The global cement industry faces a critical challenge of reducing its substantial carbon footprint while maintaining material performance. Portland cement production significantly contributes to global CO₂ emissions, necessitating innovative sustainable alternatives. This study evaluates the transformative potential of calcined natural pozzolans as a strategic approach to developing low-carbon cement. By systematically investigating the effects of calcined natural pozzolans derived from kaolinite and pyroclastic rocks on cement paste properties, the research demonstrates a promising pathway to environmentally efficient cement formulations. Utilizing advanced characterization techniques including XRD, TGA, SEM-EDX, and gas adsorption porosimetry, this study provides insights into hydration kinetics, compressive strength development, microstructural evolution, and porosity refinement. The results reveal that calcined natural pozzolans strategically enhance cement performance by accelerating hydration processes, improving compressive strength, and sophisticating microstructural characteristics. Notably, pastes incorporating pyroclastic rock pozzolans exhibited superior mechanical properties, with 28-day compressive strengths exceeding ordinary Portland cement by 35.2%. These findings not only validate the technical feasibility of natural pozzolan-based low-carbon cement but also underscore their potential to meaningfully reduce the construction industry’s environmental impact.

The incorporation of supplementary cementitious materials (SCMs) is a key strategy for enhancing the performance and sustainability of cement-based systems. This research examines the mechanical behavior, microstructural evolution, and durability-related properties of cementitious materials incorporating waste glass powder (WGP) and metakaolin (MK) as partial replacements of Portland cement. Cement pastes were evaluated for compressive strength at 7 and 28 days, while microstructural analysis at 28 days employed gas adsorption and scanning electron microscopy (SEM). Based on the compressive strength performance of the cement pastes, ternary WGP–MK mortars were assessed for consistency, flexural and compressive strength, water absorption, and porosity at 28 and 60 days. Results indicate that MK accelerates early-age strength, whereas WGP enhances long-term performance and pore structure refinement. Binary and ternary systems exhibited reduced accessible pore volume, enhanced microstructural homogeneity, and lower water absorption with curing time. The findings demonstrate that WGP-MK blends support clinker reduction without compromising performance, advancing circular economy goals in construction.

Rod-like zirconium diboride (ZrB ₂ ) was synthesized for the first time using concentrated solar energy. The process involved the preparation of a Zr/O/C/B complex by sol–gel preparation at 120 °C, followed by carbothermic reduction in a quartz-windowed solar reactor under an argon atmosphere at 1300 °C for 25 min. The structural, morphological, and thermal properties of the resulting ZrB ₂ were investigated by FTIR, XRD, SEM, TEM, and TGA/DSC. Phase transformations of the precursor at 1100, 1200, and 1300 °C confirmed the formation of hexagonal ZrB ₂ with minor zirconia residues. The final product exhibited nanorod morphology with well-defined crystal growth along the (001) plane and crystal size of 56.1 nm. These results highlight the effectiveness of concentrated solar energy in promoting the rapid and sustainable synthesis of advanced ceramics and demonstrate its potential for large-scale nanomaterial production.