Synthesis and hydration of alite-calcium sulfoaluminate cement

Abstract

An alite-calcium sulfoaluminate (ACSA) clinker containing approximately 50% alite and 10% ye'elimite was synthesised at 1300°C using a laboratory furnace and 1% calcium fluoride (CaF2) as a mineraliser, ground and blended with 5% anhydrite. The hydration mechanism of the resulting ACSA cement was investigated experimentally using quantitative X-ray diffraction and thermogravimetry, as well as by thermodynamic modelling. During the first hours, mainly alite reacts. Ye'elimite starts to dissolve significantly after 2 d, as it is predominately present as inclusions within the alite matrix and thus reacts only after sufficient alite has dissolved to expose the ye'elimite domains within the clinker particles. The main hydration products are calcium–silicate–hydrates (C–S–H), ettringite, monosulfate and portlandite. Mortars prepared using the ACSA cement rapidly develop compressive and flexural strength at early ages corresponding to the fast hydration reactions. It was estimated that the manufacture of this ACSA clinker releases about 11–12% less carbon dioxide than the production of Portland cement clinker.

Nanostructural characterization of Al(OH)3 formed during the hydration of calcium sulfoaluminate cement

“…Calcium sulfoaluminate (CSA) cements are seeing an increase in attention worldwide as sustainable construction materials due to their potential environmental benefits and their performance superiority for special applications . CSA cements require smaller amounts of limestone in the raw material to be decarbonized and require a lower sintering temperature (around 1250°C) when compared to portland cement . When compared with portland cement clinkers, CSA cement clinkers tend to be more friable due to their high porosity and hence require less electricity to grind .…”

“…[1][2][3][4] CSA cements require smaller amounts of limestone in the raw material to be decarbonized and require a lower sintering temperature (around 1250°C) when compared to portland cement. [5][6][7][8] When compared with portland cement clinkers, CSA cement clinkers tend to be more friable due to their high porosity and hence require less electricity to grind. 9,10 CSA cements have a number of positive attributes such as rapid setting and rapid hardening, shrinkage compensating and self-leveling depending on the amount of calcium sulfate added and the type of calcium sulfate (anhydrite or gypsum).…”

Effect of Nano-SiO2 on the Early Hydration of Alite-Sulphoaluminate Cement

“…AC$A cement, also called high calcium sulphoaluminate cement, performs well as an energy-saving cement [ 36 ]. AC$A cement clinker containing sulphoaluminate (C 4 A 3 $) can be synthesized through annealing [ 37 , 38 ], or by mineralizers such as CaF 2 [ 39 , 40 ], CuO [ 41 ] and ZnO [ 42 ].…”

Effect of Elevated Temperature on Mechanical Properties of Waste Polymers Polyethylene Terephthalate and Low Density Polyethylene Filled Normal Concrete Blocks

“…In the NC spalling at high temperatures caused internal pressure to build up due to the evaporation of both free and bound water which caused propagation of micro cracks leading to spalling of the NC surface. However, in the plast-cretes; the melted plastics absorbed within the matrix of the plast-crete created a path way where gases (water vapour) that were generated due to heating can easily be released; this reduced the effect of spalling in the plast-cretes [23,28,29].…”