Mechanical properties, fire resistance, and durability of bricks produced with wheat and corn straw fiber treated with hot water

• Reusing wastewater from straw fiber treatment in the straw fiber treatment and brick manufacturing. • Determining the fire resistance and durability of the straw fiber bricks containing straw fibers treated with hot water at 50°C. • Analyzing the impact of the straw fiber treatment method on the performance of straw fiber bricks. • The optimal mixing of treated wheat and corn straw fibers and ashes with cement-based materials was developed to produce straw fiber bricks as an alternative to conventional bricks. • The thermo-mechanical behavior of straw fiber bricks under prolonged fire exposure was established using numerical simulation models. The use of bricks made with natural straw fibers is increasingly being explored for sustainable building; however, their mechanical properties and durability, as well as the environmental impact of treating straw fibers, remain challenging. This paper presents an investigation into the effects of treatment methods, microstructure, flexural and compressive strength, density, water absorption, and thermal conductivity of manufactured wheat and corn straw fiber cementitious composite (WCSFCC) samples. Moreover, the fire resistance of wheat and corn straw fiber bricks (WCSFB) was investigated and supported by a developed numerical simulation. Findings demonstrated the formation of strong interphase bonding between the hot-water-treated straw fibers and the cement matrix. Moreover, the FTIR spectra displayed a strong O-H bond, indicating the hydrophilicity of WCSFB. Adopting straw fibers treated with 50°C hot water significantly improved the performance of WCSFCC, yielding increases in compressive strength and flexural strength of 54.3% and 36.8%, respectively, while simultaneously reducing toughness and thermal conductivity by 12% and 12.36% compared with WCSFCC treated with NaOH. Fire resistance testing indicated that wheat and corn straw fiber bricks made with hot-water-treated straw fiber (WCSFB–HW) have a fire resistance rating of 240 minutes, making them non-combustible. The numerical simulation model closely matches experimental results and explains the deformation mechanisms.