As the volume of polymer waste continues to grow, the development of methods for their processing and the creation of composites is an urgent task. In this work, the characteristics of sand–polymer composites based on reclaimed thermoplastics (1:3 mixture of polyolefins) are investigated. It was found that composites containing up to 75 wt% silica sand (100–300 μm) retained acceptable compressive strength (at least 25 MPa) at a strain of no more than 5%. Sand surface treatment improved the interaction between polymer and filler, increasing compressive strength by 10–15% and impact strength by 10% at 70–75 wt% of filler. The deformation and strength parameters of composites modified with carbon nanocomponents were investigated. The dependencies of compressive and bending strength on technological parameters of formation were obtained. The role of modifying components in appretization and reinforcement was shown. The introduction of technological lubricants improved homogeneity but reduced strength. The strengthening effect was related to the increase in the proportion of polymer interacting with the filler surface when the thickness of the polymer matrix reached the nanostate. The introduction of silica nanoparticles (up to 0.1 wt%) increased the compressive strength by 15%. However, the decrease in melt fluidity limited the degree of filling. The obtained composites are promising for application as structural materials in hull products used in limited climatic conditions.

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The machining of highly abrasive sand–polymer composites pose significant challenges due to rapid tool wear directly associated with the tool’s stress–strain state. This study provides a detailed analysis of the stress and strain distribution in a T15K6 carbide turning insert under contact loads generated during the cutting of SPCs with varying quartz content. The approach combines analytically derived contact stress distributions on the rake and flank faces with numerical modeling using the finite element method (ANSYS). This hybrid methodology enables the accurate evaluation of stress localization in critical tool regions without performing full-scale cutting simulations. A parametric series of simulations was carried out by varying the mass fraction of quartz in the composite. The results demonstrate an almost linear increase in the maximum equivalent (von Mises) stress with rising quartz content, described by σ_eq = 9.61·C_quartz + 232.41. For the base composition with 60% quartz, the maximum equivalent stress is approximately 812 MPa, corresponding to about 50% of the flexural strength of the T15K6 alloy and ensuring a safety margin of roughly two. However, as the quartz fraction approaches 85%, the stress level becomes close to the critical limit, indicating an elevated risk of tool failure. The proposed analytical-numerical approach provides an effective framework for assessing the stress–strain state of carbide cutting tools and can support the optimization of machining conditions for highly abrasive composite materials.