standards
• IRS Bridge code, IRST 89, IRST 45, etc.
Who are Qualified to Certify
RMC Plants?
• Bureau Veritas Certification (I) Pvt Ltd
(BVCI)
• ICMQ India
• Tata Projects Ltd.
Production Control Criteria:
Broad Contents
• Section A
– Resource Management
• Plant and equipment
• Laboratory
• Key personnel
– Control on quality of incoming materials
– Concrete design
– Production and delivery
– Control on process control equipments and maintenance
– Complaints
– Feedback
• Section B
– Check List (182 Item )
• Tables
– Table No 1 to 11
Resource Management
Resource
Management
Plant, Equipme
nt & Other
Utilities
Material
Storage
&
handling
Batching
Equipment
Central
Mixer
Key
Personnel
Laboratory
Educational
Level
Ticketing
System
Tests on
Aggregates
Test on
Concrete
Operational
Skills
Specific
Knowledge
Minimum Specified Lab Test
• Aggregates
– Sampling (IS 2430)
– Moisture content (IS 2386Part III)
– Bulk density (IS 2386-Part
III)
– Sieve analysis (IS 2386Part-I)
• Concrete
– Slump (IS 1199)
– Unit weight (IS 1199)
– Strength (IS 516)
Minimum Test Equipment &
Calibration Frequency
Relevant test
Slump test
Compressive strength of concrete
Preparing concrete test specimens
Sieve analysis of fine and coarse aggregates
BIS Standard
Minimum units
IS 1199-1959
2 sets
IS 516
One no.
IS 1199
30 nos.
IS 2386- Part I
Agg. Sampling (sieve shaker/sample divider)
Unit weight of concrete
Aggregates Bulk density
IS 2430
one set for C.A.
and F.A.
One
IS 1199
one no.
Silt content of sand
Specific gravity of aggregates
Other accessories
IS 2386- Part III one each for
C.A. and F.A.
one no.
one no.
•
Electronic weighing balance
One
•
Laboratory mixer(min 50 lit)
One
•
Electric microwave oven
•
Table / needle vibrator, tamping rods
One
•
Curing tank with temperature control
One
•
Shovels, trowels, flexible spatulas, meter,
Sufficient nos.
(IS 11332)
One
Quality of Incoming Materials
Material IS Conformity Physical and
Testing at NABL-accredited Lab
Requirements Chemical Testing
Cement
IS 8812 (OPC) Manufacturers’
•
IS 12269 (OPC) certificate for each •
IS 1489 (PPC) consignment
IS 455 (PSC)
First consignment of each brand
Once in a year for used brands or
change of source
Fly ash
IS 3812 (Part 1 Manufacturers’
•
and 2)
certificate for each
consignment
BIS conformity tests once in six
month or when source changed
GGBS
IS 12089 and
BS 6699
Manufacturers’
•
certificate for each
consignment
BIS/BS conformity tests once in six
month or when source changed
Silica
fume
IS 15388
Manufacturers’
•
certificate for each
consignment
BIS conformity tests once in six
month or when source changed
Quality of Incoming Materials
(con’d)
Material
IS Conformity Physical and
Requirements Chemical
Testing
Chemical
IS 9103
Admixtures
Water
Testing at NABL-accredited Lab
Manufacturers’ •
certificate for
each consignment •
IS 456 and
IS 4926
Coarse and IS 383
Fine
Aggregates
•
•
•
All code-specified tests before
finalization of source
BIS conformity tests once in six
month or when source changed
Non-mains water: Initially every
week for first 6 weeks and then at
3-monthly internal
Mains water: Annual basis once all
tests for source are satisfactory
All IS-specified tests during
selection of source or change of
source
Minimum tests in plant lab
Other tests at NABL-accredited
lab at IS-specified frequencies
Concrete Mix Design
• Organization should have the capability to
design concrete mixes by adopting any rational
method
• Organization should also have the ability to
convert prescribed and designed mixes into
batches of production
• Organization to keep records of trial mixes and
modifications done for the scrutiny of auditors
Production & Delivery
• Company to prove evidence that materials and quantities
batched are in accordance with order placed and
approved mix design
• Auditors shall choose and verify any five customer
orders during past three months, verifying following
basic parameters
Properties
Grade of concrete
Slump, mm
Minimum/maximum cementitious
content and Cement Type, if specified
Maximum water-binder ratio, if specified
Chemical admixture dosage, if specified
As ordered
As delivered
Control of Final Product
Fresh Concrete
a) Sampling
(IS a) Sampling: At least one sample for
4926 procedure)
every 50 m3 of production or every
50 batches whichever is of greater
frequency
b) At least one sample for every 50 m3
b) Slump test
of production or every 50 batches
c) Density of fresh
whichever is of greater frequency
concrete
c) At least once in a day
d) Placing
d) At least one sample for every 50 m3
Temperature of
of production or every 50 batches
#
the concrete
whichever is of greater frequency
a) IS 4926
b) IS 1199
c) IS 1199
d) IS 1199
Hardened concrete
a) Compressive
strength *
a) At least one sample for every 50 m3
of production or every 50 batches
whichever is of greater frequency *
IS 516
# optional test (if specified)
* One sample involves casting of 3 specimens of 150x150x150mm size, to be tested at 28 days.
