Title:
Mitigation of ASR Expansion by Biomass/Coal Fly Ash and the Underlying Mechanism by Pore Solution Chemistry
Author(s):
S. Wang, S. Bragonje, J. Tullis, R. Dalton,
and L. Baxter
Publication:
Symposium Paper
Volume:
242
Issue:
Appears on pages(s):
267-278
Keywords:
alkali silica reaction; biomass fly ash; expansion; pore solution
DOI:
10.14359/18720
Date:
4/1/2007
Abstract:
This investigation experimentally documents mitigation of alkali-silica-reaction (ASR) expansion through partial replacement of cement with coal-biomass cofired fly ash. ASTM C 227 and 441 guide the experimental techniques. Biomass and Class F fly ash reduce ASR expansion within 0.1% at the 6 month with 35% replacement ratio, although biomass fly ash has much higher available Na2Oequiv (by ASTM C 33). Further analysis of pore solution by high pressure extrusion illustrates that biomass fly ash mixes have similar alkali metal concentrations to Class C mixes, but biomass fly ash is at least equal or much better than Class C in mitigating ASR expansion; this implied that biomass fly ash may absorb alkalis from the pore solution and may form non-expansive products instead of the expansive alkali silica gel.