Enhancing cement-wood compatibility through hot-water extractives removal from logging waste of two Amazonian timber species

Abstract The compatibility between wood and cement is a challenge in producing composites from lignocellulosic residues. This study investigated the influence of extractives from two Amazonian wood species, Dinizia excelsa and Dipteryx odorata , on the hydration of high-early-strength Portland cement and evaluated the efficacy of extraction methods in improving compatibility. Wood sawdust was subjected to four treatments: cold water (CW), hot water in a bath (HW-bath), hot water in a Soxhlet apparatus (HW-Soxhlet), and total extractives (TE) removal with toluene-ethanol. The compatibility was assessed through X-ray diffraction (XRD), electrical conductivity, semi-adiabatic calorimetry, and compatibility indices (CT, CA, CX, CA 24 h , Cs). The results showed that polar, water-soluble extractives were the cause of hydration inhibition. The HW-Soxhlet extraction was the most effective water-based method, removing a percentage of extractives equivalent to 92 and 99% of the TE content for D. odorata and D. excelsa , respectively. D. excelsa exhibited moderate innate incompatibility (Cs ≈ 34%), which was significantly improved by extractive removal. In contrast, D. odorata was severely inhibitory in its raw state (Cs ≈ 8%) and required intensive treatments to achieve acceptable compatibility (Cs ≈ 61% for both HW-Soxhlet and TE). The HW-Soxhlet treatment promoted hydration kinetics and the formation of key hydrated phases (ettringite, portlandite) similar to neat cement. Among the compatibility indices, Cs and CX provided the most reliable assessment. It is concluded that the compatibility of these Amazonian woods with cement can be managed by pre-treatment, with HW-Soxhlet extraction being recommended for the production of cement-wood composites.