The paper presents the results of research on the utilization of textile denim sludge waste, which was used to obtain concrete and mortar. For this purpose, cement and sand were replaced with the powdered sludge in the amount of 5 and 10 wt. The sludge was initially analyzed by FTIR and XRD to identify functional groups and chemical composition, respectively. Replacing sand with sludge resulted in a significant reduction in the concrete compressive and flexural strength (> 50%). Significantly
better results were obtained by replacing cement with 5 wt% of sludge. In this case, the concrete compressive
strength decreased by only 14%, and the flexural strength by 15%.