The paper is focused on the observation of the influence of alternative filler on rubber compounds properties. The sludge from the
weighed ingredients of glass batch in the glass production was used in the position of the alternative filler. This alternative filler
was modified by using of three silanes: 3-aminopropyltriethoxysilane, bis(triethoxysilyl)propyl-tetrasulfide and 3-(triethoxysilyl)propylmethacrylate
and was applied into rubber compounds. The composition differences of rubber compounds were based on the
different amount and type of filler. The samples were characterised by determination of the curing characteristics and physicalmechanical
properties. From the measured results, it can be concluded that the modification of alternative filler showed
a favourable effect on the properties of rubber compounds in comparison with unmodified alternative filler.