In recent years, the deep mixing technique that utilizes cement-based grout mixtures has become a popular approach, particularly for the enhancement of soft soils. Despite the advantages of deep mixing technique in numerous construction applications, the effort given for this technique still needs to be extended using new material as additive. Thus, this study investigates the use of cement-based grout combined with glass powder to enhance the clay soil via deep mixing technique. An experimental program has been conducted including grout mixtures at different replacements of glass powder (0%, 3%, 6% and 9% by dry weight of binder) mixed with clay having different water contents (36%, 31% and 21%). The Vicat, unconfined compressive strength (UCS) and ultrasonic pulse velocity (UPV) tests have been carried for analysing performances of mixtures. The results indicate that the setting times of the mixture pastes increase, while the bulk densities of the soilcrete samples do not significantly change with the replacement of glass powder. Moreover, due to the use of glass powder, both the UCS and UPV increase alongside decreasing water content as well as increasing curing time. Test results imply that, owing to the replacement of glass powder, all UCS values of the soilcrete samples are applicable for the purpose of deep mixing. However, the replacement of glass powder by 3% produces a more favorable UCS response. Strong correlations exist for the UCS versus elastic modulus (R ⩾ 0.84) as well as for the UCS versus UPV (R ⩾ 0.82), which practically could be useful for the strength predictions of soil-cement columns. Consequently, the use of cement-based grout with the glass powder replacement could provide a new insight into the deep mixing technique for the treatment of clay. Moreover, the employment of glass powder as a waste material could also benefit the environment and construction costs. [ABSTRACT FROM AUTHOR]