Key Personnel
• Key personnel to be competent, adequately
qualified and trained
• Basic knowledge in concrete technology
essential
• QC in-charge to have degree/diploma in civil
engineering with min. 3 years of experience
• Lab Technicians to have knowledge and skills in
sampling and testing
• Identification of gaps in knowledge and efforts in
training personnel
Chronology of RMC Quality
Schemes : A Comparison
• USA
– 1913: Beginning of RMC production
– 1935: ASTM C 94 adopted first time
– 1965: Certification System commenced
30 years
• U. K.
–
–
–
–
1930: beginning of RMC production
1950: BRMCA formed
1968: “Authorisation Scheme”
1984: QSRMC launched
18 years
16 years
• India
–
–
–
–
1994: Beginning of commercial RMC
2002: RMCMA established
2008: Quality Scheme commenced
2013: QCI certification launched
6 years
5 years
Specifying Concrete as per
BS EN 8500 & ISO 22965
Methods of Specifying
Concrete
Designated concretes Production control certification essential
Designed concretes
Production control certification essential
Prescribed concretes
Production control certification not
essential
Standardized
Prescribed concretes
Production control certification not
essential
Proprietary concretes
Production control certification essential
Properties of Ingredient
Influencing Durability
Properties of Ingredient Influencing
Durability: Cement
Variation in Compressive
Strength of a Cement brand
during a Month
28-day comp. strength, MPa
65
60
55
50
45
61.52
58.82
57.48
53.47
53.1
Variation in Compressive
Strength of different Cement
Brands
80.0
71
70.0
60.0
50.0
60
58
51
51
55 56
61
61 60 59
55
49
03 days
40.0
07 days
30.0
28 days
20.0
10.0
40
0.0
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14
Properties of Ingredient Influencing
Durability: Cement
Strength, MPa
• No provision on
Uniformity Requirement
in compressive strength
of Cement in Indian
Codes!
• International standards
ASTM C 917 requirement on uniformity include such provision
80.0
• Some Indian
28-day SD= 1.01 MPa
70.0
manufacturer provide
60.0
50.0
uniformity data on
40.0
30.0
request
20.0
1-day SD= 1.04 MPa
10.0
• Urgent need to modify
0.0
Indian Standards on
cement to include this
Uniformity Chart of a major Indian brand
provision.
Properties of Ingredient Influencing
Durability: Aggregates
• Dredging restrictions on sand from natural
sources
• Industry constrained to use Crushed Stone Sand
(CSS)
• What constitutes CSS?
– IS 383 definition of CSS
• “Fine aggregate produced by crushing hard stone”
• IS 383 draft revision (2014) introduced one
more term - “Blended sand”
• “Fine aggregate produced by blending natural sand and
crushed stone sand or crushed gravel sand in suitable
proportions”
Silt content, % volume
Glimpses of Natural Sand Quality
Without washing)
40
35
30
25
After washing)
20
15
10
5
0
ep
-S
1
1
ep
-S
3
1
ep
-S
5
1
ep
-S
7
1
ep
-S
9
1
ep
-S
1
2
ep
-S
3
2
ep
-S
5
2
ep
-S
7
2
Properties of Ingredient Influencing
Durability: Aggregates
120
120
Nellore,
Tamil nadu
100
Paradeep,
Orrisa
100
80
80
60
60
Min.
40
Min.
40
20
20
0
10
4.75
2.36
R. SAND
1.18
0.6
Min.
R. SAND
0.3
10
0.15
Max.
Min.
0
Max.
CSS
Max.
4.75
2.36
R. SAND
CSS
120
1.18
Min.
Hospet,
Karnataka
0.3
Max.
Max.
