Abstract
The effect of carbonate on the magnesium silicate hydrate (M-S-H) formation was studied at high Mg/Si molar ratio of 1.5. M-S-H pastes were synthesized from silica fume and MgO or MgO plus hydromagnesite in a Na 2 CO3 containing solution. X-ray diffraction data and thermogravimetric analysis indicated that brucite is destabilized and M-S-H phases formed much faster in the presence of carbonates. Additionally, in the system containing hydromagnesite, the hydromagnesite reacted to form M-S-H. In a third experiment, the carbonation of M-S-H with Mg/Si=1.5 in a suspension was investigated. While a reference suspension of M-S-H with Mg/Si=1.5 kept under inert atmosphere still contained brucite and a pH about 10.1, the forced carbonation of M-S-H decreased the pH to 7.3 and destabilized the brucite. No evidence of the formation of crystalline or amorphous hydrated magnesium (hydroxy)carbonate phases was observed.Abstract
The effect of carbonate on the magnesium silicate hydrate (M-S-H) formation was studied at high Mg/Si molar ratio of 1.5. M-S-H pastes were synthesized from silica fume and MgO or MgO plus hydromagnesite in a Na 2 CO3 containing solution. X-ray diffraction data and thermogravimetric analysis indicated that brucite is destabilized and M-S-H phases formed much faster in the presence of carbonates. Additionally, in the system containing hydromagnesite, the hydromagnesite reacted to form M-S-H. In a third experiment, the carbonation of M-S-H with Mg/Si=1.5 in a suspension was investigated. While a reference suspension of M-S-H with Mg/Si=1.5 kept under inert atmosphere still contained brucite and a pH about 10.1, the forced carbonation of M-S-H decreased the pH to 7.3 and destabilized the brucite. No evidence of the formation of crystalline or amorphous hydrated magnesium (hydroxy)carbonate phases was observed
