Modification of cement-based circulating fluidized bed combustion slag: Physical grinding and chemical excitation.

This study investigates the effects of physical grinding (ball, impact, and jet milling) and chemical modification (using various dosages of Na 2 SO 4 , CaO, triethanolamine (TEA), and their composite modifiers) on CFBCS. The fluidity, flexural strength, compressive strength, and expansion rate of different modification methods were tested. Microstructural and phase composition analyses were conducted using X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, mercury intrusion porosimetry, and thermogravimetry-differential thermogravimetry. The results indicated that impact milling improved mortar fluidity by 2.9 % compared to ball milling, while jet milling reduced it by 5.7 %. Chemical modifications decreased paste fluidity but increased mortar strength and reduced expansion rates. Impact milling and jet milling improved 28-day compressive strength by 13.76 % and 16.01 %, respectively, and reduced the 90-day expansion rate by 0.007 % and 0.012 %, respectively. Composite chemical modification (CM-C) enhanced 28-day compressive strength by 23.88 % and reduced the 90-day expansion rate by 0.019 %. Microscopic analysis shows that modification reduced the pores and pore size of the mortar while increasing the hydration products. After TEA modification, rod-shaped AFt forms a reticulated structure, with C–S–H gel and CH crystals adhering to it. The hydration products of CFBCS mortar formed a network after jet milling, and the addition of composite modifiers resulted in a layered, dense structure. • Impact milling improved fluidity. • Combined modifiers reduced expansion. • Jet milling and modifiers improved hydration. [ABSTRACT FROM AUTHOR]