Impact of carbonation and fiber hornification on the performance of fiber-cements

Abstract The present study evaluates the effect and advantages of the combined use of two treatments on fiber-cement composites: 1) accelerated carbonation on the cement matrix and 2) hornification of commercially used unbleached pine pulp ( Pinus radiata D. Don). The premise of the study was to develop a composite with superior physical–mechanical performance, increased durability, all within a sustainability context. Chemical, physical, and morphological characterization of the pulps with and without treatment was conducted. For fiber-cement composites, instrumental techniques such as XRD, TGA, SEM, and physical–mechanical characterization (before/after accelerated aging) were applied. The heat treatment does not deteriorate the pulps and reduces their hygroscopicity. Accelerated carbonation enhanced matrix mechanical properties, increasing modulus of rupture by 51% and specific energy by 154%. The mass fraction of Ca(OH)₂ decreased from 11.1% to 0.3%, while the mass fraction of CaCO₃ increased from 37.0% to 60.2%. After 200 cycles of accelerated aging, composites with accelerated carbonation or treated pulps showed pulp preservation and matrix densification. Composites with combined treatments exhibited the best performance and durability before and after accelerated aging. The potential and feasibility of applying these combined treatments to fiber and matrix are established from technical, economic, and environmental perspectives.