Shotcrete

Materials, Performance and Use

Dudley Robert Morgan, Marc Jolin

• Publisher: CRC Press
• Year: 2022
• ISBN:
  9780429529863
• Edition: 1
• Topic: Technology & Engineering
• Subtopic: Construction & Architectural Engineering
• Index: Technology & Engineering

Shotcrete: Materials, Performance and Use is a comprehensive textbook covering the current state-of-the-art shotcrete technology. It provides an overview of the many and various uses of shotcrete. Shotcrete is well suited for construction of curvilinear structures (domes, shells, bobsleigh/luge tracks, etc.) and overhead shotcrete applications (seismic retrofit, repairs, ground support, etc.) that could not be constructed technically and/or economically using conventional formed, cast-in-place concrete construction methods.

It contains chapters on history, shotcrete materials and mixture proportioning, performance, shotcrete research, equipment and shotcrete application. It is also comprised of shotcrete case history examples including buildings and structures, infrastructure repair and rehabilitation, ground support and shoring, underground support in tunnels and mines, swimming pools and spas, and, finally, architectural shotcrete.

This text should be of interest to design engineers and architects considering the use of the technology, as well as academics. It serves as a useful guide to contractors using shotcrete in one or more of its many and various applications.

Part I History, material, performances, research and development, equipment and applications

Chapter 1 Introduction

DOI: 10.1201/9780429169946-2

While shotcrete has been with us for over 100 years and there are literally thousands of publications on various aspects of shotcrete technology, unlike concrete technology, there is a surprising dearth of general textbooks on the subject. There are a number of comprehensive shotcrete publications written by technical committees, such as the American Concrete Institute ACI 506R Guide to Shotcrete,¹ EFNARC European Specification for Sprayed Concrete, and Australian Shotcrete Society, Shotcreting in Australia, publications. There is also a textbook edited by Simon Austin and Peter Robins, Sprayed Concrete, Properties, Design and Application (1995) in which, interestingly, what were then considered to be special shotcretes ² have now, for the most part, become mainstream.

In addition to the above-mentioned publications, there are also a number of topic-specific shotcrete publications, such as the book by Marc Vandewalle (1996) on Tunneling the World, which is primarily focused on the use of steel fibre-reinforced shotcrete in tunnels and the International Tunnelling and Underground Space Association ITA Working Group 12: Permanent Sprayed Concrete Linings (2020) publication. Also, since 1999, the American Shotcrete Association has published Shotcrete Magazine four times a year and with between five and eight feature articles per issue, it has contributed over 500 publications to the shotcrete literature between 1999 and 2021.

So, while there is a wealth of available information on various aspects of shotcrete technology, it is scattered throughout a wide range of documents, some of them not readily available to persons interested in some particular aspect of the technology. Also, there have been a number of advances in shotcrete technology since the Austin and Robins book was published in 1995. This was the impetus for this textbook: Shotcrete; Materials, Performance and Use. It is designed to be a comprehensive textbook, covering the current state-of-the-art of shotcrete technology and providing information on a broad spectrum of the many and various uses of shotcrete in industry. It contains 16 chapters, with a comprehensive reference list at the end of each chapter. In this way, the interested reader can delve into any particular topic in more detail by consulting the references of interest.

This Shotcrete Book is intended to be of interest not only to academics (undergraduate and graduate students and teachers) interested in learning more about the topic, but also to design engineers and architects considering use of the technology. It should also be useful as a guide to contractors using shotcrete to build structures or use it in one or more of its many and various applications. The reader will find some repetition of material between different chapters. This is intentional in order to make the book more reader-friendly, i.e. avoid having to keep being referred to other chapters to get specific details on any particular topic.

The book is divided into two parts. Part I is composed of nine chapters. It provides Shotcrete Definitions and Terminology and then a brief History of Shotcrete from 1907 to 2020. There are then chapters on Shotcrete Materials, Mixture Proportioning and Performance Requirements. This is followed by a chapter on Shotcrete Research and Development (mainly based on R&D work carried out at Université Laval in Quebec and the University of British Columbia over a three-decade period). The last chapter in Part I deals with Shotcrete Application.

Part II provides a broad overview of Shotcrete Uses and Case Histories. Included in the seven chapters in Part II are chapters on shotcrete use in: Buildings and Structures, Infrastructure Repair and Rehabilitation, Ground Support and Shoring, Underground Support in Tunnels, Shotcrete in Mining, Swimming Pools and Spas and Architectural Shotcrete. Part II provides a general overview of a wide spectrum of applications for this versatile construction material/method.

