Preliminary survey of the stability of silica-rich cementitious mortars 82-22 and 84-12 with tuff
Two cementitious formulations were prepared that contained mixtures of silica-adjusted cementitious binder and tuff of the Topopah Spring Member. Both formulations were developed to possess a bulk chemical composition that approached the bulk silica-to-alumina ratio of the tuff of the Topopah Spring Member. The two formulations represent examples of an expansive (82-22) and a nonexpansive (84-12) cementitious sealing material. The expansive grout relies on the formation of ettringite to generate the expansive forces. Phase characterization of the reaction products for the expansive grout revealed that the expansive agent, ettringite, was not stable above about 100{degree}C. Tobermorite was observed at all temperatures, even at 300{degree}C, well above its expected stability limit. The incorporation of Al into the tobermorite structure is postulated as contributing to the enhanced thermal stability. In the longer experiments, at 200 and 300{degree}C, the Al-tobermorite partially reacted with excess SiO{sub 2} to form truscottite, another calcium silicate hydrate. This observation is consistent with the solution analyses that suggest that the liquid phase in contact with the seal material is very nearly at equilibrium with respect to quartz at 150{degree}C and slightly undersaturated with respect to quartz at 200{degree}C. 12 refs., 11 figs., 12 tabs.
- Research Organization:
- Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
- DOE Contract Number:
- W-7405-ENG-36
- OSTI ID:
- 60691
- Report Number(s):
- LA-11222-MS; ON: DE89009692
- Resource Relation:
- Other Information: PBD: Mar 1989
- Country of Publication:
- United States
- Language:
- English
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