Efflorescence formation and control in alkali-activated phosphorus slag cement

Efflorescence formation is an important soundness issue to be considered with alkali-activated cements. in this study,the impact of activator type on the efflorescence formation severity and methods of efflorescence reduction in alkali-activated phosphorus slag cement are investigated. different alkaline activators including naoh,koh and liquid sodium silicate of different silica modules (ms = sio2/na2o) were used for alkali-activation of phosphorus slag. additions of high alumina cements (secar 71 and 80) and application of hydrothermal curing condition at 85 °c for 7 h with different pre-curing times (1,3 and 7 days) in humid environment (relative humidity of 95 %) and 25 °c were used for efflorescence control in alkali-activated phosphorus slag cement. sodium containing activators resulted in more severe efflorescence formation compared with those of potassium containing activators. also presence of liquid sodium silicate intensified efflorescence formation. based on the results obtained,application of an optimum pre-curing stage in humid environment before hydrothermal curing regime stabilizes the cement matrix and improves the effectiveness of hydrothermal conditions. © iran university of science and technology 2016.