U.S. Department of Transportation
Federal Highway Administration
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Federal Highway Administration Research and Technology
Coordinating, Developing, and Delivering Highway Transportation Innovations
|This report is an archived publication and may contain dated technical, contact, and link information|
Publication Number: FHWA-HRT-06-073
Date: July 2006
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 potential for lithium compounds to control ASR-induced expansion has been known for about 50 years, there have been limited field applications with even less comprehensive performance monitoring. 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 of existing structures. Because of the limited use of lithium compounds in laboratory research and field applications, guidelines have been lacking. This report presents recommendations for practitioners to test, specify, and use lithium compounds in concrete construction and repair applications.
This report replaces the previously published lithium guideline report (Guidelines for the Use of Lithium to Mitigate or Prevent Alkali-Silica Reaction (ASR), Folliard, et al., 2003). Substantial changes have been made, and the recommendations provided within the current document should be considered to be the most relevant and applicable to future applications of lithium. The following highlights some of the key modifications and revisions made to the current guideline document:
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. The main objective of this chapter is to provide 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 additives suppress expansion. It also includes a brief discussion on specifications related to lithium usage as an admixture in new concrete.
Chapter 4 describes several major field applications of lithium compounds aimed to 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 recommendations for using lithium compounds as an admixture in new concrete and as a method of treating existing structures suffering from ASR-induced damage. The recommendations are aimed at helping practitioners test, specify, and use lithium in concrete construction applications. The guidelines are based on a comprehensive review of 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.