Influence of water-soluble leachates from natural fibers on the hydration and microstructure of cement paste studied by nuclear magnetic resonance

This study aims to evaluate the influence of natural fiber leachates on cement pastes for advanced bio-composite production. Cement samples are made by mixing cement with leachates from oil palm and coir fibers at three concentrations. Through Nuclear Magnetic Resonance T₁-T₂ relaxations, fresh cement samples are evaluated for hydration reaction and microstructure. Results show that oil palm fiber leachates prolong plateaus in T₁ and T₂, suggesting a retarding effect on cement hydration. Subsequently, increased T₁ values and an extra T₂ component are observed which suggest coarser pores. Additionally, the leachates increase water fractions, reflecting reduced cement hydration degree. With increasing leachate concentration, the retarding effect and extra larger pores become apparent. Conversely, coir fiber leachates exhibit negligible influence. This difference is attributed to the less saccharides. These saccharides function through simultaneous adsorption, nucleation, complexation and precipitation. In conclusion, coir fibers demonstrate better compatibility with cement than oil palm concerning leachates.