INSIDE THE DOT
South Dakota Department of Transportation
Use of Lithium to Prevent ASR
Dan Johnston, SDDOT
1/1/1900 - 1/1/1900
Since 1980 alkali-silica reactivity (ASR) has become an increasingly critical concern with regards to the durability of concrete pavements and structures in South Dakota. The first pavement to exhibit severe ASR was a 38 mile section of I-90 in Lyman County built in 1972. The pavement has continued to deteriorate and become a significant maintenance problem remaining serviceable only due to the presence of the reinforcing. To combat potential problems with ASR in future construction SDDOT adopted the use of Type II, Low Alkali cement in 1983. Contemporary wisdom contended that the use of portland cement with an equivalent alkali content less than 0.6% would eliminate ASR in concrete even if an aggregate source was deleteriously reactive. Unfortunately, confidence in the assumption has been gradually eroded by the discovery of certain aggregates, mostly volcanic in origin, which undergo ASR even in the presence of a low alkali cement and by the growing awareness of deicing salts as an external source of alkali. Since 1983 numerous pavements statewide have exhibited various degrees of ASR. In addition, Sioux quartzite, the premiere coarse aggregate used in eastern South Dakota, has proven to be slowly reactive. The impact of ASR on concrete durability and pavement life and the need to evaluate aggregate sources and develop strategies to minimize the risk of premature deterioration of PCC pavements prompted this research. Because the use of lithium salts is a recognized method of mitigating potential ASR, and because there is a need to verify the results of the Strategic Highway Research Program research on ASR, both laboratory and field testing are necessary.
1 Verify the SHRP laboratory test results using lithium and fly ash with reactive and nonreactive aggregate.
2 Monitor the effectiveness of various treatments at mitigating ASR in both new and existing concrete.
1 Review literature pertinent to ASR and its prevention with fly ash and lithium.
2 Conduct laboratory tests using AASHTO TP14 to confirm the results of the SHRP work using two reactive aggregate and one nonreactive aggregate with various combinations of lithium hydroxide, C and F fly ashes and a Type IP cement.
3 Construct PCC test sections incorporating various experimental combinations of cement, lithium and fly ash into concrete containing aggregate which is susceptible to ASR.
4 Treat an existing ASR-deteriorated pavement with lithium.
5 Monitor all test sections semi-annually for the first two years and annually for five years.
6 Instrument selected test sections with vibrating wire strain gauges near joints to characterize stress buildup due to expansion prior to ASR-induced cracking.
7 Obtain cores from each test section for petrographic and physical testing as needed.
8 Conduct Falling Weight Deflectometer and Impact Echo testing on all test sections.
9 Provide construction and annual evaluation reports.
10 Provide a final report and executive summary detailing a literature summary, research methodology, conclusions and recommendations.
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