Compression strength properties of gypsum matrix composites with recovered fibrous scrap materials from post-consumer tyres

Gypsum-based experimental cylindrical samples were prepared using three fractions of recycling tyre 'fluff' material ('as received', fractions >4 mm and <4 mm) in three proportions (10%, 20%, 30%) by weight. The density values of the samples were found to decrease with increasing the proportion of 'fluff' material incorporated in gypsum. Compressive strength and density of cylindrical samples were positively correlated for all combinations, and their relationships were found statistically significant. Compressive strength values ranged between 1.00-7.64 N/mm2 for the 'fluff' fraction <4 mm, where they were the highest, 0.37-1.59 N/mm2 for the 'fluff' fraction >4 mm, where they were the lowest, and between 0.39-4.22 N/mm2 for the 'fluff' fraction 'as received' during recycling, where they were intermediate. Calculations of the required compressive strength in the case of using 'gypsum-fluff' building bricks in interior walls showed that all 'gypsum-fluff' combinations exhibited the adequate strength to perform successfully.