Enhanced pozzolanic activity of microcrystalline cellulose via silane modification for cementitious composites

Abstract

Abstract This study evaluated the effect of surface functionalization of microcrystalline cellulose (MCC) with tetraethyl orthosilicate (TEOS) on its physicochemical properties and the performance of cement-based microconcretes incorporating the modified material. Eleven MCC samples were functionalized by varying the pH, TEOS ratio, and temperature. The MCC samples were characterized using Fourier Transform Infrared Spectroscopy (FTIR), X-ray Diffraction (XRD), Thermogravimetric Analysis (TGA), Scanning Electron Microscopy (SEM), and the modified Chapelle test. The results confirmed the incorporation of TEOS on the MCC surface, evidenced by a reduction in hydroxy groups, formation of siloxane bonds, and improved thermal stability. Samples 3, 7, 9, and 10 showed improved microstructural characteristics according to XRD, TGA, and FTIR analyses, confirming effective surface functionalization. Among them, Sample 3 was selected for microconcrete production due to its higher reactivity and process feasibility. The modified Chapelle test indicated high pozzolanic activity (a measure of the capacity of a siliceous or aluminous material to consume or fix calcium hydroxide), with a maximum calcium hydroxide consumption of 1066.06 mg g⁻ 1 . The addition of treated MCC to microconcretes resulted in early-age strength gains, attributed to its reactivity and nucleation effect. It is concluded that TEOS treatment is a promising strategy to enhance the performance of cementitious materials. This study shows that surface-functionalised MCC can act as a reactive and sustainable additive that enhances the microstructure and mechanical performance of cementitious composites.