Strength development of dredged sludge with different sodium hydroxide contents

Abstract

Granular blast furnace slag (GS) is a glassy substance formed when the slag melted in blast furnace ironmaking is not crystallized within time. An alkaline activator can show high hydraulic hardness in an alkaline environment. Using industrial wastes such as GS and fly ash (FA) to solidify dredged sludge (DS) is an economical and environmentally friendly solution. This study investigates the effectiveness of sodium hydroxide (SH) on the strength development of cement-bound industrial waste to stabilize DS. The effects of SH content on strength, atterberg limits, cohesion, and internal friction angle were analyzed. In addition, microstructural analysis was carried out by scanning electron microscopy (SEM) and x-ray diffraction experiments (XRD). Thermal gravimetry (TG) and derivative thermal gravimetry (DTG) was carried out to analyze the decomposition properties of the stabilized soil. The results show that SH's content significantly affects the solidified DS, and the UCS of stabilized soil increases with the increase in SH content. In addition, the SH content had no noticeable effect on the cohesion between particles. However, with the increase of SH content, the internal friction angle increased significantly, improving the solidified DS's shear strength.

Keywords:

• Granular blast furnace slag
• dredged sludge
• strength development

Acknowledgments

The authors are grateful for the study's financial support presented in this paper from the National Natural Science Foundation of China (Grant No. 41772303), the Shanghai Sailing Program (Grant No. 19YF1415500), and the National Natural Science Foundation of China (Grant No. 52108327).

Disclosure statement

The authors declare that they have no competing interests.