Shotcrete Quality Control and Testing for an Underground Mine in Canada

Transcription

1 Shotcrete Quality Control and Testing for an Underground Mine in Canada By Dudley R. (Rusty) Morgan and Mazin Ezzet AMEC Earth & Environmental, a division of AMEC Americas Limited SHOTCRETE FOR AFRICA CONFERENCE Misty Hills Conference Centre South Africa 2-3 March, 2009

2 Subject of Presentation General Introduction Standards and Codes Shotcrete Materials Requirements Cementing Materials Aggregates Mixing Water Chemical Admixtures Shotcrete Performance Requirements

3 Subject of Presentation (continued) Quality Control Testing Aggregates Batching and Supply (Plastic Shotcrete) Hardened Shotcrete

4 Shotcrete Quality Control Organizational Chart

5 New Underground Gold Mine in British Columbia

6 Portal at Decline into Underground Mine

7 Mobile Mass Batcher Unit Discharging into Ready-Mix Concrete Truck

8 Remixer Unit for Hauling Shotcrete Down Decline

9 Remixer Unit Discharging into Shotcrete Pump at Back of Shotcrete Sprayer

10 Remote Control Shotcrete Sprayer

11 Manipulator Arm on Remote Control Shotcrete Sprayer Shooting ASTM C1550 Round Test Panels

12 Ready for Shotcreting Underground

13 Drilling Face for next Round of Blasting Note Shotcrete with Bolts and Plates

14 Standards and Codes American Concrete Institute (ACI) American Society for Testing and Materials (ASTM) Canadian Standards Association (CSA) National Ready Mix Concrete Association (NRMCA) Concrete Plant Manufacturer s Bureau (CPMP)

15 Standards and Codes ASTM C114 ASTM C ASTM C1116 ASTM C1140 ASTM C1141 ASTM C1436 ASTM C1550 ASTM C1602 ASTM C1604 Standard Test Methods for Chemical Analysis of Hydraulic Cements Standard Test Method for Specific Gravity, Absorption, and Voids in Hardened Concrete Specification for Fibre Reinforced Concrete Standard Practice for Preparing and Testing Specimens from Shotcrete Test Panels Specification for Admixtures for Shotcrete Standard Specification for Materials for Shotcrete Standard Specification for Flexural Toughness of Fibre Reinforced Concrete (Using Centrally Loaded Round Panel) Standard Specification for Mixing Water Used in Production of Hydraulic Cement Concrete Standard Test Method for Obtaining and Testing Drilled Cores of Shotcrete

16 Standards and Codes (continued) American Concrete Institute (ACI) ACI 506R-05 Guide to Shotcrete ACI Specifications for Materials Proportioning and Application of Shotcrete Canadian Standards Association (CSA) CSA A Concrete Materials and Methods of Concrete Construction CSA A Methods of Test and Standard Practices for Concrete CSA A Cementitious Materials for Use in Concrete

17 Shotcrete Materials Cementing Materials Portland Cement: CSA Type GU Fly Ash: CSA Type F or CI Silica Fume: CSA Type SF Other Cementing Materials Natural Pozzolans Calcined Metakaolins Ground Granulated Blast Furnace Slag

18 Limits for Deleterious Substances and Physical Properties of Aggregates CSA Test Method A23.2-3A Property Standard Requirements Clay lumps Maximum Percentage by Mass of Total Sample Fine Aggregate 1 Coarse Aggregate 0.25 A23.2-4A Low-density granular materials A23.2-5A Material finer than 80 µm A A Flat and elongated particles Procedure A, ratios 4:1-20 A A Micro-Deval test A A Unconfined freeze-thaw test - 6 A A Impact and abrasion loss - 50 A23.2-9A MgSO 4 soundness loss 16 12

19 Grading Limits for Fine Aggregate Total Passing Sieve, Percentage by Mass Sieve Size 10 mm 5 mm 2.5 mm 1.25 mm 630 µm 315 µm 160 µm 80 µm FA

20 Grading Limits for Coarse Aggregate Nominal Size of Aggregate 14 mm 10 mm 5 mm 2.5 mm 1.25 mm Total Passing Sieve, Percentage by Mass

21 Grading Limits for Combined Aggregates Sieve Size 14 mm 10 mm 5 mm 2.5 mm µm 315 µm 160 µm 80 µm Total passing sieve, percentage by mass

22 Graph of ACI No. 1 & No. 2 Gradings 120 Percent Passing ACI Gradation 1 Limits ACI Gradation 2 Limits Combined % Passing Metric Sieve Size

23 Chemical Limits for Mixing Water Maximum Concentration In Mixing Water, ppm Chloride as Cl Sulphate as SO Alkalies as (Na 2 O K 2 O) Total solids by mass Limits ,000 ASTM Test Method C114 C114 C114 C1603

24 Chemical Admixtures Water Reducing Admixtures Set Retarding or Hydration Controlling Admixtures Air Entraining Admixtures Set Accelerators Added at Nozzle

25 Fibres Steel Fibres: ASTM C1116 Type I and ASTM A 820 Synthetic Fibres: ASTM C1116 Type III

26 Typical Shotcrete Performance Requirements Test Method - CSA A23.2 5C - CSA A23.2 4C Penetrometer as calibrated against beams tested as equivalent cubes ASTM C1604 & CSA A C ASTM C642 ASTM C1550 Air content as shot Property Maximum water/cementing materials ratio Slump (at discharge into shotcrete pump) Temperature (at discharge into shotcrete pump) Minimum early age compressive strength before re-entry under shotcrete Minimum compressive strength of shotcrete cores 1 Day 7 Days 28 Days Maximum values of boiled absorption Maximum volume of permeable voids Minimum Joules energy at 40 mm deflection in round panel test Performance Requirement ±20 mm o C 2-5 % 2 MPa 10MPa 30 MPa 40 MPa 9 % 18 % *

