Evaluation of Use of Lithium Nitrate in Controlling Alkali-Silica Reactivity in Existing Concrete Pavement

The study presents the findings from a 2-year field trial in which lithium nitrate was applied at a rate of 0.006 gal/ft² twice a year on an existing concrete pavement in Norfolk, Nebraska, in an attempt to arrest ongoing alkali–silica reaction (ASR) distress. Various destructive and nondestructive means were used to measure the effectiveness of the treatments. Concrete cylinders were cored for petrographic examination and split tension testing. Powder samples were taken to determine the lithium content. Nondestructive evaluations used crack mapping, a Schmidt hammer, a velocity meter, and an impact echo apparatus. The amount of lithium that penetrated into the pavement by gravity soaking has been limited. The results to date have not shown a definitive benefit of application of the lithium material in controlling or mitigating the ASR process; presumably, the pavement has not reached the state of deterioration optimal for lithium penetration. The feasibility and effectiveness of other application techniques on hardened concrete, such as electrolysis, surface pressurization, and vacuum impregnation, should be investigated for comparison with the feasibility and effectiveness of gravity soaking.