0.15
CSS
120
Boisar
(near Mumbai)
100
100
0.6
80
80
60
Max.
60
Min.
40
Min.
40
20
20
0
10
0
10
4.75
2.36
1.18
0.6
0.3
0.15
4.75
R. SAND
2.36
1.18
Min.
0.6
0.3
Max.
Max.
0.15
CSS
Properties of Ingredient Influencing
Durability: Aggregates
Limits of deleterious materials (IS 383)
DELETERIOUS SUBSTANCE
SL.
NO.
METHOD OF
TEST
FINE AGGREGATE
PERCENTAGE BY
WEIGHT, Max
Uncrushed Crushed
(4)
(5)
1.00
1.00
COARSE AGGREGATE
PERCENTAGE BY
WEIGHT, Max
Uncrushed Crushed
(6)
(7)
1.00
1.00
(1)
(2)
i) Coal and Lignite
(3)
IS: 2386 (Part II)
ii)
Clay lumps
IS: 2386 (Part II)
1.00
1.00
1.00
1.00
iii)
Materials finer than 75-µ IS Sieve
IS: 2386 (Part I)
3.00
15.00
3.00
3.00
iv)
Soft fragments
IS: 2386 (Part II)
----
----
3.00
----
v)
Shale
IS: 2386 (Part II)
1.00
----
----
----
vi)
Total of percentages of all deleterious
materials (Except mica) including Sl.
No. (i) to (v) for Col 4,6,7 and Sl. No.
(i) and (ii) for Col 5 only.
----
5.00
2.00
5.00
5.00
NOTE 1 -The presence of mica in the fine aggregate has been found to reduce considerably the durability and compressive strength of
concrete and further investigations are underway to determine the extent of the deleterious effect of mica. It is advisable, therefore, to
investigate the mica content of fine aggregate and make suitable allowances for the possible reduction in the strength of concrete or mortar.
NOTE 2- The aggregate shall not contain harmful organic impurities [tested in accordance with IS:2386 ( Part II )- I963 ] in sufficient
quantities to affect adversely the strength or durability of concrete. A fine aggregate which fails in the test organic impurities may be used,
provided that, when tested for the effect of organic impurities on the strength of mortar, the relative strength at 7 and 28 days, reported
accordance with 7 of IS : 2386 (Part VI )-1963 is not less than 95 percent.
Microfine Content
• Research Report ICAR 102-1F
– “Good quality concrete can be made with
amounts of microfines (particles passing 75µ
sieve) as high as 15%. In fact, most of the
concrete made with MFA in both projects
surpassed the concrete made with natural sand
in terms of strength, resistance to chloride ion
penetration, and abrasion”*
• New Zealand experience
– For low to medium compressive strengths, the
optimum % of microfines can be as high as 18%#
•Concrete Mixtures with High Microfines by Pedro N. Quiroga, Namshik Ahn, and David W. Fowler, ACI Materials Journal, Aug 2006
•# Manufactured sands in Portland cement concrete – The New Zealand Experience, by S. Goldsworthy
Suggested Grading Limits of
Manufactured Sand
General Grading Limits
Sieve size
4.75 mm
0.6 mm
0.075 mm
Cumulative amount passg,
%
90-100
15-80
0-20
Limits of Deviations
Sieve size, mm
9.5
4.75
2.36
1.18
0.6
0.3
0.15
0.075
Maximum
deviation, %
±5
±10
±15
±15
±10
±5
±3
Properties of Ingredient Influencing
Durability: Fly Ash
Uniformity Requirement of Fly Ash
Blaine's fineness
320 m2/kg (min)
Particles retained on 45 µ sieve
34% (max)
Lime reactivity
4.5 MPa (min)
28-day Compressive strength
Not less than 80% of control
Variation
in Fly
Ash
Quality
% retained on 45 micron
sieve
IS 3812 requirement
50
40
30
20
10
0
Dominant Grades of Concrete
supplied by major RMC Players
30
25
30
25
20
15
10
5
0
20
20
25
25
25
Customer Specified Mixes:
Some Examples
Customer-Specified Mixes: Some
Examples (Grade M25)
Region
Exposure
class
w/b ratio
Mumbai
Not specified
Not specified
380
-
380*
Not specified
Not specified
300
100 (25%)
400*
Not specified
Not specified
380
-
380*
Not specified
Not specified
290
90 (24%)
380*
Goa
Not specified
Not specified
380
-
380*
Coastal
Karnataka
Not specified
0.48
400
-
400*
Not specified
