Abstract: To reduce the cost and environmental burden of supersulfated cement caused by using Portland cement as an
alkaline activator,this study completely replaces Portland cement with strongly alkaline solid waste calcium carbide residue
(main component Ca(OH)2) and its modified product (calcined at 520 ℃) to prepare super sulfate cement. The effects of
Portland cement,raw calcium carbide residue,and modified calcium carbide residue as activators on cement fluidity,setting
time,compressive strength,and hydration products were systematically studied. The results show that raw calcium carbide residue,
due to its larger particle size,increases mortar fluidity by 6. 42% but significantly delays setting due to low reactivity.
Modified calcium carbide residue,with increased specific surface area and formation of highly active CaO,effectively shortens
setting time. Although the 7-day compressive strength of the modified calcium carbide residue system (11. 73 MPa) is lower
than that of Portland cement (15. 96 MPa),its 28-day compressive strength reaches 42. 81 MPa,equivalent to Portland cement
(43. 58 MPa) and meeting the national standard requirement for 42. 5-grade cement. XRD and FTIR analyses indicate that hydration
products in all systems are primarily ettringite and C-S-H gel,with calcium carbide residue promoting ettringite generation
at later ages. This study proves that modified calcium carbide residue can serve as an effective alkaline activator to achieve
equivalent long-term mechanical performance with low-carbon preparation of super sulfate cement.

Key words: calcium carbide slag,supersulfated cement,calcination modification,mechanical properties,hydration characteristics