Concrete Durability: Industry Perspectivetheconcreteportal.com/vijaykulkarni.pdf · Preparing...

Vijay KulkarniPrincipal Consultant, Ready-Mixed Concrete Manufacturers’

Association (RMCMA)Former President, Indian Concrete Institute (ICI)Former Editor, The Indian Concrete Journal (ICJ)

IITM –IITB-ICI Workshop on Achieving Durable Concrete Construction Through Performance Testing

(Feb. 2014)

Concrete Durability: Industry Perspective*

* 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

Twin-Shaft Mixer

Cement/SCM Silos

Aggregate Conveyor

Aggregate Bins

1st Phase of Development

• Establishment of RMC facilities in metropolitan centres

Mumbai

Bangalore

Kolkata

Delhi

Chennai

Hyderabad

2nd Phase of Development

•

•

••

•

•••••

•

••

•

•

•• ••••

•••

•

••••••

•

•

•••

••

1Amritsar 29Mangalore2Ahmedabad 30Mohali3Baddi-HP 31Mumbai4Bangalore 32Mysore5Bhubneswar 33Nashik6Chennai 34Nagpur7Coimbatore 35Navi Mumbai8Derabasi 36NOIDA9Durgapur 37Panchkula

10Faridabad 38Pune11Giaspura 39Ranchi12Ghaziabad 40Raipur13Gurgaon 41Rajkot14Gauhati 42Rudrapur15Goa 43Sahibabad16Hyderabad 45Sonepat17Hubli 46Surat18Indore 47Surajpur19Jalandhar 48Thane20Jaipur 49Trichy21Kochi 50Tuticorin22Kolkata 51Trivandram23Kolhapur 52Thrissur24Lalkuan 53Vapi25Lucknow 54Vijaywada26Ludhiana 55Visakhapattanam27Madura 56Vadodara28Manipal

56 Major Cities

Size of Organized Concrete Industry(including RMC Industry)

Year Cement Consumption through RMC Route

App. Concrete Production

2012-13 7.5% 87 million m3

(Rough Estimates)

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

2017-18 10% 147 million m3

Large Concrete Producing CountriesStatistics 2007 and (2012)

Country Concrete production, million m3

• USA 345 (225)• China 149 (N.A.)

• Spain 87.6 (21.6)• Italy 77.4 (40)• Turkey 46.3 (93)• India* 45* ??

87 mm3

( 2012)

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 Intermixing of Aggregates

• 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 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

Quality & Product Conformity Regulations

CanadaRMC Association of Ontario State, (RMCAO)

USANational Ready Mixed Concrete Association, (NRMCA)

1. Plant Certification Scheme

2. Quality Management System for RMC Company

U.K.Quality Scheme for Ready Mixed Concrete (QSRMC)

1. RMCAO Seal of Concrete Quality

2. RMCAO Seal of Special Concrete Quality

TurkeyTurkish Ready Mixed Concrete Association,

Third Party Quality Scheme “KGS”

http://www.thbb.org/Content.aspx?ID=4�

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

City-wise Certified Plants(March 2012)

18

2528

15

9

3 42 1

12

2 1

19

14 4 3

8

2 31

31 1

0

5

10

15

20

25

30

Mumbai

Bangalo

re

Delhi (N

CR)

Hyderab

adKolk

ata Goa

Coimbat

oreNagp

urNash

ikPune

Mangalo

re

Manipal

Chennai Hubli

Cochin

Surat

Vadodara

Ahmedaba

dMyso

reJai

purTric

hy

Lucknow

RanchiRaip

ur

No. o

f aud

ited

plan

ts

224 Plants50-plus locations

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 inJanuary 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 countryProvide right and unbiased information on quality

related standardsFacilitate upgradation of equipments and techniques

related to qualitySpread quality movement in the country through

National Quality CampaignRepresent India’s Interest in International forumsHelp 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/

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.

• 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

Production Control Criteria: Broad Contents

Resource Management

Resource Management

Plant, Equipment & Other

Utilities

Material Storage

& handling

Batching Equip-ment

Central Mixer

Ticketing System

Laboratory

Tests on Aggre-gates

Test on Concrete

Key Personnel

Educational Level

Opera-tionalSkills

Specific Knowledge

Minimum Specified Lab Test

• Aggregates – Sampling (IS 2430)– Moisture content (IS 2386-

Part III)– Bulk density (IS 2386-Part

III)– Sieve analysis (IS 2386-

Part-I)• Concrete

– Slump (IS 1199)– Unit weight (IS 1199)– Strength (IS 516)

Minimum Test Equipment & Calibration Frequency

Relevant test BIS Standard Minimum units

Slump test IS 1199-1959 2 sets

Compressive strength of concrete IS 516 One no.

Preparing concrete test specimens IS 1199 30 nos.

Sieve analysis of fine and coarse aggregates IS 2386- Part I one set for C.A. and F.A.

Agg. Sampling (sieve shaker/sample divider) IS 2430 One

Unit weight of concrete IS 1199 one no.

Aggregates Bulk density IS 2386- Part III one each for C.A. and F.A.

