Effects of particle size on properties of engineering muck-based geopolymers: Optimization through sieving treatment

Effects of particle size on properties of engineering muck-based geopolymers: Optimization through sieving treatment

Engineering muck (EM), a common solid waste containing clay minerals, offers significant potential for resource utilization in building materials. The particle size of raw materials can significantly affect the performance of geopolymers. To improve the performance of the EM-based geopolymers, this study conducted sieving treatment and comparatively analyzed the influence mechanism of different particle sizes on the geopolymerization and its products. The particle sizes were categorized as LPS (1.18–2 mm), MPS (0.075–1.18 mm), and SPS (<0.075 mm). Experimental results revealed that EM soil particles of all three sizes contained clay minerals with varying compositions. As particle size decreased, the quartz content reduced while the clay mineral content increased. Upon calcination, LPS and MPS showed limited reactivity with alkaline solutions, resulting in geopolymers with surface cracks and large pores. In contrast, calcined SPS, due to its higher clay mineral content, achieved the highest amorphous phase content (90.61 %) and surface area (14.591 m²/g), enhancing its reactivity with alkaline solutions. This produced a dense microstructure with abundant geopolymer gel, yielding a 28-day compressive strength of 48 MPa, which was 8.9 times and 2.8 times higher than GP-L and GP-M, respectively. Additionally, compared to ordinary Portland cement (OPC), the EM-based geopolymers reduced CO₂ emissions by 60 %-69 % and energy consumption by 18 %-36 %, thereby reducing the environmental impact. This study provides a simple method for the optimization of EM as a raw material for geopolymers.

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