Sol-gel treated pulp and accelerated carbonation curing: A novel approach for high-performance bamboo fibre cement composites

This is a pioneering work on stabilising the dimensional variations of fibre cement composites reinforced with natural plant fibres. Organosolv bamboo (Dendrocalamus asper) pulp and commercial pine (Pinus taeda) pulp were treated with sol-gel (based on tetraethyl orthosilicate and hexadecyltrimethoxysilane silanes) and used as reinforcement in an inorganic fibre cement matrices. The fibre cement composites containing 77.2 % Portland cement and 12.8 % limestone were reinforced with 10 % (w/w) of the sol-gel treated or non-treated pulps, subjected to accelerated carbonation, and thermally cured at early ages. The physical-mechanical performance and dimensional stability of these fibre cement composites reinforced with the treated and non-treated pulps were evaluated and compared with their non-carbonated fibre cement counterparts. The physical-mechanical results of non-carbonated composites showed no statistically significant difference between the formulations reinforced with bamboo and commercial pine pulps. Although the sol-gel treatment of the pulp decreased the composite's strength by up to 32 % (to 7.44 MPa), the dimensional stability was improved by up to 50 %, emphasising the better stability of fibre cement reinforced with sol-gel-treated bamboo pulp of 0.9 mm/m shrinkage. The carbonated and thermally cured fibre cement reinforced with sol-gel-treated bamboo pulp reached a modulus of rupture of 13.80 MPa. In comparison, the specimens reinforced with sol-gel-treated pine pulp presented 9.54 MPa. The sol-gel treatment applied to the pulp and the accelerated carbonation efficiently improved the dimensional stability of the fibre cement composites with an acceptable decrease in mechanical performance. Most importantly, the fibre cement cured with accelerated carbonation was capable of capturing CO₂ at its early age, mitigating the carbon footprint in the production chain.