<p>Belite cement (BC), which contains dicalcium silicate (C₂S) as its main mineral phase, has attracted increased attention due to several advantages, including a lower calcination temperature, a lower heat of hydration, and higher long-term strength. However, low hydration reaction rates and inadequate early-age strength necessitate improving C₂S by tailoring it into a fibrous morphology. Commonly, the synthesis of fibrous C₂S has depended on costly silicon sources, such as high-purity quartz powder and silica aerogels. To solve this issue, the fibrous C₂S was synthesized via the hydrothermal method using silica, tempered glass, and container glass in the present study. When tempered and container glass were utilized as silicon sources, a ball-milling pretreatment was required to reduce their particle size first. The silicon sources were mixed with water to form a slurry, which was then subjected to hydrothermal treatment. Upon completion of the hydrothermal process, the resulting material was calcined to yield C₂S. In this research, the parameters of the ball milling procedure, including the ball-to-material ratio, milling speed, and milling time, were investigated to obtain particles below 200 mesh. Moreover, the calcium-to-silicon ratio, water-to-solid ratio, and calcination temperature were also determined in the hydrothermal process. The results indicate that ball-to-material ratios of 5:1 and 10:1 at 160&#xa0;rpm for 12&#xa0;h were optimal for tempered glass and container glass, respectively, during ball milling. On the other hand, the optimal fibrous C₂S synthesis parameters for each silicon source were found to vary, reflecting the distinct characteristics of the glass types used.</p> Graphical abstract <p></p>