Effects of polypropylene fibre on mechanical properties of fat clay stabilised with sludge ash of wood and paper mill

This study aims to evaluate the effect of sludge ash of wood and paper (SAWP) mill and polypropylene fibres on the mechanical properties of fat clay. For this purpose, a total of 122 unconfined compressive strength tests were conducted. X-ray diffraction analyses indicated that the main cementitious component induced by the addition of SAWP was calcite, which is a key factor for the strength enhancement in the stabilised specimens. The results showed that the addition of fibres to the SAWP-stabilised specimens increases their ductility, which can be investigated by energy absorption capacity, brittle index, and mode of failure. The results also illustrated that the fibres significantly improve the durability of the stabilised specimens. The use of fibres, while preventing the leachability of cementitious components and solid particles of the soil, prevents the development and spread of cracks in the specimen. Finally, the leachability of the heavy metals in the SAWP-stabilised specimens was lower than the regulated values. Hence, this study corroborates the effectiveness of fibre-reinforced SAWP-stabilised specimen as a durable and sustainable composite material.