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The influence of technogenic waste (burned and unburned mullite wool) on the properties of cement concrete as well as the influence of unburned mullite wool on the properties of ceramics are analysed in the paper. For the purpose of research, the part of sand in a cement concrete (2%, 4%, 6%, 8%, 10%) was replaced by a mullite wool waste. When 10% of the burned mullite wool waste was used the compressive strength of concrete increased by 7.7% after 7 days, and by 3.2% after 28 days. When 8% of the unburned mullite wool waste was used the compressive strength of concrete decreased by 3.4% after 7 days, and by 12.2% after 28 days. The ceramic samples were made from 4 different formation mixtures, in which the amount of unburned mullite wool waste was 0%, 5%, 10% and 15% (the amounts of quartz sand were replaced with waste). The samples were burned at the temperatures of 1050 °C and 1080 °C, keeping them at these temperatures for 4 h. The experimental results showed that the application of mullite wool waste in the manufacture of ceramic products is beneficial because of its positive impact on ceramic properties and the possibility to avoid overloading landfill sites. At the optimum burning temperature of 1080 °C, the significantly higher frost resistance, compressive strength and lower water absorption of ceramics is obtained., The authors gratefully acknowledge the help of the VGTU Civil Engineering Centre in providing the laboratory equipment, which was used in the present investigation.

This paper is aimed to show the impact of bitumen roofing production waste (BTw) on the properties of cement mortars in terms of mineral composition, microstructure, setting rate, physical and mechanical properties and durability (water absorption, freeze-thaw resistance). To this aim, mortar specimens were manufactured by replacing 0%, 2%, 4%, and 6% of natural sand by weight with BTw. The main results show that BTw slightly accelerates cement hydration and 4% is the best content of BTw to be valorised in mortars. In this case, compressive strength, density and ultrasound pulse velocity are comparable to the control mortar (0% BTw content) but capillary water absorption decreases and flexural strength increases. Moreover, at this dosage, the forecasted freeze-thaw resistance of mortars increases considerably (~30%).