Effect Of The Substance Containing Aluminium On Alkali-Silica Reaction

Alkali-aggregate reaction (AAR) is one of the most important factors that cause concrete losing its durability and usable value too early as well as cutting down its life. Alkali silica reaction (ASR) is the most important and universal type of AAR and it has been a hot topic in area of AAR study to avoid ASR expansion. In this paper, the effect of several substances containing aluminum on alkali-silica reaction and mechanism were investigated.Quartz glass was used for the alkali reactive aggregate. By ultra-accelerated mortar-bar test, the effects of several substances containing aluminum (including active alumina admixture,aluminum hydroxide,aluminum sulfate,aluminum nitrate and rectified aluminum nitrate) on alkali-silica reaction were tested. Combined with XRD and SEM, the reasons of aluminum on alkali-silica reaction were investigated. Active alumina admixture was obtained by burning bauxite. The results showed that alkali- silica reaction can be inhibited when the replacement of cement by active alumina and aluminum hydroxide, but can not be inhibited by aluminum sulfate and aluminum nitrate. The inhibiting mechanism of the substances containing aluminum on ASR was discussed from the content of available alkali,the effect of C-S-H that Al3+ ions were solid dissolved in on adsorption ability for alkali ions and the effect of products, the results were gotten:The content of available alkali of pore solution was reduced by active alumina. The content of available alkali was less when it had more active alumina admixture. The content of available alkali initially decreased and then increased with increasing aluminum hydroxide.The adsorption ability for Na+ ions of C-S-H gel that Al3+ ions were solid solution in was enhanced. And the adsorption ability of C-S-H gel was affected by the molar ratio of Al/Si. The adsorption content for Na+ ions of C-S-H was the top when the molar ratio of Al/Si is certain. The adsorption content for Na+ ions of C-S-H was increasing with time.The alkali-silica reaction products were altered. The products trended to become crystal substance. Zeolite was found when quartz glass was marinated in alkali solution containing aluminum.