The influence of secondary aluminum ash sintering and grinding fine powder on the mechanical properties and shrinkage characteristics of Portland cement matrix

In order to utilize the absorption capacity of secondary aluminum ash in cement industry, and achieve the carbon reduction and emission reduction goals of the cement industry, the influence of different fineness and content of secondary aluminum ash sintering and grinding fine powder (MP) on the mechanical properties and shrinkage characteristics of Portland cement matrix was studied. Microstructural analysis was conducted using techniques such as XRD, TG, SEM, BET, and XPS. The results indicate that increasing the fineness and content of MP can delay the hydration process of the Portland cement matrix, leading to elevated porosity, and consequently deteriorate the early mechanical properties. The study also found that the hydrolysis of AlN in the hardened Portland cement matrix to produce NH3 intensifies the early expansion deformation of the Portland cement matrix. At the same time, the delay of hydration reaction causes a decrease in the content of hydration products such as AFt and an increase in porosity, thereby exacerbating the long-term shrinkage deformation of the Portland cement matrix. In addition, ICP and XPS analysis showed that the content of heavy metals and harmful substances in the Portland cement matrix was relatively low, meeting the relevant standards for harmless treatment.