Effect of Calcium Carbide Residue on Strength Development along with Mechanisms of Cement-Stabilized Dredged Sludge

Abstract

The purpose of this research is to explore the feasibility of using calcium carbide residue (CCR), a by-product from acetylene gas production, as a solid alkaline activator on the strength development in CCR–Portland cement-stabilized dredged sludge (CPDS). The effects of cement content, CCR content and curing time on the strength development of CPDS were investigated using a series of unconfined compressive strength (UCS), pH and electric conductivity (EC) tests. Scanning electron microscopy and X-ray diffraction analyses were performed to gain additional insight into the mechanism of strength development. Meanwhile, the carbon footprints of CPDS were calculated. Following the results, it was found that CCR can significantly improve the strength of cemented dredged sludge. On the basis of the strength difference (ΔUCS) and strength growth rate (UCSgr), it was recommended that utilizing 20% cement with the addition of 20% CCR is the most effective way to develop the long-term strength of CPDS. In addition, the microstructural analysis verified that the optimum proportion of CCR benefits the formation of hydration products in CPDS, particularly needle-like gel ettringite, resulting in a less-porous and dense inter-locked structure. Furthermore, the solidification mechanism of CPDS was discussed and revealed. Finally, it was confirmed that CCR can be a sustainable alternative and effective green alkaline activator for the aim of improving cemented dredged sludge.

Investigation into the Rheological Properties and Microstructure of Silt/Crumb Rubber Compound-Modified Asphalt

“…As shown in ref. [28], |G*| also gradually increases when reduced frequency increases. This indicates that low temperatures and high frequencies can bring about a significant increase in the resistance of SILT-CRMA, in the case of repeated shearing.…”

Reusing Dredged Material through Stabilization with So-Called Bio-Enzyme Products

“…In recent studies, dredged material was treated with a blend of FA, PC, hydrated lime (HL) and fibers to produce compressed stabilized earth bricks (CSEBs) [20], while a report on the mixture of DM and recycled concrete concluded that mixtures containing 20% DM met the minimum road subgrade properties [21]. The stabilization mechanism and strengthening processes of these traditional stabilizers have been well-characterized in several studies [22][23][24][25], and the relationship between strength and water distribution was investigated using nuclear magnetic resonance spectroscopy [26]. Non-traditional stabilizers including ionic stabilizers, sulphonated limonene and enzyme emulsion are available in concentrated liquid forms, which are diluted with water prior to application and marketed as potential alternatives to traditional calcium-based stabilizers such as lime and cement [27,28].…”