Investigation into the formulation and properties of carbon nanotubes and nanosilica-enhanced cement slurry composites for well sealing

ABSTRACT This research investigates the performance enhancement of cement slurry composites for well-sealing applications through the incorporation of CNTs and NS. Experimental results revealed that the optimized hybrid composite (M3), containing 0.5% CNTs and 1% NS, achieved a compressive strength of 63.5 MPa at 7 days, a 64.39% improvement over the control sample (B, 38.6 MPa). Flexural strength increased by 62.95%, reaching 8.8 MPa. Triaxial testing demonstrated a peak strength of 71.6 MPa under a confining pressure of 10 MPa, highlighting the composite's superior mechanical stability. Microstructural analysis confirmed that CNTs bridged microcracks, while NS filled voids, reducing the average pore size from 120 nm (B) to 45 nm (M3) and total porosity from 18.5% to 9.8%. XRD analysis showed an 85% reduction in CH content, with significant C-S-H formation contributing to improved durability. Stability tests indicated negligible free water (<0.1%) and a density difference of 0.01 g/cm3, confirming excellent homogeneity. These findings demonstrate that the synergistic use of CNTs and NS significantly enhances the mechanical, microstructural, and durability properties of cementitious materials, providing a promising solution for high-performance well-sealing applications.