Journal Published Online: 20 September 2022
Volume 51, Issue 2

Optimization of Parameters of the New Turner-Fairbank Alkali-Silica Reactivity Susceptibility Test (T-Fast)

CODEN: JTEVAB

Abstract

Prevention is an effective strategy to avoid damage caused by the alkali-silica reaction (ASR) in concrete structures. The effectiveness of this strategy heavily depends on the use of reliable accelerated tests to determine if an aggregate used in the concrete has the potential to cause ASR. Recently, a new provisional standard test, AASHTO TP 144-21, Determining the Potential Alkali–Silica Reactivity of Coarse Aggregates (TFHRC-TFAST), has been approved by the American Association of State Highway and Transportation Officials. The test accurately predicted the ASR-induced expansion of aggregates used in more than 50 different mortar and concrete samples, including concrete blocks in outdoor testing facilities and concrete in the field. This manuscript presents the results of the collaborative study among three laboratories conducted as part of an overall effort to standardize the new AASHTO TP 144-21. The objectives of the study were to evaluate the suitability of wavelength dispersive x-ray fluorescence (WDXRF) spectroscopy as the main analytical technique, determine the optimal particle size and effect of moisture on calcium oxide (CaO), and evaluate sample preparation on the results. A total of 18 aggregates were evaluated under the TP 144-21 using 4 different CaO samples and 2 sample preparation protocols. The results indicated that the alkali-silica reactivity of the aggregates can be accurately determined by using WDXRF. Upon exposure to the atmosphere, CaO reacts rapidly with moisture to produce calcium hydroxide [Ca(OH)2]. The particle size distribution and amount of Ca(OH)2 in the CaO influenced the ASR classification of marginal (moderately and slow reactive) and nonreactive aggregates. The researchers obtained optimal results using a reagent grade powder CaO with an average particle size of 4.6 μm and less than 5 % of Ca(OH)2. These conclusions were important to validate and optimize the TP 144-21 protocol before launching a wider interlaboratory study.

Author Information

Muñoz, Jose F.
SES Group & Associates, LLC, Chemistry Laboratory, Turner-Fairbank Highway Research Center, McLean, VA, USA
Balachandran, Chandni
SES Group & Associates, LLC, Chemistry Laboratory, Turner-Fairbank Highway Research Center, McLean, VA, USA
Lichtenwalner, Ronald L.
Materials and Tests Unit, North Carolina Department of Transportation, Raleigh, NC, USA
Li, Zihui
Concrete Materials Testing Branch, Office of Central Laboratory, Division of Engineering Services, California Department of Transportation, Sacramento, CA, USA
Arnold, Terence S.
Chemistry Laboratory, Turner-Fairbank Highway Research Center, U.S. Department of Transportation, Federal Highway Administration, McLean, VA, USA
Pages: 16
Price: $25.00
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Stock #: JTE20220033
ISSN: 0090-3973
DOI: 10.1520/JTE20220033