A novel assessment of the electrochemical lithium impregnation treatment used to mitigate alkali-silica reaction in concrete

Lithium compounds are used to prevent alkali–silica reaction (ASR) in concrete. If lithium is mixed in wet concrete, the swelling effects of ASR are mitigated. Electrochemical lithium impregnation techniques have been also used successfully on a number of older structures. This paper evaluates the electrochemical penetra-tion and ASR performance of lithium in hardened concrete. Reactive Colombian aggregate and commercial cement were used to prepare mortar mixes and lithium nitrate performance was evaluated using the accelerat-ed ASTM C1260 Mortar-Bar Method. Two penetration methods were used to introduce lithium into concrete. First, concrete was mixed with lithium in the mix water and expansion was measured using ASTM C1260. Second, lithium ions were migrated into ASTM 1260 mortar bars using an electric field.
A novel experimental method was developed for electrochemical treatment and assessment of the mortar bars. Samples were cast in ASTM C490 molds used in determining the length change of mortar bars (25 x 25 x 250mm). Stainless steel electrodes were used in the migration cells, which were filled using 0.3M KOH + 0.1M NaOH in the cathode reservoir and 30% LiNO3 in the anode reservoir. Voltages of 15 and 20 Volts were applied for 4 days. After electrochemical treatment, samples were tested to ASTM C1260. Compressive strength tests were carried out to determine the effects of lithium. Results indicate that lithium significantly mitigates the reactivity of aggregate and the ionic lithium migration seems to be more effective than initial mixing.