Hydration characteristics of waste catalysts used as pozzolanic materials



This investigation examines the chemical and physical behaviors of waste catalyst (WC), a byproduct of the petroleum refining industry, used as a component of cement-based materials. WC was recycled as a pozzolanic material partially to replace cement to enhance the pozzolanic activity of pastes contained WC. Fourier transformation infrared spectroscopy (FTIR), differential thermal and thermogravimetric analysis (DTA/TGA) and 29Si magnetic angle spinning/nuclear magnetic resonance (29Si MAS/NMR) approaches were adopted to relate both the hydration products of pastes contained WC and the structural features to its cementitious activity. The cementitious activity of WC was evaluated by testing the compressive strength of blended cement pastes. The results demonstrate that the blended cements that contained 10% WC exhibited favorable cementitious activity owing to the formation of C-S-H C-A-H and C-A-S-H materials in the hydration products, and an increase in densification. The substitution of cement by WC would have an additional positive environmental impact because it would permit the recycling of a byproduct of the refinery industry in Taiwan that otherwise would remain in the environment as a waste product. © 2013 American Institute of Chemical Engineers Environ Prog, 33: 353–358, 2014