Abstract
The effect of fly ash on controlling alkali-silica reaction(ASR) in simulated alkali solution was studied. The expansion of mortar bars and the content of Ca(OH)2 in cement paste cured at 80 °C for 91 d were measured. Transmission electron microscopy(TEM) and high- resolution transmission electron microscopy(HRTEM) were employed to study the microstructure of C-S-H. TEM / energy dispersive spectroscopy(EDS) was then used to determine the composition of C-S-H. The pore structure of the paste was analyzed by mercury intrusion porosimetry(MIP). The results show that the contents of fly ash of 30% and 45% can well inhibit ASR. And the content of Ca(OH)2 decreases with the increase of fly ash. That fly ash reacted with Ca(OH)2 to produce C-S-H with a low Ca/Si molar ratio could bind more Na+ and K+ ions, and produce a reduction in the amount of soluble alkali available for ASR. At the same time, the C-S-H produced by pozzolanic reaction converted large pores to smaller ones(gel pores smaller than 10 nm) to densify the pore structure. Perhaps that could inhibit alkali transport to aggregate for ASR.
| Original language | English |
|---|---|
| Pages (from-to) | 168-171 |
| Number of pages | 4 |
| Journal | Journal Wuhan University of Technology, Materials Science Edition |
| Volume | 21 |
| Issue number | 3 |
| DOIs | |
| State | Published - Sep 2006 |
Keywords
- Alkali
- Alkali-silica reaction
- C-S-H
- Cal Si molar ratio