The influence of fiber reinforcement on the physico-mechanical properties and microstructure of artificial stones with marble and quartzite waste aggregates

This study fabricated artificial stone samples using marble (carbonate-based) and quartzite (siliceous-based) waste aggregates, their corresponding fine powders, and Unsaturated Polyester Resin (UPR) via the Vacuum, Vibration, and Compression (VVC) method. After evaluating three resin percentages for each aggregate, the optimal formulations- Artificial Marble with 10 wt% resin (AM-10R) and Artificial Quartzite with 12 wt% resin (AQ-12R) were reinforced with Polypropylene (PP) and Glass fibers (GF). Different results were observed despite identical processing conditions. Fiber reinforcement in artificial quartzite maintained compressive strength (up to + 5% relative to the control) and showed a trend toward improved flexural strength (up to + 12.6% in the optimal formulation). In contrast, artificial marble exhibited significant reductions in compressive strength (16.5–22.8%) and flexural strength (4–21%), primarily attributed to increased porosity from 2.75% to 5.83%. Laser particle size analysis attributed this divergence to the different powder characteristics. The marble powder was significantly finer due to marble’s lower hardness, resulting in a stiffer resin-powder mixture with reduced workability. This impeded efficient air removal during the VVC process. The addition of fibers further worsened this issue in the marble-based composite, leading to higher porosity and diminished reinforcement efficiency. Therefore, Effective fiber reinforcement for strength improvement depends on precise porosity control through optimized manufacturing parameters, which is highly dependent on the aggregate-powder system’s properties. These findings provide practical guidance for producing stronger, eco-friendly artificial stones from industrial waste using optimized fiber–resin systems.