Waste sandstone from the Binh Phuoc quarry has been researched and used as an active mineral additive when mixed with Portland cement. Aspects of the influence of sandstone content (up to 20 wt.%) on the mechanical strength of sandstone blended cement were studied. The results of systematic research according to current standards show that this type of sandstone has the properties of an active mineral additive and the sample mixed with 15% sandstone meets the mechanical strength standards of an active mineral additive after curing days. The results of SEM and XRD microstructure studies have shown that the minerals formed in the sandstone blended cement are equivalent to ordinary Portland cement. This ensures strength development over a longer use of the sandstone blended cement similar to ordinary Portland cement.