Concrete Durability: Industry Perspective *

Transcription

1 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

2 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

3 Vestige of Recent Past Courtesy: Mahesh Tendulkar

4 Typical Modern RMC Plant Cement/SCM Silos Aggregate Conveyor Twin-Shaft Mixer Aggregate Bins

5 1 st Phase of Development Delhi Establishment of RMC facilities in metropolitan centres Kolkata Mumbai Hyderabad Bangalore Chennai

6 2 nd Phase of Development 56 Major Cities 1 Amritsar 29 Mangalore 2 Ahmedabad 30 Mohali 3 Baddi-HP 31 Mumbai 4 Bangalore 32 Mysore 5 Bhubneswar 33 Nashik 6 Chennai 34 Nagpur 7 Coimbatore 35 Navi Mumbai 8 Derabasi 36 NOIDA 9 Durgapur 37 Panchkula 10 Faridabad 38 Pune 11 Giaspura 39 Ranchi 12 Ghaziabad 40 Raipur 13 Gurgaon 41 Rajkot 14 Gauhati 42 Rudrapur 15 Goa 43 Sahibabad 16 Hyderabad 45 Sonepat 17 Hubli 46 Surat 18 Indore 47 Surajpur 19 Jalandhar 48 Thane 20 Jaipur 49 Trichy 21 Kochi 50 Tuticorin 22 Kolkata 51 Trivandram 23 Kolhapur 52 Thrissur 24 Lalkuan 53 Vapi 25 Lucknow 54 Vijaywada 26 Ludhiana 55 Visakhapattanam 27 Madura 56 Vadodara 28 Manipal

7 Size of Organized Concrete Industry (including RMC Industry) (Rough Estimates) Year Cement Consumption through RMC Route App. Concrete Production % 87 million m % 147 million m 3 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/m 3

8 Large Concrete Producing Countries Statistics 2007 and (2012) Country Concrete production, million m 3 USA 345 (225) China 149 (N.A.) 87 mm 3 ( 2012) Spain 87.6 (21.6) Italy 77.4 (40) Turkey 46.3 (93) India* 45*?? 147 mm 3 ( 2017) Source: ERMCO * Not authentic; contains organized concrete industry data collected from private sources.

9 RMC: A Mockery?

10 RMC: A Pretense or Farce?

11 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!

12 Intermixing of Aggregates

13 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

14 Mixer Blade Worn Out

15 Built-up on Mixer Blade/Arm Why Production Control Criteria? Inside cleaned mixer

16 No Protection During Placing!

17 RMCMA Quality Scheme

18 Best Practices : Advanced Countries USA National Ready Mixed Concrete Association, (N RMCA) U.K. Quality Scheme for Ready Mixed Concrete (QSRMC) Canada RMC Association of Ontario State, (RMCAO) Turkey Turkish Ready Mixed Concrete Association, 1. Plant Certification Scheme 2. Quality Management System for RMC Company Quality & Product Conformity Regulations 1. RMCAO Seal of Concrete Quality 2. RMCAO Seal of Special Concrete Quality Third Party Quality Scheme KGS

19 RMCMA Quality Scheme Indigenous in character Based on two strong pillars Best practices from advanced countries Strict adherence to various BIS codes of practice

20 RMCMA Quality Manuals

21 City-wise Certified Plants (March 2012) No. of audited plants Mumbai Bangalore Delhi (NCR) Hyderabad Kolkata Goa Coimbatore Nagpur Nashik Pune Mangalore Manipal Chennai Hubli Cochin Plants 50-plus locations Surat Vadodara Ahmedabad Mysore Jaipur Trichy 1 3 Lucknow Ranchi Raipur 1 1

22 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

23 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)

24 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

25 Structure of New QCI Scheme Quality Council of India Steering Committee Technical Committee Certification Committee Certification Bodies accredited by NABCB of QCI

26 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

27 Quality Scheme: New Manuals Criteria for Production Control of RMC Certification Process for RMCPCS Provisional Approval for CBs for RMCPCS Download from

28 Two Schemes Ready-Mixed Concrete Plant Certification Scheme (RMCPCS) RMC Capability Certification: A Must RMC Certification: Optional

29 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

30 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.

31 Who are Qualified to Certify RMC Plants? Bureau Veritas Certification (I) Pvt Ltd (BVCI) ICMQ India Tata Projects Ltd.