27 Fibre Reinforced Shotcrete Testing in North America Steel fibre synthetic macro-fibre reinforced shotcrete in North America has been tested to the following ASTM Standards: ASTM C1018: Standard test method for flexural toughness and first-crack strength of fiber-reinforced concrete (using beam with third point loading) first published 1984, withdrawn 2006 ASTM C1609: Standard test method for flexural performance of fiber-reinforced concrete (using beam with third point loading) first published 2005 ASTM C1550: Standard test method for flexural toughness of fiber reinforced concrete (using centrally loaded round panel)

28 ASTM C1018 and ASTM C1609 Beam Test

29 Fibre Shotcrete Tests ASTM C1018 Load vs Deflection Curve Test Results Include: First crack and ultimate flexural strengths (MPa) Toughness Indices I 5, I 10, I 20, etc Residual Strength Factors R 5, 10, R 10, 20, etc. Problems of reliability with this test method and withdrawn in 2006

30 Flexural Toughness Performance Levels Morgan and Chen, 1995

31 Fibre Shotcrete Beam Tests ASTM C1609 Load vs Deflection Curve

32 ASTM C1550 Round Panel Test

33 ASTM C1550 Round Panel Test

34 Technical Report

35 Typical Shotcrete Mixture Design Material Mass per m 3 SSD Agg [kg] Density [kg/m 3 ] Volume [m 3 ] Cement Type GU Silica Fume Coarse Aggregate (10-2.5mm, SSD) Fine Aggregate (SSD) Estimated Water, L High Water Reducing Admixture, L Hydration Controlling Admixture, L Macro Synthetic Fibre Air Content: At Pump (+/- 1.5%) At Shot (%) Total 2354 Yield (m3) =

36 Shotcrete Quality Control Certification and Testing Aggregates Batch Plant Mixers Plastic Shotcrete Hardened Shotcrete

37 Shotcrete Aggregates Testing Frequency CSA Test Method A23.2-3A A23.2-4A A23.2-5A A A A A A A A A A23.2-9A A A A A23.2-2A A23.2-6A A23.2-7A A A A A Property Clay Lumps Low Density Granular Materials Material Finer than 80 µm Flat and Elongated Particles Micro-Deval Test Unconfined Freeze-thaw Test Impact and Abrasion Loss MgSO 4 Soundness Loss Petrographic Analysis Alkali Silica Reactivity Sieve Analysis of Fine and Coarse Aggregates Relative Density and Absorption of Fine Aggregates Organic Impurities Colour Test Relative Density and Absorption of Coarse Aggregate Surface Moisture in Fine and Coarse Aggregates Testing Frequency 6 months 6 months 1 week 6 months 6 months 6 months 6 months 6 months 1 year 1 year Each delivery 6 months 1 week 6 months Each day

38 Shotcrete Batching and Supply Certification and Testing Test Method Test Procedure Testing Frequency NRMCA CPMB 100 M-07 Certification of ready mixed concrete production facilities using truck mixing At start of project and every 2 years NRMCA CPMB 100 M-07 Certification of ready mix concrete truck mixers and remixer units Before use and every 6 months NRMCA CPMB 100 M-07 Batch records with solid materials in kg and liquids in L Each batch of shotcrete produced

39 Plastic Shotcrete QC Testing Test Method CSA A23.2-5C CSA A23.2-5C CSA A23.2-7C CSA A23.2-7C Modified CSA A23.2-7C Modified Test Procedure Slump at discharge into remixer unit Slump at discharge into shotcrete pump Shotcrete and ambient temperatures at discharge into remixer unit and at shotcrete pump Air content of plastic shotcrete at discharge into remixer unit and at shotcrete pump Air Content as-shot (without accelerator) Wash-out test to determine uniformity of fibre distribution at discharge from remixer unit Testing Frequency Each batch of shotcrete produced At beginning of each shift Each batch of shotcrete produced At start of project and with any change in mixture proportions At start of project and with any change of mixture proportions At start of project and with any change in fibre type or dosage

40 Hardened Shotcrete QC Testing Test Method Ref. 1 Penetrometer ASTM C1140 ASTM C1604 ASTM C642 ASTM C1550 ASTM C1550 Test Description Early age compressive strength of beams as equivalent cubes Early age compressive strength estimate using penetrometer Compressive strength of cores extracted from shotcrete test panel at age 1 day (1 core), 7 days (1 core) and 28 days (2 cores) Boiled absorption and volume of permeable voids Round panel test to 40mm deflection Round panel test to 40 mm deflection Testing Frequency At start of project and with any change in mixture proportions or accelerator type or dosage One heading per shift One heading per week for each shotcrete robot and each shotcrete crew used One heading per week for each shotcrete robot used Two panels at each of ages 7 and 28 days at start of project for one fibre type and dosage Two panels at 28 days for each week of shotcrete production or at any change in fibre type or dosage

41 Quality Assurance Plan Shotcrete Quality Control Shotcrete Materials Check List Inspection and Test Plan (ITP) a) Materials b) Batching and Supply c) Hardened Shotcrete Shotcrete Quality Audit Non-conformance Report (NCR) Opportunity for Improvement Report (OFI) Corrective Action Report (CAR) Audit Report

42 Conclusions Production of quality shotcrete in an underground environment requires: Rigorous shotcrete specifications Implementation of a quality management plan (follow ISO 9000 approach) Pre-production qualification of all materials and shotcrete mixture design Implementation of a systematic quality control inspection and testing plan for the aggregates, mix water and plastic and hardened shotcrete Use of nozzlemen and shotcrete batching, supply and application crew properly trained and qualified