We investigated the impact of CaCO₃ addition on the density and compressive strength of calcium aluminate cement (CAC)-based cementitious materials in binder jetting additive manufacturing (BJAM). To confirm the formation of a uniform powder bed, we examined the powder flowability and powder bed density for CaCO₃ contents ranging from 0 to 20 wt.%. Specifically, powders with avalanche angles between 40.1–45.6° formed a uniform powder bed density with a standard deviation within 1%. Thus, a 3D printing specimen (green body) fabricated via BJAM exhibited dimensional accuracy of less than 1% across the entire plane. Additionally, we measured the hydration characteristics of CAC and the changes in compressive strength over 30 days with the addition of CaCO₃. The results indicate that the addition of CaCO₃ to CAC-based cementitious materials forms multimodal powders that enhance the density of both the powder bed and the green body. Furthermore, CaCO₃ promotes the formation of highly crystalline monocarbonate (C₄AcH₁₁) and stable hydrate (C₃AH₆), effectively inhibiting the conversion of CAC and showing compressive strengths of up to 5.2 MPa. These findings suggest a strong potential for expanding the use of BJAM across various applications, including complex casting molds, cores, catalyst supports, and functional architectural interiors.

The cement industry is an energy-intensive sector with significant CO 2 emissions owing to the high-temperature calcination processes and fuel combustion involved in clinker production. As the realization of carbon neutrality accelerates, the introduction of fuels to replace existing fossil fuels is being deliberated for the cement sector. In the domestic cement industry, various waste-derived alternative fuels, such as waste synthetic resins, waste tires, and waste wood, are utilized. This can contribute to the reduction of greenhouse gas emissions and promote resource recycling. As of 2021, the domestic cement industry has used approximately 2.245 million tons of the alternative fuels, accounting for 35 % of the total fuel consumption in the cement industry. Alternative fuels emit lower CO 2 than fossil fuels, such as bituminous coal. However, the domestic utilization rate of alternative fuels is low compared to that of major European countries. Accordingly, a multifaceted approach, includes institutional improvement, quality control, and supply and demand stabilization is required. This study investigated the current status of alternative fuel use in the domestic cement industry, overseas applications, and the characteristics of each fuel. Additionally, it explored ways to utilize carbon-free fuels such as hydrogen and ammonia to realize carbon neutrality in the cement industry in the future.

요 약 본 연구는 다양한 산업부산물을 활용하여 고강도 클링커를 제조하기 위해 원료 배합 설계 및 이에 따른 클링커 주요 광물상(C3S, C2S, C3A, C4AF)의 형성 특성을 분석하였다. 실험을 통해 원료 대체율 및 Modulus 조건(LSF, SM, IM)이 클링커의 주요 광물상의 형성과 물 리적 특성에 미치는 영향을 확인하였다. 소성온도 1,500 ℃, LSF 100, SM 2.7, IM 1.5의 Modulus 조건에서 제조된 A-1 클링커는 C3S 생 성량이 75.0 %으로 확인되었으며

Many technological fields have adopted composites with active material–support configurations, where the active materials dictate the catalytic activity, and the supports improve the properties. Hexagonal boron nitride (h-BN) is a promising and highly stable support material with limited applications because it is difficult to modify. In this work, a facile method for the etching of h-BN was achieved using metal oxide (MO_X) nanoparticles. The nanoporous structure of etched h-BN was revealed by selective removal of MO_X on the surface; as a result, the specific surface area and pore volume increased more than two-fold. Then, to verify the effect of the nanoporous structure, etched h-BN was used to support the catalyst because the nanoporous structure has an advantage in dispersing the nanoparticles. Fabricated etched h-BN-added catalysts exhibited high performance in N₂O conversion. This high performance was attributed to the changed oxidation states of metal cations by interaction-etched h-BN using MO_X nanoparticles. This study serves as a basis for the development of nanocomposites with various cations and supports for catalytic reaction systems.