A Study on Alkali-Silica Reactivity of Recycled Sands Produced from Glass Wastes
Kazuyuki TORII, Ayanori SUGIYAMA, Hiroaki YAMATO and Kenta SAKAI
Abstract:In recycling the sand originally produced from glass waste as a fine aggregate for concrete mixture, their alkali-silica reactivity and alkali-leaching ability are very important from the view-points of the long-term stability of the recycled glass sand in concrete. In this study, the alkali-silica reactivity of four types of glass sands was comparatively investigated according to the chemical method, JIS A1145, and three types of mortar bar methods, JIS A1146, ASTM C1260 and Danish method. Also, the amounts of the alkali ions, Na+ and K+, released from the sand itself in the saturated calcium hydroxide solution at 38 was periodically measured. From the results of experiment, it was found out that the alkali-silica reactivity of recycled glass sands could not be properly determined by the chemical method because of relatively large amounts of alkali ions released from the sand itself during the test, and that the expansion behavior of mortar bars in accelerated curing conditions significantly changed depending on both the chemical compositions and the internal texture of glass sands used. Finally, the mitigation method of alkali-silica reaction by using fly ash or glass powder was discussed. Key Words:Recycling, Glass waste, Alkali-silica reactivity, Alkali-leaching ability, Fly ash