Investigation of the influence of curing temperature and silica fume content on setting and hardening process of the blended cement paste by an improved ultrasonic apparatus

An ultrasonic measurement apparatus (UMA) was developed for in situ continuously monitoring the early age hydration process of cementitious material. Utilizing UMA, the influence of curing temperature and silica fume content on the setting and hardening process of the low water to binder ratio cementitious material were systematically investigated. The experimental results show that setting and hardening process of the silica fume blended cement paste at elevated temperature can be clearly identified into three stages including dormant stage, acceleration stage and deceleration stage. Besides, the increasing of curing temperature and silica fume content greatly accelerate the setting and hardening process of silica fume blended cement paste and increase the ultimate ultrasonic pulse velocity. To aid in comparing with the ultrasonic results, the isothermal calorimetric measurement, Vicat needle test and mechanical properties test were also conducted.

► A new ultrasonic measurement apparatus was specially designed.
► Temperature and silica fume content on setting process of cement were investigated.
► The setting and hardening process can be clearly identified into three stages.
► Initial and final setting time are greatly reduced by elevated temperature and addition of silica fume.