Assessment of the potential use of eucalyptus pulp, mineral additions and carbonation in extruded fiber cement

This study investigates an innovative approach to the production of low-carbon extruded fiber cement, utilizing the combination of eucalyptus pulp, copper tailings and accelerated carbonation curing. The ideal proportion of the identified mixture was 10% eucalyptus pulp combined with 27% Sossego copper tailings and 63% ordinary Portland cement. This formulation achieved a flexural strength of 12.74 MPa, a value significantly higher than the 8.87 MPa of the reference and above Brazilian requirements for non-structural elements. In physical terms, the inclusion of 10% fibers increased the initial apparent porosity by 103%. The fibers created pathways that made the carbonation efficiency 33% higher compared to matrices without fibers. The maximum degree of carbonation achieved was 54.3% in the mixtures with 63% copper tailings. Curing by carbonation promoted a pore-blocking effect, reducing the apparent porosity by an average of 25% due to the formation of calcite, which occupies a larger molar volume than portlandite. Carbonation protects cellulose fibers by reducing the surface pH by 21%, mitigating alkaline degradation. X-ray diffraction and microstructural analysis confirmed the formation of calcite phase, contributing to the refinement of pores in the matrix. These discoveries contribute to the environment through the development of eco-friendly products.