Chapter 1 Introduction

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1.1 OVERVIEW

Alkali-silica reaction (ASR) is a major durability problem that has resulted in premature deterioration of various types of concrete structures in the United States and throughout the world. Although the use of lithium compounds has been known to be effective in controlling ASR-induced expansion for about 50 years, there have been only limited field applications. In the past 10 years, however, there has been renewed interest in using lithium as either an admixture in new concrete or as a treatment for existing structures. Because of the limited use of lithium compounds in laboratory research and field applications, guidelines have been lacking. This report presents guidelines and recommendations to provide practitioners with the required tools to test, specify, and use lithium compounds in concrete construction and repair applications.

1.2 ORGANIZATION OF REPORT

This report is organized in seven chapters, including this brief introductory chapter. Major topics are summarized below.

Chapter 2 provides a basic overview of ASR, including information on mechanisms, symptoms of ASR damage in field structures, mitigation approaches, test methods, and specifications. This chapter provides the reader with sufficient technical background on ASR, which is essential in understanding how lithium compounds affect the process.

Chapter 3 summarizes basic information on lithium compounds, including their production and availability. This chapter presents a comprehensive review of laboratory research on using lithium compounds to control ASR-induced expansion, including discussions on the proposed mechanisms by which lithium salts suppress expansion. It also includes a brief discussion on specifications related to lithium usage as a concrete admixture.

Chapter 4 describes several major field applications of lithium compounds that minimize or prevent ASR-induced expansion in new concrete and that treat field structures already showing signs of distress due to ASR. Relevant information on materials, mixture proportions, supporting laboratory data (if applicable), and field performance is provided for the selected case studies.

Chapter 5 presents guidelines for using lithium compounds as an admixture in new concrete and as a method of treating existing structures suffering from ASR-induced damage. The guidelines are aimed at helping practitioners test, specify, and use lithium in concrete construction applications. The guidelines are based on a comprehensive review of past laboratory and field applications of lithium compounds and on a survey of relevant specifications.

Chapter 6 discusses the economic considerations of using lithium compounds in new concrete and to treat existing structures. This chapter presents various factors that should be taken into account when considering the use of lithium.

Chapter 7 summarizes some of the major conclusions from this report and identifies some technical and practical issues that should be considered for future laboratory studies and field applications.