Partial replacement of ordinary Portland cement with belite-rich cement to produce limestone calcined clay cement to regulate the hydration process, improve strength, and reduce carbon emissions

초록

Limestone-calcined clay cement (LC3) is gaining attention for its lower carbon emissions than traditional cement. This study aims to further reduce the carbon footprint of LC3 while enhancing its 28-day strength through the material design of Portland cement. We evaluated LC3 by replacing ordinary Portland cement (OPC) with beliterich cement (BRC) at substitution levels of 0 (B0), 1/3 (B1), 2/3 (B2), and 3/3 (B3). Properties were assessed over 1-56 days, alongside COQ emission analysis. The results indicate that increasing the BRC content extends the setting time. During the early stages (1-7 days), the compressive strength of the BRC samples was 11-39 % lower than that of the B0 samples. However, B1 outperformed B0 by Days 28 and 56, with strengths that were 6 % and 4 % greater, respectively. The early ultrasonic pulse velocity and resistivity decreased with increasing BRC. Thermogravimetric analysis revealed reduced chemically bound water and calcium hydroxide (CH) in the BRC samples. Hydration heat tests revealed that BRC prolonged the induction period and reduced the cumulative heat, maintaining stable C3S peak intensity, suggesting synergy between BRC and OPC. Fourier transform infrared and X-ray diffraction analyses confirmed a higher calcium silicate hydrate (CSH) content by Day 56 in B1 and reduced CH formation. Sustainability analysis revealed reduced COQ emissions per unit volume and strength, with B1 achieving a 5.9 % reduction. These findings suggest that LC3 with BRC offers improved strength and sustainability, positioning it as a promising low-carbon cement alternative.

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