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The effective utilization of fly ash (FA) as a raw material for ceramics production is performed on the FA-kaolin mixtures containing kaolins 10% by mass. The mixtures in comparison with FA and three raw kaolins were annealed to mullite ceramics at temperatures of 1000, 1100, 1200 and 1300 °C. The main aims were to contribute to the discussion on the effect of impurity of Na,K-feldspars in kaolins and Fe2O3 in FA on sintering procedure, porous ceramics properties and mullite structural properties. The phases were characterized using X-ray diffraction and thermogravimetry DTA/TGA methods. Mercury intrusion porosimetry was used for characterization of porosity of ceramic samples. Results evidenced the influence of feldspars in kaolins and Fe2O3 in FA on the sintering temperatures and properties of mullite ceramics. The fully FA-based ceramic sintered at 1100 °C exhibited post-sintering properties of bulk density 2.1 g/cm3; compressive strength 77.5 MPa; and porosity, 2% in comparison with the FA/kaolin-based ceramics properties of bulk density 2.2 g/cm3; compressive strength, 60–65 MPa; and porosity from 9.3 to 16.4% influenced by Na,K-feldspars. The best structural and mechanical characteristics were found for the FAK3 sample, supported by the high content of kaolinite and orthoclase in the kaolin K3 additive. The FAK3 annealed at 1100 °C exhibited good compressive strength of 87.6 MPa at a porosity of 10.6% and density of 2.24 g/cm3 and annealed at 1300 °C the compressive strength of 41.3 MPa at a porosity of 19.2% and density of 1.93 g/cm3.

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The aim of the present paper is to investigate the level of airborne wear particles released during the dyno-bench tests with the brake pads consisting of alkali-activated slag as an abrasive. Airborne wear particles are generated with a full-scale dyno-bench adapted for airborne wear particles emission studies. The tested disc brake is equipped with two semi-metallic brake pads and a grey cast iron brake disc. A reduced Los Angeles City Traffic (LACT) driving cycle, developed within the LOWBRASYS project (European Union’s Horizon 2020 research and innovation programme), is used to mimic city driving. The same friction pair is used six times with reduced LACT cycle. The weight loss and thickness of the pads and disc are registered after each test cycle ends. The amount of the airborne wear particles emissions released during each test cycle are characterized using a PM10 impactor and electric low-pressure impactor. The obtained data of wear particle emissions are correlated with the parameters of the brake stops. The maximum disc temperature was indicated as the parameter having the largest influence on the production of particle emissions together with the duration of the brake event