Characteristics on compressive strength and microstructure of high-strength cementitious composites with waste glass beads

This study investigated the potential of waste glass beads (WGB), a recycled porous lightweight material derived from waste glass, to enhance long-term curing of moisture-saturated cementitious construction materials. The macroscopic properties and microstructure development of a cement composite material blended with two types of WGB––spherical (B) and crushed (CB)––were analyzed. The primary objective was to provide practical guidelines for optimizing WGB utilization as a moisture release medium and thus contribute to sustainable concrete production by exploring waste glass applications. This study demonstrated the potential of WGB for improving strength and void structure and could help enhance the long-term durability of cement composites. Valuable insights were gained regarding the surface roughness and specific surface areas alongside curing methods to maximize WGB's effectiveness. The key contributions are as follows: (1) varying effects on high-strength concrete (HSC) strength with increased WGB content and surface roughness and specific surface areas were analyzed; (2) a proportional relationship between closed pore volume and modulus affecting macroscopic properties was revealed; (3) insights into hydration product presence in the ITZ and its relationship with WGB moisture content were gained; and (4) notable improvements in indentation tests for specimens with WGB were achieved, indicating enhanced ITZ hydration and increased density within both ITZ and paste.