Thermogravimetry analysis, compressive strength and thermal conductivity tests of non-autoclaved aerated Portland cement-fly ash-silica fume concrete

Abstract

© 2015 Akadémiai Kiadó, Budapest, Hungary. This paper reports the investigated thermogravimetry analysis, compressive strength and thermal conductivity tests of non-autoclaved aerated Portland cement-fly ash-silica fume concrete. The mixes were cured in water and air for 3, 7 and 28 days. Thermogravimetry results showed that calcium silicate hydrate (C-S-H), ettringite, gehlenite (C<inf>2</inf>ASH<inf>8</inf>), calcium hydroxide [Ca(OH)<inf>2</inf>] and calcium carbonate (CaCO<inf>3</inf>) phases were detected in all mixes. The compressive strength and thermal conductivity of aerated Portland cement-fly ash-silica fume concrete increased when compared with aerated Portland cement-fly ash concrete after 28 days. The compressive strength and thermal conductivity of aerated concrete cured in water had higher values than air-cured specimens. X-ray diffraction and thermogravimetry showed that Ca(OH)<inf>2</inf> decreased with increased silica fume content. This is due to the increased pozzolanic reaction when compared with the Portland cement-fly ash mixes, which corresponds to an increase in compressive strength and thermal conductivity.