32 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

33 Resource Management Resource Management Plant, Equipme nt & Other Utilities Laboratory Key Personnel Material Storage & handling Batching Equipment Central Mixer Ticketing System Test on Concrete Educational Level Tests on Aggregates Operational Skills Specific Knowledge

34 Minimum Specified Lab Test Aggregates Sampling (IS 2430) Moisture content (IS Part III) Bulk density (IS 2386-Part III) Sieve analysis (IS Part-I) Concrete Slump (IS 1199) Unit weight (IS 1199) Strength (IS 516)

35 Minimum Test Equipment & Calibration Frequency Relevant test BIS Standard Minimum units Slump test IS sets Compressive strength of concrete IS 516 One no. Preparing concrete test specimens IS nos. Sieve analysis of fine and coarse aggregates IS 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 Part III one each for Silt content of sand Specific gravity of aggregates Other accessories Electronic weighing balance One C.A. and F.A. one no. one no. 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.

36 Quality of Incoming Materials Material IS Conformity Requirements Cement IS 8812 (OPC) IS (OPC) IS 1489 (PPC) IS 455 (PSC) Fly ash IS 3812 (Part 1 and 2) Physical and Chemical Testing Manufacturers certificate for each consignment Manufacturers certificate for each consignment Testing at NABL-accredited Lab First consignment of each brand Once in a year for used brands or change of source BIS conformity tests once in six month or when source changed GGBS IS and BS 6699 Manufacturers certificate for each consignment BIS/BS conformity tests once in six month or when source changed Silica fume IS Manufacturers certificate for each consignment BIS conformity tests once in six month or when source changed

37 Quality of Incoming Materials (con d) Material Chemical Admixtures Water Coarse and Fine Aggregates IS Conformity Requirements IS 9103 IS 456 and IS 4926 Physical and Chemical Testing Manufacturers certificate for each consignment Testing at NABL-accredited Lab 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 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

38 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

39 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 delivered 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

40 Control of Final Product Fresh Concrete a) Sampling (IS 4926 procedure) b) Slump test c) Density of fresh concrete d) Placing Temperature of the concrete # Hardened concrete a) Compressive strength * a) Sampling: At least one sample for every 50 m 3 of production or every 50 batches whichever is of greater frequency b) At least one sample for every 50 m 3 of production or every 50 batches whichever is of greater frequency c) At least once in a day d) At least one sample for every 50 m 3 of production or every 50 batches whichever is of greater frequency a) At least one sample for every 50 m 3 of production or every 50 batches whichever is of greater frequency * a) IS 4926 b) IS 1199 c) IS 1199 d) IS 1199 IS 516 # optional test (if specified) * One sample involves casting of 3 specimens of 150x150x150mm size, to be tested at 28 days.

41 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

42 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 18 years 16 years 30 years 6 years 5 years

43 Specifying Concrete as per BS EN 8500 & ISO Methods of Specifying Concrete Designated concretes Production control certification essential Designed concretes Production control certification essential Prescribed concretes Standardized Prescribed concretes Proprietary concretes Production control certification not essential Production control certification not essential Production control certification essential

44 Properties of Ingredient Influencing Durability

45 Properties of Ingredient Influencing Durability: Cement Variation in Compressive Strength of a Cement brand during a Month Variation in Compressive Strength of different Cement Brands day comp. strength, MPa days 07 days 28 days

46 Properties of Ingredient Influencing Durability: Cement Strength, MPa ASTM C 917 requirement on uniformity day SD= 1.01 MPa 1-day SD= 1.04 MPa Uniformity Chart of a major Indian brand 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.

47 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

48 Glimpses of Natural Sand Quality Silt content, % volume Without washing) After washing) 11-Sep 13-Sep 15-Sep 17-Sep 19-Sep 21-Sep 23-Sep 25-Sep 27-Sep

49 Properties of Ingredient Influencing Durability: Aggregates Nellore, Tamil nadu Paradeep, Orrisa Min Min Max Max R. SAND Min. Max. CSS R. SAND Min. Max. CSS R. SAND Min. Max. CSS Min. Max. Hospet, Karnataka Min. Boisar (near Mumbai) Max R. SAND Min. Max. CSS

50 Properties of Ingredient Influencing Durability: Aggregates SL. NO. DELETERIOUS SUBSTANCE Limits of deleterious materials (IS 383) METHOD OF TEST FINE AGGREGATE PERCENTAGE BY WEIGHT, Max COARSE AGGREGATE PERCENTAGE BY WEIGHT, Max Uncrushed Crushed Uncrushed Crushed (1) (2) (3) (4) (5) (6) (7) i) Coal and Lignite IS: 2386 (Part II) ii) Clay lumps IS: 2386 (Part II) iii) Materials finer than 75-µ IS Sieve IS: 2386 (Part I) iv) Soft fragments IS: 2386 (Part II) v) Shale IS: 2386 (Part II) 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 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.

