LAUSR

Abstract A growing number of spent petroleum refining catalysts, SPC, were mainly disposed in landfills, which has brought about serious occupation of land resources and environmental security risks. In this paper, the effects of SPC powders on the workability, development of mechanical property, microstructure and the environmental safety with the incorporation of SPC (≤5 wt%) in the blended cement were systematically researched. The results indicated that the SPC powders should be regarded as heavy metals-polluted materials due to the plenty of heavy metals in SPC powders: 5804.81 ppm Ni, 2559.72 ppm V, 2429.83 ppm Sb. And the incorporation of the SPC powders resulted in the increase of the water requirements of standard consistency due to the relatively high Blaine fineness and porous micromorphology of SPC powders, but the addition of polycarboxylic acid water reducer improved effectively the reduced workability of the blended cement. It was also demonstrated that only the incorporation of 0.5% SPC powder leads to the accelerated setting time and early strength. The incorporation of SPC powders up to 5.0% all exhibited increasing enhancement influence on the long-term mechanical strength. These findings are well consistent with the subsequent analyses of non-evaporable water content and XRD. Meanwhile, the convincing evidences were presented by the SEM coupled with EDS to illustrate the effects of filling, nucleation, pozzolana and particle-reinforcement of SPC powders on the blended cement. The leaching toxicity tests also suggested that the disposal of SPC powders as cement admixture was quite unhazardous to the environment safety during the age of 28 days. However, the specific application environments, the long-term durability and the aggressive environment safety of utilizing SPC powders in cement need to further study.