Effectiveness of cellulose microfibers as an internal curing agent in GGBFS-based cementless composites

This study investigated the impact of cellulose microfibers (CMFs) as an internal curing agent in ground granulated blast furnace slag (GGBFS)-based cementless composites with a focus on their role in improving hydration kinetics and microstructural characteristics. The test variable was the content of kenaf CMFs varying up to 1.5 wt% of the binder. The addition of saturated CMFs was found to decelerate initial heat release, but promote a higher cumulative heat release over time, indicating enhanced hydration efficacy. This was attributed to the efficient water retention and distribution capabilities of the CMFs. Thermogravimetric Analysis (TGA) and Fourier-Transform Infrared Spectroscopy (FT-IR) revealed that higher CMF concentrations led to greater weight loss around 100–400 °C and more distinct presence of Si-O bonds in the calcium silicate hydrate (C-S-H) gel, signifying more effective hydration. The inclusion of saturated CMFs also increased gel pores and decreased capillary pores, refining the microstructure. However, an excessive content of CMFs introduced larger lumen cavity pores, increasing overall porosity. Furthermore, the study highlights a significant environmental benefit of using cementless composites with CMFs, demonstrating a reduction in CO₂ emissions by up to 77.8 %. These findings underscore the potential of CMFs to not only enhance the structural performance of building materials but also improve their ecological footprint.