Industrial-Scale Production of Low-Cement Pressed Wall Materials from Shell Limestone Sawing Waste: Binder Efficiency, Contact Zone Evidence, and Techno-Economic Performance

Shell limestone sawing generates large quantities of porous carbonate waste that is difficult to reuse because of its high water demand and variable fine-particle content. This study evaluates an industrial-scale route for converting this waste into low-cement, vibration-compacted pressed wall materials at LLP “Firma Fial” in the Mangystau Region of Kazakhstan. The work combines industrial process documentation, compressive strength testing, binder intensity calculations, XRD phase identification, contact zone microhardness measurements, SEM observations, and a material cost comparison. Waste was crushed to below 5 mm without removing fines, moisture was checked before batching, and the mixtures were vibration-filled for 15–30 s at a compaction factor of approximately 2, followed by immediate demolding. Cement contents of 50, 75, and 110 kg/m3 produced 28-day strengths of 3.43, 4.90, and 7.36 MPa, respectively. The corresponding binder intensity was 14.6–15.3 kg m−3 MPa−1. XRD identified calcite as the dominant phase with minor dolomite and magnesite, while SEM and microhardness observations confirmed a distinct cement-paste/carbonate-aggregate interfacial region. The comparison with higher-strength reference concretes is interpreted cautiously because the strength ranges and compaction concepts differ. At 2023 prices, material cost decreased from KZT 24,785 (USD 54.32) to KZT 9982 (USD 21.87) per m3. The results demonstrate industrial feasibility while identifying mixture reproducibility, interfacial characterization, and full life-cycle assessment as priorities for further work.