Stabilization of Expansive Soil with Ceramic Marble Dust Waste Reused Sustainably: Microstructure, Performance, and Mechanism

The expansive soils have extreme swelling-shrinkage characteristics that undermine the foundations and pavements' serviceability. Simultaneously, ceramic and stone-processing sectors produce high amounts of marble dust, the disposal of which is not planned and is an environmental and land-management problem. This research paper will assess the sustainable re-utilization of ceramic marble dust waste as a microfiller in the stabilization of expansive soil, but to reinforce it further using synthetic polyester fibers. A systematic program that included compaction, shear strength, and California Bearing Ratio (CBR) and model footing tests was undertaken in order to measure density, stiffness, and bearing performance improvements. Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), and X-Ray Diffraction (XRD) of microstructure and minerals provided the means to explain the stabilization mechanism, and finite-element analyses of PLAXIS 2D were employed to confirm the behaviour of load-settlement. The findings indicate that marble dust acts mainly as a calcium-carbonate microfiller, pore structure refiner, and enhances particle packing, and polyester fibers act as tensile bridging of particles and deformation control. The use of new crystalline phases was not observed, which proved the improvement mechanism to be mainly physical but not chemical. The hybrid mixture, which had 30 wt.% marble dust and 1.0 wt.% fiber, gave the best performance, showing high density, strength, and settlement resistance. The numerical predictions were in good agreement with experimental trends. On the whole, the research shows that there is an ecologically friendly avenue of valorizing the waste of ceramic marble dust and enhancing the working of expansive soils based on the principle of microstructural densification and mechanical reinforcement.