jailcd2019-048: A Study on Pozzolanic Reaction and Strength Development of Mortar Using Modified Fly Ash by Changed Curing Temperature

Abstract

Using  fly ash which  is  an  industrial byproduct  of coal  fired power plants  as  admixture  for  concrete  can contribute to environmental load reduction and concrete quality improvement. However, as the quality of fly ash fluctuates depending on the ash source, quality stabilization is required. Therefore, expanding use fly ash we studied  development  of quality  stabilization  technology  for  improving  the  quality  by  flotation  method,  and developed the unburned carbon removing device. And now it has been clarifed that concrete with fly ash of Japanese Industrial Standardized class II has different strength properties depending on curing temperature, but it is not  obvious  whether  concrete  with  modified  fly  ash  by  flotation  method  is  simila.  In  this  study,it  was examined about the influence on strength development and pozzolanic reaction when changing the curing temperature of mortar using fly ash modified by flotation method.The sealing curing was set to 20°C.40°C and 60°C. the measurement items are compression strength,pozzolanic reaction parcentages,and Calcium hydroxide amount．As for the amount of calcium hydroxide, the modified fly ash showed a higher production amount than the origin ash.The higher the curing temperature, the higher the pozzolan reaction rate of the modified fly ash was, and no significant difference was found between the reaction rate of the origin ash.The mortar mixed with the modified fly ash had a calcium hydroxide content higher than that of the origin ash at the age of 28 days.The possibility that strength improvement by pozzolan reaction will proceed even after 91 days of age is revealed.