Title: Supplementary Cementitious Materials from Different Wastes

Author(s): Rimvydas Kaminskas, Irmantas Barauskas, and Edvinas Kazlauskas

Publication: Materials Journal

Volume: 120

Issue: 3

Appears on pages(s): 73-80

Keywords: hydration; portland cement; pozzolana; waste

DOI: 10.14359/51738684

Date: 5/1/2023

Abstract:
The main objective of this study was to investigate the possibility of using a mixture of two different wastes—spent catalyst from the oil cracking process and spent smectite clay from the alimentary oil bleaching process—as supplementary cementitious materials (SCMs). The spent catalyst was used as received, and the smectite clay waste was further thermally activated at 600°C. Both wastes were found to contain amorphous compounds and to have good pozzolanic activity. Fifteen wt. % of portland cement was replaced by these wastes mixed in different proportions. It was found that the additives from a mixture of these wastes accelerated the early hydration of the cement in a complex manner. The smectite clay component promotes the hydration reactions of calcium silicates, while the catalyst component activates the reaction of the aluminate-bearing phase. A similar complex trend was found for the compressive strength of the samples: the higher compressive strength of the cement samples produced the catalyst component at shorter periods of hydration, but as the duration of hydration increased to 28 days, a smectite clay component began to impart greater compressive strength. The mixture of 70 wt. % spent catalyst and 30 wt.% smectite clay waste was found to have the best strength properties, and up to 20 wt. % portland cement could be replaced using these admixtures.