TY - JOUR
T1 - Structural evolution of synthetic alkali-activated CaO-MgO-Na2O-Al2O3-SiO2 materials is influenced by Mg content
AU - Walkley, B.
AU - San Nicolas, R.
AU - Sani, M.-A.
AU - Bernal, S.A.
AU - van Deventer, J.S.J.
AU - Provis, J.L.
PY - 2017/9/30
Y1 - 2017/9/30
N2 - Stoichiometrically controlled alkali-activated materials within the system CaO-MgO-Na2O-Al2O3-SiO2 are produced by alkali-activation of high-purity synthetic powders chemically comparable to the glass in ground granulated blast furnace slag, but without additional minor constituents. Mg content controls the formation of hydrotalcite-group and AFm-type phases, which in turn strongly affects C-(N)-A-S-H gel chemistry and nanostructure. Bulk Mg content and the Mg/Al ratio of hydrotalcite-group phases are strongly correlated. With sufficient Ca, increased bulk Mg promotes formation of low-Al C-(A)-S-H and portlandite, due to formation of hydrotalcite-group phases and a reduction in available Al. Hydrotalcite-group phase formation is linked to increased C-(N)-A-S-H gel polymerisation, decreased gel Al uptake and increased formation of the ‘third aluminate hydrate’. These findings highlight the importance of considering available chemical constituents rather than simply bulk composition, so that the desired binder structure for a particular application can be achieved.
AB - Stoichiometrically controlled alkali-activated materials within the system CaO-MgO-Na2O-Al2O3-SiO2 are produced by alkali-activation of high-purity synthetic powders chemically comparable to the glass in ground granulated blast furnace slag, but without additional minor constituents. Mg content controls the formation of hydrotalcite-group and AFm-type phases, which in turn strongly affects C-(N)-A-S-H gel chemistry and nanostructure. Bulk Mg content and the Mg/Al ratio of hydrotalcite-group phases are strongly correlated. With sufficient Ca, increased bulk Mg promotes formation of low-Al C-(A)-S-H and portlandite, due to formation of hydrotalcite-group phases and a reduction in available Al. Hydrotalcite-group phase formation is linked to increased C-(N)-A-S-H gel polymerisation, decreased gel Al uptake and increased formation of the ‘third aluminate hydrate’. These findings highlight the importance of considering available chemical constituents rather than simply bulk composition, so that the desired binder structure for a particular application can be achieved.
UR - http://www.scopus.com/inward/record.url?eid=2-s2.0-85019387408&partnerID=MN8TOARS
U2 - 10.1016/j.cemconres.2017.05.006
DO - 10.1016/j.cemconres.2017.05.006
M3 - Article
SN - 0008-8846
VL - 99
SP - 155
EP - 171
JO - Cement and Concrete Research
JF - Cement and Concrete Research
ER -