51 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

52 Suggested Grading Limits of Manufactured Sand General Grading Limits Sieve size Cumulative amount passg, % 4.75 mm mm mm 0-20 Limits of Deviations Sieve size, mm Maximum deviation, % ± ± ± ± ± ± ± 3

53 Properties of Ingredient Influencing Durability: Fly Ash Uniformity Requirement of Fly Ash Blaine's fineness Particles retained on 45 µ sieve Lime reactivity 28-day Compressive strength 320 m 2 /kg (min) 34% (max) 4.5 MPa (min) Not less than 80% of control Variation in Fly Ash Quality % retained on 45 micron sieve IS 3812 requirement

54 Dominant Grades of Concrete supplied by major RMC Players

55 Customer Specified Mixes: Some Examples

56 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 * Not specified Not specified (25%) 400* NCR Not specified Not specified * Not specified Not specified (24%) 380* Goa Not specified Not specified * Coastal Karnataka Not specified * Not specified Not specified (17%) 380* * IS 456 specifies minimum cementitious content of 300 kg and w/b= 0.50

57 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 * Not specified Not specified (9%) 400* NCR Not specified Not specified * Not specified Not specified (23%) 390* Goa Not specified Not specified * Coastal Karnataka Not specified * Not specified Not specified (11%) 430* * IS 456 specifies minimum cementitious content of 320 kg and w/b= 0.45

58 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 * Not specified Not specified (19%) 480* NCR Not specified Not specified (19%) 490* Not specified Not specified (17%) 438* Goa Not specified Not specified * Coastal Karnataka Not specified Not specified (19%) 480* Not specified Not specified * IS 456 specifies minimum cementitious content of 340 kg and w/b= 0.45

59 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

60 Two strong restraints in production Why cracks in my concrete? Min. cement content Max. fly ash content Customer RMC Producer

61 Need of the Hour Try to give the producer as much choice as possible. Clause of ISO 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

62 Improving Durability through Enhanced utilization of SCMs Code-specified Upper Limit on SCMs Pozzolanic materials like fly ash (conforming to IS 3812) Ground Granulated Blastfurnace Slag (conforming to IS 12089) 35% 70%

63 Typical HVFAC mix Grade of Concrete OPC, kg Fly Ash, kg Total Cementitious materials, kg w/b ratio Slump, mm M day 28-day 56-day 90-day Compressive strength day day 56 day 28 day

64 Other Examples of HVFAC Grade OPC, kg FA, kg Total Cementitious, kg w/b ratio Slump, mm M M day 28 day 56 day 90 day 7-day 28-day 56-day 90-day

65 Typical Triple Blend Concrete Grade of Concrete OPC, kg Fly Ash, kg GGBS, Kg Total Cementitious material, kg w/b ratio Slump, mm M day 28 day 56 day 90 day

66 Recent Changes in Durability Specifications of IRST and IRC

67 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

68 IRST Guidelines for HPC Cementitious content not less than 380 kg/m 3 and not more than 450 kg/m 3 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 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.

69 IRC 112: Durability Recommendations for 100 Year Service Life Exposure Condition Max. watercement ratio Min. cement content, kg/m 3 Minimum grade of concrete Minimum cover, mm Moderate M25 40 Severe M30 45 Very Severe M40 50 Extreme M45 75 Source: Code of Practice for Concrete Road Bridges, IRC

70 IRC 112: Durability Tests Suggested upper limits for 56-day RCPT value Exposure Class Additionally suggested tests Water permeability (DIN 1048) ISAT (BS1881-Part 5) Acceptance criteria To be arrived at prior to testing 56 days Severe 1500 Very severe 1200 Extreme 800 No permissible values suggested

71 Metro Rail Specifications Mumbai Metro: Durability Specifications Water Penetration Test (DIN 1048) RCPT value Not greater than 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) Drying Shrinkage Moisture Movement RCPT Value Not greater than 28-35day Not greater than 28day Not greater than 28day Not greater than day

72 Lab Data on RCPT & Compressive Strength

73 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

74 RCPT and Strength Data (OPC 350 kg/m 3 and w/c ratio = 0.50) RCPT Value, Coloumb % Replacement of OPC by Fly Ash 0 28-day RCPT 28-day Comp. strength 28-day RCPT Values and Compressive strength for different replacement levels of OPC by Fly Ash

75 RCPT and Strength Data (OPC 400 kg/m 3 and w/c ratio = 0.44) COmpressive strength, MPa % Replacement of OPC by Fly Ash 0 28-day Comp. strength 28-day RCPT 28-day RCPT Values and Compressive strength for different replacement levels of OPC by Fly Ash

76 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

77 Future Evolve Guidelines Document for specifying durability (on lines of ISO 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 , Concrete Part 1: Methods of specifying and guidance for the specifier * ISO , Concrete Part 2: Specification of constituent materials, production of concrete and conformity of concrete

78 Thank You!

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80 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