Multiscale study on the effect of recycled glass fiber on the rheological, hydration, and mechanical properties of cement paste

Abstract

To enhance the application of recycled glass fiber (RGF) in Portland cement, it is essential to gain a comprehensive understanding of its interactions with the cement paste matrix. This study employs recycled glass fiber powder (RGFP) to explore the mechanisms by which RGF influence the properties of cement paste across nano to macro scales, and further analyzes the interrelationships among these scales. At the nanoscale, the interaction between RGFP particles and Ca^2 + ions in the cement pore solution was examined. At the microscale, the morphology, chemical composition, interfacial properties, and pore structure of the hydration products were characterized. At the macroscale, the effects of RGFP on the rheological behavior, hydration heat evolution, and strength of cement paste were analyzed. The results indicate that RGFP exhibits limited adsorption capacity for Ca²⁺, which hinders the nucleation and adhesion of C-S-H, thereby reducing the degree of hydration and weakening the interfacial bond with the cement matrix. Moreover, the incorporation of RGFP negatively affects the pore structure and decreases the compressive strength of the cement paste. However, due to its larger particle size and smooth surface, RGFP improves the rheological properties of the cement paste. Furthermore, the addition of 0.5 % RGF (by cement volume) enhances the flexural strength, as the fibers effectively bridge cracks during the pull-out process.