Notes

1. Dr. Morgan, the first author of this Shotcrete Book, was Secretary of the ACI 506 Shotcreting Committee for 25 years and the second author, Dr. Jolin, has been a member for over 20 years, and chair for 6 years, of the same committee.
2. Chapter 11 on the topic of special shotcretes in Austin and Robins (1995) was written by Dr. Morgan.

References

• ACI 506R. 2016. Guide to Shotcrete. American Concrete Institute.
• Austin, S. and Robins, P. 1995. Sprayed Concrete, Properties, Design and Application. Whittles Publishing Services. 382.
• Australian Shotcrete Society. 2010. Shotcreting in Australia. Concrete Society of Australia. Second ed. 84.
• EFNARC. 1999. Guidelines for Specifiers and Contractors. European Specification for Sprayed Concrete. 31.
• ITA Working Group no 12 and ITAtech. 2020. Permanent Sprayed Concrete Linings. International Tunnelling and Underground Space Association. 56.
• Vandewalle, M. 1996. Tunneling the World. Zwevegem, Belgium, N.V. Bekaert, S.A. Fourth ed..

Chapter 2 Shotcrete definitions and terminology

DOI: 10.1201/9780429169946-3

2.1 What is shotcrete?

The American Concrete Institute CT-18 ACI Concrete Terminology defines shotcrete as follows: “concrete placed by a high velocity pneumatic projection from a nozzle”. The ACI 506.2–13(18) “Specification for Shotcrete” is a bit more specific and defines shotcrete as follows: “concrete or mortar conveyed through a hose and pneumatically projected at high velocity onto a surface to achieve compaction”. The American Shotcrete Association defines shotcrete as “a method of placing concrete with sufficient velocity to achieve compaction”.

In Europe and some other parts of the world, the term Sprayed Concrete rather than Shotcrete is used to describe the process. For example, the EFNARC “European Specification for Sprayed Concrete” (1996) uses the term Sprayed Concrete, rather than Shotcrete and defines Sprayed Concrete as “a mixture of cement, aggregate and water projected pneumatically from a nozzle into place to produce a dense homogeneous mass. Sprayed concrete normally incorporates admixtures and may also include additions of fibres or a combination of these”.

The above definitions all describe the same process, albeit with varying terminology and detail in description of the process. For the purpose of this book, however, the authors have elected to use the term Shotcrete to describe the process, as much of the content of this book is based on North American practice and experience. It should also be noted that depending on the context, the term Shotcrete is used in North America and elsewhere as both a noun and a verb, as it is used to describe both the material and the process of application of the material. It will be used interchangeably in this manner throughout this book.

2.2 Shotcrete processes

There are basically two different shotcrete processes: the wet-mix and the dry-mix processes. Wet-mix shotcrete is a process in which all of the ingredients, including water, are mixed before introduction into the delivery hose and compressed air is introduced to the material flow at the nozzle. Dry-mix shotcrete is a process in which most of the mixing water is added at the nozzle. It should be noted that the term “Gunite” is sometimes used in parts of North America and elsewhere in the world in lieu of dry-mix shotcrete. The reasons for this are discussed in Chapter 3. The term dry-mix shotcrete, rather than gunite will, however, be used throughout this book, as it is the term recommended for use for this process by the American Concrete Institute and American Shotcrete Association, as well as other organizations in North America.

The corresponding terminology used in the EFNARC “European Specification for Sprayed Concrete” is “Wet-Mix Sprayed Concrete” and “Dry-Mix Sprayed Concrete”. This specification describes the wet-mix process as follows:

a technique in which cement, aggregate and water are batched and mixed together prior to being fed into a purpose-made machine and conveyed through a pipeline to a nozzle where the mixture is pneumatically and continuously projected into place. The mixture normally incorporates admixtures and may also include additions of fibe...

Table of contents

• Cover Page
• Half Title Page
• Series Page
• Title Page
• Copyright Page
• Dedication
• Contents
• Preface
• Acknowledgements
• Authors
• Part I History, materials, performance, research and development, equipment and applications
• Part II Shotcrete uses and case histories
• Appendix A Guide specification for structural shotcrete
• Index