An economical and environmentally friendly strategy for the preparation of high-density fiberboards by replacing wood fiber with CaCO3

As an important component of interior materials, Fiberboard has advantages of being low-cost and renewable, but the practical use of firerboard was limited by depletion of forest resources and flammability. In this study, inspired by filler modification strategies employed in the papermaking industry, calcium carbonate (CaCO₃) was utilized as a functional filler to restructure the wood fiber matrix, yielding calcium carbonate-reinforced high-density fiberboard (CaCO₃-HDF) with multiscale interfaces. Experimental results demonstrate that at a density of 900 kg·m⁻³, the modulus of rupture (MOR) decreased from 60.51 MPa to 43.57 MPa with CaCO₃ substitution rates increasing from 0 % to 30 %. Notably, the internal bonding strength (IB) of the 30 % substitution sample reached 1.77 MPa, surpassing the control group's value of 1.65 MPa. Although the 24-hour thickness swelling (TS) increased proportionally with substitution rates, the material's thermal conduction efficiency was significantly enhanced, while formaldehyde emissions consistently met E0 standards. Combustion tests revealed substantially improved fire retardancy in 30 % CaCO₃-HDF (900 kg·m⁻³), with total mass loss (TML), total heat release (THR), total smoke production (TSP), and total CO production (TCOP) decreasing by approximately 26 %, 33 %, 48 %, and 63 %, respectively. This strategy establishes a novel pathway for producing cost-effective multifunctional fiberboards.