Rheological, mechanical, and microscopic properties of polypropylene fiber reinforced-geopolymer concrete for additive manufacturing

This study focuses on developing fiber-reinforced geopolymer concrete (GPC) for 3D printing, utilizing construction waste materials and polypropylene fibers. The GPC, reinforced with 0.8 %, 1.0 %, and 1.2 % polypropylene fibers by volume, underwent comprehensive testing, including rheological, mechanical, and microstructural analyses for lab-cast and 3D-printed samples. The results indicated that the 0.8 % polypropylene fibers enhanced flexural and tensile strengths by 8.2 % and 71.7 %, respectively, albeit decreasing compressive strength by 26.2 %. Higher polypropylene percentages led to adverse effects on material properties. Microscopic analysis revealed the formation of voids around fibers and features associated with incomplete hydration. The study emphasizes the need for optimizing water content and the use of longer polypropylene fibers. It also highlights the benefits of using GPC in the 3D printing of structural components.