Not specified
315
65 (17%)
380*
NCR
OPC,
kg
Fly ash,
kg
Total
cementitious,
kg
* IS 456 specifies minimum cementitious content of 300 kg and w/b= 0.50
Customer-Specified Mixes: Some
Examples (Grade M30)
Region
Exposure
class
w/b ratio
OPC, kg
Fly ash,
kg
Total
cementitious,
kg
Mumbai
Not specified
Not specified
350
-
350*
Not specified
Not specified
400
40 (9%)
400*
Not specified
Not specified
400
-
400*
Not specified
Not specified
310
95 (23%)
390*
Goa
Not specified
Not specified
400
-
400*
Coastal
Karnataka
Not specified
0.44
420
-
420*
Not specified
Not specified
380
50 (11%)
430*
NCR
* IS 456 specifies minimum cementitious content of 320 kg and w/b= 0.45
Customer-Specified Mixes: Some
Examples (Grade M35)
Region
Exposure
class
w/b ratio
OPC, kg
Fly ash,
kg
Total
cementitious,
kg
Mumbai
Not specified
Not specified
450
-
450*
Not specified
Not specified
390
90 (19%)
480*
Not specified
Not specified
395
95 (19%)
490*
Not specified
Not specified
365
73 (17%)
438*
Goa
Not specified
Not specified
420
-
420*
Coastal
Karnataka
Not specified
Not specified
390
90 (19%)
480*
Not specified
Not specified
-
-
-
NCR
* IS 456 specifies minimum cementitious content of 340 kg and w/b= 0.45
Mix Optimization
• Currently, little freedom given to RMC
players to optimize mixes even for
strength - leave apart durability
• Result:
• Uneconomical mixes devoid of
durability and sustainability
• Shrinkage cracking owing to higher
cement and water contents
• Usual blame goes to RMC producer
Two strong restraints in
production
Min. cement
content
Max. fly ash
content
Why cracks
in my
concrete ?
Customer
RMC
Producer
Need of the Hour
• “Try to give the producer as much choice
as possible.” – Clause 5.2.1 of ISO 22965Part I
• Provide freedom to RMC producer to
design his own mix – under “designed
mix” category as permitted under IS
4926
• Encourage optimization of mixes for
strength and durability
Improving Durability through
Enhanced utilization of SCMs
Code-specified Upper Limit on SCMs
Pozzolanic
materials like fly
ash (conforming
to IS 3812)
35%
Ground
Granulated Blast- 70%
furnace Slag
(conforming to IS
12089)
Typical HVFAC mix
Grade of OPC, Fly
Total
w/b
Concrete kg Ash, Cementitious ratio
kg materials, kg
M20
170
170
40
30
26.48
10
28-day
56-day
100
112
136
90 day
Compressive strength
90-day
57
7 day
7-day
140
120
100
80
60
40
20
0
160
56 day
13.63
0.44
28 day
20
23.72
32.31
340
Slump,
mm
Other Examples of HVFAC
Grade
OPC, kg
FA, kg
Total Cementitious,
kg
w/b
ratio
Slump,
mm
M30
160
160
320
0.45
150
M40
180
180
360
0.43
170
50
44.64
45
39.99
40
34.65
35
42.26
37.63
20
160
120
80
30
25
200
21.34
40
26.27
122
115
143
169
7 day 28 day
56 day
90 day
72
100
0
18.92
15
7-day
61
100
28-day
56-day
90-day
Typical Triple Blend Concrete
Grade of
Concrete
OPC,
kg
Fly Ash,
kg
GGBS,
Kg
M20
125
100
75
Total
w/b ratio
Cementitious
material, kg
300
0.55
Slump,
mm
110
160
120
80
40
57
100
122
156
0
7 day
28 day
56 day
90 day
Recent Changes in Durability
Specifications of IRST and IRC
IRST Concrete Bridge Code (1997)
• Exposure classes similar to those in IS 456
• Provisions of maximum w/b ratio and min.
cementitious contents
• Permeability test shall be mandatory for all RCC/PSC
bridges under severe, very severe and extreme
environment
• The depth of penetration shall not exceed 25mm
IRST Guidelines for HPC
• Cementitious content
– not less than 380 kg/m3 and not more than 450 kg/m3
– W/c ratio not less than 0.33 and not more than 0.40
• RCPT value shall be less than 800 coulombs.
• Additional durability tests, such as, Water
Permeability test as per DIN: 1048 Part 5-1991 or
Initial Surface Absorption test as per BS:1881 Part 5
can also be specified.
