Comparative Study of Cement Composites Reinforced with Cellulose and Lignocellulose Fibers

The urgent need to decarbonize the construction sector has prompted research into sustainable alternatives to conventional concrete. This study compares two industrially produced pulps with contrasting lignin contents: a bleached kraft cellulose pulp with near-zero lignin used in paper production and a thermo-mechanical lignocellulose pulp with high lignin content used in MDF production. Fiber-reinforced composites were produced by partially replacing mineral aggregates with fibers at dosages from 0.1% to 3% by mass and air-curing to simulate practical curing conditions. The specimens were evaluated for density, water absorption, and compressive strength, with compressive strength measured at 7, 28, and 60 days. Results showed a reduction in density for both fiber types, along with increased water absorption and decreased compressive strength at higher fiber contents. Cellulose composites achieved a more favorable mechanical performance than lignocellulose composites but showed markedly higher water absorption, raising concerns about long-term durability. By testing two pulps that differ primarily in lignin content across multiple replacement ratios, the study provides a systematic comparison of their effects on composite properties. The comparison explicitly contrasts the lignin contents of the two industrial pulps—bleached kraft (~0.1%) versus thermo-mechanical (27.4%)—to isolate lignin-driven effects on hydration and property development. A practical air-curing protocol was adopted, leveraging fiber-bound/process water, thereby reflecting use cases where external water curing is constrained.