Silt content of sand one no.

Specific gravity of aggregates one no.

Other accessories• Electronic weighing balance One

• Laboratory mixer(min 50 lit) One

• Electric microwave oven (IS 11332) One

• Table / needle vibrator, tamping rods One

• Curing tank with temperature control One

• Shovels, trowels, flexible spatulas, meter, Sufficient nos.

Quality of Incoming Materials

Material IS Conformity Requirements

Physical and Chemical Testing

Testing at NABL-accredited Lab

Cement IS 8812 (OPC)IS 12269 (OPC)IS 1489 (PPC)IS 455 (PSC)

Manufacturers’ certificate for each consignment

• First consignment of each brand• Once in a year for used brands or

change of source

Fly ash IS 3812 (Part 1 and 2)


• BIS conformity tests once in six month or when source changed

GGBS IS 12089 and BS 6699


• BIS/BS conformity tests once in six month or when source changed

Silica fume

IS 15388 Manufacturers’ certificate for each consignment


Quality of Incoming Materials (con’d)

Material IS Conformity Requirements

Physical and Chemical Testing

Testing at NABL-accredited Lab

Chemical Admixtures

IS 9103 Manufacturers’ certificate for each consignment

• All code-specified tests before finalization of source


Water IS 456 and IS 4926

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

Coarse and Fine Aggregates

IS 383 • 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 As ordered As deliveredGrade of concrete

Slump, mm

Minimum/maximum cementitiouscontent and Cement Type, if specified

Maximum water-binder ratio, if specified

Chemical admixture dosage, if specified

Control of Final ProductFresh Concrete

a) Sampling (IS4926 procedure)

b) Slump testc) Density of fresh

concrete d) Placing

Temperature of the concrete #

a) Sampling: At least one sample for every 50 m3 of production or every 50 batches whichever is of greater frequency

b) At least one sample for every 50 m3

of production or every 50 batches whichever is of greater frequency

c) At least once in a dayd) At least one sample for every 50 m3

of production or every 50 batches whichever is of greater frequency

a) IS 4926

b) IS 1199

c) IS 1199d) 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

• U. K.– 1930: beginning of RMC production– 1950: BRMCA formed– 1968: “Authorisation Scheme”– 1984: QSRMC launched

• India– 1994: Beginning of commercial RMC– 2002: RMCMA established– 2008: Quality Scheme commenced– 2013: QCI certification launched

30 years

18 years

6 years

16 years

5 years

Specifying Concrete as per BS EN 8500 & ISO 22965

Methods of Specifying ConcreteDesignated 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

5158

51

6055 56

61

71

61 60 5955

49

0.0

10.0

20.0

30.0

40.0

50.0

60.0

70.0

80.0

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14

03 days

07 days

28 days

Variation in Compressive Strength of different Cement Brands

Variation in Compressive Strength of a Cement brand during a Month

61.5258.82

53.47 53.1

57.48

40

45

50

55

60

65

28-day comp. strength, MPa

Properties of Ingredient Influencing Durability: Cement

• No provision on Uniformity Requirement in compressive strength of Cement in Indian Codes!

• International standards include such provision

• Some Indian manufacturer provide uniformity data on request

• Urgent need to modify Indian Standards on cement to include this provision.

0.010.020.030.040.050.060.070.080.0

Stre

ngth

, MPa

1-day SD= 1.04 MPa

28-day SD= 1.01 MPa

ASTM C 917 requirement on uniformity

Uniformity Chart of a major Indian brand

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”

Glimpses of Natural Sand Quality

05

10152025303540

11-S

ep

13-S

ep

15-S

ep

17-S

ep

19-S

ep

21-S

ep

23-S

ep

25-S

ep

27-S

ep

Silt

cont

ent,

% v

olum

e

After washing)

Without washing)


Min.

Max.

0

20

40

60

80

100

120

10 4.75 2.36 1.18 0.6 0.3 0.15

R. SAND Min. Max. CSS

Hospet, Karnataka

Min.

Max.0

20

40

60

80

100

120

10 4.75 2.36 1.18 0.6 0.3 0.15


Paradeep, Orrisa

Min.

Max.0

20

40

60

80

100

120

10 4.75 2.36 1.18 0.6 0.3 0.15


Nellore, Tamil nadu

Min.

Max.0

20

40

60

80

100

120

10 4.75 2.36 1.18 0.6 0.3 0.15


Boisar(near Mumbai)


Limits of deleterious materials (IS 383) SL. NO.

