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
Subject of Presentation General Introduction Standards and Codes Shotcrete Materials Requirements Cementing Materials Aggregates Mixing Water Chemical Admixtures Shotcrete Performance Requirements
Subject of Presentation (continued) Quality Control Testing Aggregates Batching and Supply (Plastic Shotcrete) Hardened Shotcrete
Shotcrete Quality Control Organizational Chart
New Underground Gold Mine in British Columbia
Portal at Decline into Underground Mine
Mobile Mass Batcher Unit Discharging into Ready-Mix Concrete Truck
Remixer Unit for Hauling Shotcrete Down Decline
Remixer Unit Discharging into Shotcrete Pump at Back of Shotcrete Sprayer
Remote Control Shotcrete Sprayer
Manipulator Arm on Remote Control Shotcrete Sprayer Shooting ASTM C1550 Round Test Panels
Ready for Shotcreting Underground
Drilling Face for next Round of Blasting Note Shotcrete with Bolts and Plates
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)
Standards and Codes ASTM C114 ASTM C642-82 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
Standards and Codes (continued) American Concrete Institute (ACI) ACI 506R-05 Guide to Shotcrete ACI 506.2-95 Specifications for Materials Proportioning and Application of Shotcrete Canadian Standards Association (CSA) CSA A23.1-04 Concrete Materials and Methods of Concrete Construction CSA A23.2-04 Methods of Test and Standard Practices for Concrete CSA A3001-03 Cementitious Materials for Use in Concrete
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
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 0.5 0.5 A23.2-5A Material finer than 80 µm 3.0 1.0 A23.2-13A Flat and elongated particles Procedure A, ratios 4:1-20 A23.2-23A Micro-Deval test 20 17 A23.2-29A Unconfined freeze-thaw test - 6 A23.2-16A Impact and abrasion loss - 50 A23.2-9A MgSO 4 soundness loss 16 12
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 FA1 100 95-100 80-100 50-90 25-65 10-35 2-10 0-3
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 100 85-100 10-30 0-10 0-5
Grading Limits for Combined Aggregates Sieve Size 14 mm 10 mm 5 mm 2.5 mm 1.25 630 µm 315 µm 160 µm 80 µm Total passing sieve, percentage by mass 100 90-100 70-85 50-70 35-55 20-35 8-20 2-10 0-3
Graph of ACI No. 1 & No. 2 Gradings 120 Percent Passing 100 80 60 40 20 ACI Gradation 1 Limits ACI Gradation 2 Limits Combined % Passing 0 0.08 0.16 0.315 0.63 1.25 2.5 5 10 14 Metric Sieve Size
Chemical Limits for Mixing Water Maximum Concentration In Mixing Water, ppm Chloride as Cl Sulphate as SO Alkalies as (Na 2 O + 0.658 K 2 O) Total solids by mass Limits 1000 3000 600 50,000 ASTM Test Method C114 C114 C114 C1603
Chemical Admixtures Water Reducing Admixtures Set Retarding or Hydration Controlling Admixtures Air Entraining Admixtures Set Accelerators Added at Nozzle
Fibres Steel Fibres: ASTM C1116 Type I and ASTM A 820 Synthetic Fibres: ASTM C1116 Type III
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 A23.2 14C 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 0.40 170 ±20 mm 10-30 o C 2-5 % 2 MPa 10MPa 30 MPa 40 MPa 9 % 18 % *
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)
ASTM C1018 and ASTM C1609 Beam Test
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
Flexural Toughness Performance Levels Morgan and Chen, 1995
Fibre Shotcrete Beam Tests ASTM C1609 Load vs Deflection Curve
ASTM C1550 Round Panel Test
ASTM C1550 Round Panel Test
Technical Report
Typical Shotcrete Mixture Design Material Mass per m 3 SSD Agg [kg] Density [kg/m 3 ] Volume [m 3 ] Cement Type GU 430 3150 0.1365 Silica Fume 45 2200 0.0205 Coarse Aggregate (10-2.5mm, SSD) 380 2744 0.1385 Fine Aggregate (SSD) 1310 2649 0.4945 Estimated Water, L 185 1000 0.1850 High Water Reducing Admixture, L 2.5 1000 0.0025 Hydration Controlling Admixture, L 1.2 1000 0.0012 Macro Synthetic Fibre 6.0 910 0.0066 Air Content: At Pump (+/- 1.5%) 2.5 - - At Shot (%) 2.0-0.0202 Total 2354 Yield (m3) = 1.0105
Shotcrete Quality Control Certification and Testing Aggregates Batch Plant Mixers Plastic Shotcrete Hardened Shotcrete
Shotcrete Aggregates Testing Frequency CSA Test Method A23.2-3A A23.2-4A A23.2-5A A23.2-13A A23.2-23A A23.2-24A A23.2-16A A23.2-9A A23.2-15 A23.2-25A A23.2-2A A23.2-6A A23.2-7A A23.2-12A A23.2-11A 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
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
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
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
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
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