In this study, calcium sulfoaluminate cement (CSAC) was used as a more sustainable material to stabilize high plastic clayey soil compared to ordinary Portland cement (OPC). Both CSAC and OPC were used and studied as soil stabilizers. The percentages of both cements used were 2.5 %, 5.0 %, and 7.5 % by dry weight of soil and cured for 0, 7, 14, and 28 days in a water bath. The clayey soil was characterized by using the Atterberg limit, specific gravity, and miniature Proctor test. Samples for the unconfined compressive strength (UCS) and ultrasonic pulse velocity (UPV) tests were prepared at optimum moisture content and maximum dry density. The stabilized clay samples were tested for UCS and UPV tests as per American Society of Testing and Materials guidelines. Results showed that both types of cement improved the strength of the clayey soil with curing periods. The UCS test showed that samples prepared with CSAC were stronger without curing, but OPC-treated samples showed higher strength after a curing period. The UCS value reached a maximum of 1,758.16 kN/m² for 7.5 % CSAC-treated samples at 28 days of curing, whereas the UCS value reached up to 3,261.22 kN/m² for OPC-treated samples. The UPV test also showed that the addition of both types of cement to clayey soil samples increased its strength. The UPV value for untreated soil was 990.5 m/s, whereas CSAC-treated samples showed an increase between 1,275.13 and 1,647.8 m/s. The OPC-treated samples had an increase between 1,355.25 and 2,043.63 m/s. All OPC-treated samples had higher UPV values than CSAC-treated samples.