RELATION BETWEEN MINERAL COMPOSITIONS OF FLY ASH AND ITS POZZOLANIC REACTION

OTSUKA Taku, MORI Shinichiro, ISHIKAWA Motoki, SAKAI Etsuo

doi:10.14250/cement.63.16

In this study, hydration properties of ordinary Portland cement（OPC）with 4 types of fly ash have been discussed. 4 types of fly ash were all classified into fly ash type II by JIS A 6201. Replacement ratio of FA to cement were 20 mass％. Water to powder ratio was 0.4 and samples were cured in bottles made of polystyrene at 20 and 40℃. The hydration was stopped after a prescribed time（3, 7, 31, 181, 365, 555 days）by mixing the sample with a large quantity of acetone. The Sample was dried in a vacuum for 24 hours. The reaction ratio of FA was determined by measuring unreacted fly ash using 2M HCl and 5％ Na₂CO₃ aqueous solution. The unreacted amount of α-quartz in fly ash was determined by X-ray diffraction using 10 mass％ α-alumina as the internal standard. The amount of Ca（OH）₂ was determined by measuring the mass loss between 405 and 515℃ in TG-DTA. Fly ash was kept reacting for long period and 42 - 54％ of fly ash was reacted after 555 days at 20℃. At the age of 365 days Ca（OH）₂ was enough remained for pozzolanic reaction of fly ash. And it is cleared that α-quartz was reacted at 20℃ and 40℃. The reaction of fly ash was more activated at curing temperature of 40℃ than 20℃. It is considered glass content and fineness of fly ash have much effect on pozzolanic activity. But it is guessed that the amount of modifier oxide of glass in fly ash can be evaluation figure when glass content and fineness of fly ash is similar.

RELATION BETWEEN MINERAL COMPOSITIONS OF FLY ASH AND ITS POZZOLANIC REACTION

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