The mechanical and microstructural investigations of concrete incorporating waste textile and cardboard fibers following thermal and freeze–thaw cycles

Abstract Recent research suggests that incorporating waste fiber materials into concrete can enhance sustainable waste management practices and reduce the need for extracting natural resources. Textile and cardboard waste, which are abundantly available worldwide, offer significant opportunities to be repurposed in building materials, simultaneously minimizing landfill waste. This study explores the durability of concrete composites containing textile and cardboard fibers, with a focus on using silica fume as a modification technique for the kraft fiber walls (SFKFs) found in cardboard waste. SFKFs replaced 5% of the cement by volume (SFKF5), while 2.5% polyester textile fibers (T2.5) were added as a reinforcement agent. Microstructural analysis showed variations in how fibers were integrated into the concrete matrix. The rougher surfaces of SFKFs improved fiber anchorage, while the smooth texture of textile fibers promoted uniform dispersion. Mechanical testing, including compressive, tensile, and durability tests, was conducted on all composite specimens by subjecting them to thermal and freeze–thaw cycles. Observations of weight loss and strength characteristics supported the mechanical results. The SFKF5 composite showed a 23.9% increase in compressive strength after 100 thermal cycles. Initially, the combination of SFKF5 and T2.5 (KFT) demonstrated the highest tensile strength at 28 days. However, SFKF5 outperformed T2.5 in tensile strength after 100 thermal cycles. The T2.5 specimen exhibited the highest compressive strength of 45 MPa and achieved the highest tensile strength of 4.3 MPa following 100 freeze–thaw cycles. These findings confirm the durability of waste fiber reinforced concrete under various environmental conditions, highlighting its potential as a sustainable construction material.