Degree of Fly Ash Reaction in Internally Alkali-Activated Cement Paste

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Title: Degree of Fly Ash Reaction in Internally Alkali-Activated Cement Paste

Author(s): Phuong Trinh Bui, Yuko Ogawa, Kenichiro Nakarai and Kenji Kawai

Publication: Special Publication

Volume: 320

Issue:

Appears on pages(s): 31.1-31.14

Keywords: cement paste, fly ash, internal activation, mercury intrusion porosimetry, NaOH solution, porosity, pozzolanic reaction, selective dissolution method

Date: 8/1/2017

Abstract:
The present study aimed at investigating the degree of fly ash reaction and porosity up to 12 months of aging for cement paste specimens internally activated by natural injection of NaOH solution and those internally cured by injection of deionized water 1 month after casting, to assess the positive effect of internal alkali activation. In addition, reference specimens were fabricated with no solution injection. Two replacements of cement by fly ash were 0% (Fa0) and 40% (Fa40) by mass. Degree of fly ash reaction in Fa40 internally activated by NaOH solution was higher than that in Fa40 internally cured by water or no solution. Injection of solution decreased the volume proportion of pores ranging 0.02–0.33 μm (7.87 × 10-7–1.29 × 10-6 in.) to total pores and increased that of pores ranging 0.003–0.02 μm (1.18 × 10-7–7.87 × 10-7 in.) in Fa40, more than that of wno solution up to 12 months. Meanwhile, those volume proportions in Fa0 were only affected significantly by injection of solution at 12 months. Consequently, it can be concluded that pozzolanic reaction of fly ash was accelerated in cement paste internally activated by NaOH solution.