• The permissible values in such tests shall be decided
taking into account the severity of the exposure
conditions.
IRC 112: Durability Recommendations
for 100 Year Service Life
Exposure
Condition
Moderate
Severe
Very Severe
Extreme
Max.
watercement
ratio
0.45
0.45
0.40
0.35
Min.
cement
content,
kg/m3
340
360
380
400
Minimum
grade of
concrete
Minimum
cover, mm
M25
M30
M40
M45
40
45
50
75
Source: Code of Practice for Concrete Road Bridges, IRC 112-2011
IRC 112: Durability Tests
• Suggested upper limits for 56-day RCPT value
Exposure Class
Severe
Very severe
Extreme
RCPT @ 56 days
1500
1200
800
• Additionally suggested tests
– Water permeability (DIN 1048)
– ISAT (BS1881-Part 5)
• Acceptance criteria
– To be arrived at prior to testing
No permissible values
suggested
Metro Rail Specifications
• Mumbai Metro: Durability Specifications
Water Penetration Test (DIN
1048)
RCPT
value
Not greater than
25mm @ 28 day
Not greater than:
2500 Columbs for M-30 and
1500 Columbs for M-45 and higher
• Chennai Metro: Durability Specifications
Water Penetration Test (DIN 1048)
Not greater than 10mm @ 28-35day
Drying Shrinkage
Not greater than 0.05% @ 28day
Moisture Movement
RCPT
Value
Not greater than 0.03% @ 28day
Not greater than
600 Coloumbs @ 90day
Lab Data on RCPT &
Compressive Strength
Rapid Chloride Ion Permeability Test
(RCPT)
• Why RCPT is popular in spite of
shortcomings?
•
•
•
•
RCPT is a rapid test
It provides a good indication of the
degree of penetrability of concrete.
It is a measure of conductivity governed by the volume, size and
connectivity of pores
Good co-relationship between RCPT data
and ponding test
“In spite of other developments, it is
likely that this test (RCPT) will remain
as an index test for permeability for
many years to come”*
* Hearn, N, Hooton, R. J, and Nokken, M. Pore structure, permeability and penetration resistance characteristics of concrete.. Significance of tests and properties of concrete and
concrete making materials, ASTM STP 169D, ASTM International, 2006, pp. 237-252.
RCPT and Strength Data
(OPC 350 kg/m3 and w/c ratio = 0.50)
6000
50
5510
45
RCPT Value, Coloumb
5000
40
3572
4000
35
3451
30
3198
25
3000
2489
2000
20
15
10
1000
5
0
0
0
35
40
45
50
% Replacement of OPC by Fly Ash
28-day RCPT
28-day Comp. strength
• 28-day RCPT Values and Compressive strength for different replacement
levels of OPC by Fly Ash
RCPT and Strength Data
(OPC 400 kg/m3 and w/c ratio = 0.44)
60
4000
3630
3500
50
COmpressive strength, MPa
3000
40
2500
2275
2000
30
1627
1480
1420
1495
20
1340
1500
1000
10
500
0
0
0
35
40
45
50
60
70
% Replacement of OPC by Fly Ash
28-day Comp. strength
28-day RCPT
• 28-day RCPT Values and Compressive strength for different replacement
levels of OPC by Fly Ash
Conclusion
• When ordering concrete, it will be appropriate
to specify:
– Third-party production control criteria and
certification
– Exposure conditions
– Higher % utilization of SCMs
– Allow freedom to RMC supplier to optimize
concrete mixes to achieve desired strengths and
durability
– Provide incentives for producers optimizing mixes
for strength and durability
– Specify durability tests and permissible limits
Future …
• Evolve Guidelines Document for specifying
durability (on lines of ISO 22965 – Part I and II*)
– New definition of exposure classes
– Properties of concrete constituents including their
uniformity requirements
– Encourage increased utilization of SCMs for enhancing
durability and sustainability
– Upgraded production control criteria
– Durability requirements including conformity criteria
for different tests
– Encourage service life design and specify service life
requirements
* ISO 22965-1, Concrete – Part 1: Methods of specifying and guidance for the specifier
* ISO 22965-2, Concrete – Part 2: Specification of constituent materials, production of concrete and conformity of concrete
Thank You!
• RCPT Shortcomings
–
–
–
–
Current passed is related to all ions
Measurement made before any steady state migration is achieved
High voltage may increase temperature
Presence of fibers, calcium nitrite increases the value of coulombs