Concrete expansion due to alkali-silica reaction (ASR) is one of the serious deterioration mechanisms of concrete structures. However, no promising repair method for ASR has been established yet. In a bid to remedy this situation, an electrochemical technique to accelerate the penetration of the lithium ions (Li + ) in a lithium-based electrolyte solution into concrete has been developed for the purpose of suppressing ASR-induced expansion due to Li + . From the results of past research work, the penetration area of Li + is limited around the concrete surface and it is difficult to make Li + penetrate into the deeper part of concrete. In this study, experimental investigation was carried out aiming to grasp the influence of the kinds of lithium salts and the temperature of the electrolyte solution on the migration properties of ions in concrete and ASR-induced expansion of concrete. The electrochemical migration of Li + was found to accelerate with rises in temperature and the effective diffusion coefficient of Li + increased three times with changes in temperature from 20˚C to 40˚C in the case of a Li 2 CO 3 electrolyte solution. Moreover, ASR-induced expansion of concrete after this treatment was suppressed compared with the case of non-treated specimens.
The purpose of this study was to investigate the influence of phosphoric acid etching, metal primer or silane coupling agent application on dentin bonding performance of a 2-step self-etch adhesive system. Human dentin surfaces were prepared and divided into four groups depending on the pre-treatment method: no pretreatment (Clearfil SE Bond 2, CONTROL); 40% phosphoric acid (K-Etchant GEL, K); metal primer (Alloy Primer, AP); or silane coupling agent (Porcelain Bond Activator, PB). The specimens were sectioned into beams, separated into 2 subgroups (n=20): no thermocyling or thermocycled (TC), and subjected to a µTBS test and an acid-base challenge for SEM observation. Statistically lower results were observed between K and AP groups, PB and CONTROL, and PB with/ without TC (p<0.05). SEM images at the dentin-adhesive interface revealed that all groups produced an acid-base resistant zone (ABRZ), with a funnel-shaped erosion under the ABRZ for the K group.
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