Description

This document provides a guide for owners, contractors, designers, and testing, specifying, and inspection organizations engaged in the application of shotcrete for underground support. The guide provides general information for the selection of constituent materials, and methods to proportion shotcrete. Typical methods of batching, mixing, and handling of proportioned shotcrete materials are detailed along with shotcrete placement methods and equipment.

Keywords:

acceptance criteria; batching; inspection; methods of payment; mine(s); mixing; mixture proportioning; placement; quality assurance; quality control; safety; shotcrete; testing; tunneling.

Document Details

Author: ACI Committee 506

Publication Year: 2022

Pages: 61

ISBN: 9781641951982

Formats: Printed Document or Protected PDF/Web View

Table of Contents

CHAPTER 1—INTRODUCTION AND SCOPE, p. 3

1.1—Introduction, p. 3

1.2—Scope, p. 4

CHAPTER 2—NOTATION AND DEFINITIONS, p. 5

2.1—Notation, p. 5

2.2—Definitions, p. 5

CHAPTER 3—SUBMITTALS, p. 6

3.1—Submittal process, p. 6

3.2—Recommended specifications, p. 7

CHAPTER 4—MATERIALS, p. 7

4.1—Accelerators, p. 7

4.2—Recommended specifications, p. 8

CHAPTER 5—ANCHORAGE AND REINFORCEMENT, p. 10

5.1—Composite support systems, p. 10

5.2—Shotcrete with pattern rock bolts or anchors, p. 11

5.3—Shotcrete with rock bolts, friction stabilizers, and welded wire reinforcement, p. 11

5.4—Fiber-reinforced shotcrete, p. 12

5.5—Shotcrete with lattice girders, p. 13

5.6—Shotcrete with conventional steel sets, p. 14

5.7—Recommended specifications, p. 14

CHAPTER 6—MATERIALS HANDLING AND STORAGE, p. 15

6.1—General, p. 15

6.2—Temperature considerations, p. 15

6.3—Recommended specifications, p. 16

CHAPTER 7—SHOTCRETE MIXTURE PROPORTIONING, p. 16

7.1—General, p. 16

7.2—Mixture proportions by trial batching or historical data submissions, p. 16

7.3—In-place mixture proportions, p. 16

7.4—Dry-mix shotcrete, p. 17

7.5—Wet-mix shotcrete, p. 18

7.6—Recommended specifications, p. 20

CHAPTER 8—PERFORMANCE REQUIREMENTS, p. 20

8.1—General, p. 20

8.2—Water-cementitious materials ratio, p. 20

8.3—Air content, p. 20

8.4—Slump, p. 21

8.5—Boiled absorption and permeable voids, p. 21

8.6—Compressive strength, p. 21

8.7—Flexural strength and toughness, p. 21

8.8—Early-age strength, p. 21

8.9—Other tests, p. 22

8.10—Bond strength, p. 22

8.11—Fire-induced explosive spalling protection, p. 22

8.12—Recommended specifications, p. 22

CHAPTER 9—QUALITY ASSURANCE AND QUALITY CONTROL, p. 23

9.1—General, p. 23

9.2—Recommended specifications, p. 24

CHAPTER 10—PRECONSTRUCTION TRIALS AND TESTING, p. 24

10.1—General, p. 24

10.2—Recommended specifications, p. 24

CHAPTER 11—CONSTRUCTION ACCEPTANCE INSPECTION, p. 26

11.1—General, p. 26

11.2—Acceptance inspection, p. 26

11.3—Specific inspection and testing quality control requirements for underground shotcrete, p. 28

11.4—Cold placement conditions, p. 29

11.5—Hot placement conditions, p. 29

11.6—Shotcrete acceptance and rejection, p. 29

11.7—Recommended specifications, p. 30

11.8—Recommended QC Inspection and Testing Checklist, p. 32

CHAPTER 12—BATCHING, MIXING, AND SUPPLY, p. 33

12.1—Handling of bulk bin-bags, p. 33

12.2—Quality control considerations, p. 33

12.3—Recommended specifications, p. 33

CHAPTER 13—PLACING EQUIPMENT, p. 35

13.1—General, p. 35

13.2—Pumps for wet-mix, p. 35

13.3—Guns for dry-mix, p. 35

13.4—Nozzle systems, p. 36

13.5—Remote-controlled spraying, p. 36

13.6—Recommended specifications, p. 37

CHAPTER 14—AUXILIARY EQUIPMENT, p. 38

14.1—Air supply, p. 38

14.2—Recommended specifications, p. 39

CHAPTER 15—SAFETY, p. 40

15.1—General, p. 40

15.2—Underground safety, p. 40

15.3—Required personal safety equipment, p. 40

15.4—View of shotcrete work, p. 41

15.5—Communications, p. 41

15.6—Nonpersonal safety equipment, p. 42

15.7—Recommended specifications, p. 42

CHAPTER 16—PREPARATION FOR SHOTCRETING AND GROUNDWATER CONTROL, p. 43

16.1—General, p. 43

16.2—Factors affecting shotcrete adhesion and bonding, p. 43

16.3—Surface preparation, p. 44

16.4—Groundwater, p. 44

16.5—Recommended specifications, p. 45

CHAPTER 17—GROUND REINFORCEMENT INSTALLATION, p. 46

17.1—General, p. 46

17.2—Rock bolt installation, p. 46

17.3—Steel set installation, p. 46

17.4—Lattice girder installation, p. 46

17.5—Face support, p. 47

17.6—Recommended specifications, p. 47

CHAPTER 18—SHOTCRETE APPLICATION, p. 47

18.1—Methods used to control thickness, p. 47

18.2—Cover, alignment, and tolerance, p. 47

18.3—Recommended specifications, p. 48

CHAPTER 19—CURING AND PROTECTION, p. 50

19.1—General, p. 50

19.2—Protection, p. 50

19.3—Recommended specifications, p. 51

CHAPTER 20—SHOTCRETE FOR REPAIR AND REHABILITATION OF UNDERGROUND STRUCTURES, p. 52

20.1—General, p. 52

20.2—Materials selection, p. 52

20.3—Shotcrete placement methods for repair, p. 53

20.4—Quality assurance requirements for rehabilitation of underground structures, p. 53

20.5—Repair considerations, p. 53

20.6—Recommended specifications, p. 54

CHAPTER 21—MEASUREMENT AND PAYMENT, p. 54

21.1—Basis for payment, p. 54

21.2—Recommended specifications, p. 55

CHAPTER 22—REFERENCES, p. 55

Authored documents, p. 56

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