Hydration characteristics of waste catalysts used as pozzolanic materials

Abstract

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

The effects of SiO2/Na2O molar ratio on the characteristics of alkali-activated waste catalyst–metakaolin based geopolymers

“…Additionally, environmental laws concerning spent catalyst disposal have become stricter in recent years. Increasing demand for natural resources and a relative lack of environmentally acceptable solid waste disposal sites have motivated many municipalities in Taiwan to consider resource recovery as an alternative for detaching with spent catalysts [17]. However, a previous study reported that industrial solid wastes and byproducts containing silica and/or alumina, such as fly ash, can be used as pozzolanic components in geopolymerization [18,19].…”

Microstructural characterization of catalysis product of nanocement based materials: A review

“…The amount of the chemical compound presence in the cement hydration process might affect the filling ability of those hydration products to fulfil the capillary pores in cement system. The FTIR analysis for SFCC studied in previous [32] indicated the formation of hydrated calcium silicate of the C-S-H gel type as caused by nature alkaline activation of SFCC as the main reaction product. This result showed that the pozzolanic reaction has occurred in the cement-based sample and gave pore filling effect to the cement microstructure as more C-S-H gel produced in the reaction during cement hydration process.…”

Acoustic Emission and Ultrasonic Characteristics in the Failure Process of Cemented Waste Concrete-Coal Gangue Backfilling (CWCGB) under Uniaxial Loading

“…As can be seen from the microscopic image ( Figure 5), there are numerous tiny fractures in the ITZ between the coal gangue and paste in the static condition. e reason for this is that the mechanically crushed coal gangue has pozzolanic activity, and it reacts with Ca(OH) 2 produced by the hydration of cement as an alkali-aggregate reaction at the 600 d curing time [33,34]. is is also responsible for the low strength of the CGB.…”