DELETERIOUS SUBSTANCE METHOD OF TEST

FINE AGGREGATE PERCENTAGE BY

WEIGHT, Max

COARSE AGGREGATE PERCENTAGE BY

WEIGHT, MaxUncrushed Crushed Uncrushed Crushed

(1) (2) (3) (4) (5) (6) (7)i) Coal and Lignite IS: 2386 (Part II) 1.00 1.00 1.00 1.00ii) 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 ofconcrete and further investigations are underway to determine the extent of the deleterious effect of mica. It is advisable, therefore, toinvestigate 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 sufficientquantities 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, reportedaccordance 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

Sieve size Cumulative amount passg, %

4.75 mm 90-1000.6 mm 15-80

0.075 mm 0-20

Sieve size, mm Maximum deviation, %

9.5 -4.75 ± 52.36 ±101.18 ±150.6 ±150.3 ±100.15 ± 5

0.075 ± 3

General Grading Limits

Limits of Deviations

Properties of Ingredient Influencing Durability: 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

01020304050

% r

etai

ned

on 4

5 m

icro

n si

eve

Uniformity Requirement of Fly Ash

Variation in Fly Ash Quality

IS 3812 requirement

Dominant Grades of Concrete supplied by major RMC Players

05

1015202530

30

20 2025 25 25 25

Customer Specified Mixes: Some Examples

Customer-Specified Mixes: Some Examples (Grade M25)

Region Exposure class

w/b ratio OPC, kg

Fly ash, kg

Total cementitious, kg

Mumbai Not specified Not specified 380 - 380*

Not specified Not specified 300 100 (25%) 400*

NCR Not specified Not specified 380 - 380*


Goa Not specified Not specified 380 - 380*

Coastal Karnataka

Not specified 0.48 400 - 400*


* IS 456 specifies minimum cementitious content of 300 kg and w/b= 0.50



w/b ratio OPC, kg Fly ash, kg




NCR Not specified Not specified 400 - 400*



Coastal Karnataka

Not specified 0.44 420 - 420*





w/b ratio OPC, kg Fly ash, kg




NCR Not specified Not specified 395 95 (19%) 490*



Coastal Karnataka


Not specified Not specified - - -


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

Why cracks in my

concrete ?

Max. fly ash content

Min. cement content RMC

ProducerCustomer

Need of the Hour

• “Try to give the producer as much choice as possible.” – Clause 5.2.1 of ISO 22965-Part 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 Pozzolanicmaterials like fly ash (conforming to IS 3812)

35%

Ground Granulated Blast-furnace Slag (conforming to IS 12089)

70%

Typical HVFAC mix

Grade of Concrete

OPC,kg

Fly Ash, kg

Total Cementitious materials, kg

w/b ratio

Slump, mm

M20 170 170 340 0.44 160

13.63

23.7226.48

32.31

10

20

30

40

7-day 28-day 56-day 90-day

Compressive strength

020406080

100120140

7 day

28 day

56 day

90 day

57100 112 136

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

18.92

26.27

37.63

44.64

21.34

34.65

39.99 42.26

15

20

25

30

35

40

45

50

7-day 28-day 56-day 90-day

0

40

80

120

160

200

7 day 28 day 56 day 90 day

72 100 143 16961100 115 122

Typical Triple Blend Concrete

0

40

80

120

160

7 day 28 day 56 day 90 day

57100 122

156

Grade of Concrete

OPC, kg

Fly Ash, kg

GGBS,Kg

Total Cementitious material, kg

w/b ratio Slump, mm

M20 125 100 75 300 0.55 110

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

Max. water-cement

ratio

Min. cement content, kg/m3

Minimum grade of concrete

Minimum cover, mm

Moderate 0.45 340 M25 40Severe 0.45 360 M30 45

Very Severe 0.40 380 M40 50Extreme 0.35 400 M45 75

Source: Code of Practice for Concrete Road Bridges, IRC 112-2011

IRC 112: Durability Tests

• Suggested upper limits for 56-day RCPT value

• Additionally suggested tests – Water permeability (DIN 1048)– ISAT (BS1881-Part 5)

• Acceptance criteria– To be arrived at prior to testing

Exposure Class RCPT @ 56 daysSevere 1500

Very severe 1200Extreme 800

No permissible values suggested

Metro Rail Specifications

• 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 Not greater than 0.03% @ 28dayRCPT Value

Not greater than 600 Coloumbs @ 90day

Water Penetration Test (DIN 1048)

Not greater than 25mm @ 28 day

RCPT value

Not greater than: 2500 Columbs for M-30 and

1500 Columbs for M-45 and higher

• Mumbai Metro: Durability Specifications

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

• 28-day RCPT Values and Compressive strength for different replacement levels of OPC by Fly Ash

(OPC 350 kg/m3 and w/c ratio = 0.50)

5510

35723451

3198

2489

0

5

10

15

20

25

30

35

40

45

50

0

1000

2000

3000

4000

5000

6000

0 35 40 45 50

RCPT

Val

ue, C

olou

mb

% Replacement of OPC by Fly Ash

28-day RCPT 28-day Comp. strength

RCPT and Strength Data

• 28-day RCPT Values and Compressive strength for different replacement levels of OPC by Fly Ash

3630

2275

1495

1627 14801420 1340

0

500

1000

1500

2000

2500

3000

3500

4000

0

10

20

30

40

50

60

0 35 40 45 50 60 70

COm

pres

sive

stre

ngth

, MPa

% Replacement of OPC by Fly Ash

28-day Comp. strength 28-day RCPT

(OPC 400 kg/m3 and w/c ratio = 0.44)

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

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