Characterisation and hydration process of synthetic Sr-bearing ye'elimite

Abstract

2+ions in C 4 A 3 $, Sr-bearing ye'elimite can be synthesised. In this paper, a kind of Sr-bearing ye'elimite was synthesised with the formula 3CaO·SrO·3Al 2 O 3 ·SO 3 (abbreviated as C 3 ŠA 3 $); the characterisation and hydration process of C 3 ŠA 3 $ are reported here. Comparing to C 4 A 3 $, mineralogical analysis of C 3 ŠA 3 $ was conducted, and Rietveld quantitative phase analysis was employed to quantify the hydration products of C 3 ŠA 3 $ and correlate to calorimetric data. Results show that C 3 ŠA 3 $ accounts for over 93% in the clinker, and the ACn contents are insignificant in terms of amounts. Without gypsum, the hydration process of C 3 ŠA 3 $ is more retarded and prolonged than C 4 A 3 $ at an early stage. In the hydration products of C 3 ŠA 3 $ at 28 d, AFt accounts for 28·2% and AFm occupies 13·4%; CAH 10 is quantified to be 5·5%. Compared to C 4 A 3 $, C 3 ŠA 3 $ tends to yield more AFt. As regards C 3 ŠA 3 $ hydrating with a certain amount of gypsum, the hydration rate of C 3 ŠA 3 $ is accelerated to approach C 4 A 3 $ blended with gypsum. In the paste of C 3 ŠA 3 $ blended with gypsum at 28 d, AFt occupies the majority of crystalline phases to take up 42·1%; minor phases AFm and strontium sulfate account for 3·1% and 7·4%, respectively.Rietveld refined weight fraction of zinc oxide R wp weighted-profile R value (%) r radius of ion W st weight fraction of added zinc oxide

Microstructural comparison of the AH3 phase in the hydration of three structural modifications of ye'elimite

“…The cubic system of Sr‐bearing ye'elimite increased at the expense of the orthorhombic system with increasing substitution of Sr ( x = 0.25, 0.50, 0.75, 1.00 in (4‐ x )CaO·xSrO·3Al 2 O 3 ·SO 3 ), but Ba‐bearing ye'elimite maintained a cubic system in the presence of Ba regardless of its amount ( x = 0.25, 0.50, 0.75, 1.00 in (4‐ x )CaO·xBaO·3Al 2 O 3 ·SO 3 ) . Additionally, the hydration process of 3CaO·SrO·3Al 2 O 3 ·SO 3 (C 3 ŠA 3 ) reacted slower than that of st‐ye'elimite at an early age …”