To reduce the carbon footprint of common construction materials like mortar and concrete, previous research has focused on the combination of natural sand and gravel with cement-based materials. However, the application of porous particles such as waste red bricks, a common byproduct of the building construction, and artificial lightweight aggregates sintered from industrial sludge has been less studied. This study therefore used waste red brick sand and artificial lightweight sand instead of natural river sand to prepare mortar cube specimens for study. The study compared the effects of CO2 curing on the engineering properties of the two mortars and their CO2 sequestration effectiveness. The test results showed that red brick mortar had slightly better workability than lightweight sand mortar. However, in terms of compressive strength, ultrasonic pulse velocity, and water absorption, the lightweight sand mortar performed better, with higher strength and faster velocity than red brick mortar, and lower water absorption. This indicates that lightweight sand mortar is more effective in CO2 sequestration than red brick mortar.