Stabilization of Dredged Sediment Using Activated Binary Cement Incorporating Nanoparticles

Abstract

This study investigated the use of portland cement (PC)–ground-granulated blast-furnace slag (GGBS) binary cement (BC), which was improved by chemical activation and nanomodification, as a potential alternative to PC for stabilization of dredged sediment (DS). The activators of Na2SiO3 (SM), Ca(OH)2 (CH), Na2SO4 (SS), and nanomodifiers of nano-SiO2 (NS) and nano-MgO (NM) were used to improve the strength gaining of BC-stabilized DS (BCDS). A series of unconfined compressive strength (UCS), X-ray diffraction (XRD), and scanning electron microscopy (SEM) tests were conducted to investigate the strength development and associated micromechanisms of nanomodified and activated BCDS. The results indicated that chemical activation can effectively improve the UCS of BCDS, and optimum single activator contents of SM, CH, and SS were respectively 6%, 4%, and 10%. Composite activators SM/SS with mass ratio of 1/9 exhibited more advantages than a single activator. Nanomodification can further improve the UCS of SM/SS-BCDS. The optimum single nanoparticle contents of NS and NM for SM/SS-BCDS were 6% and 8%, respectively. Compared with a single nanoparticle, composite nanoparticles NS/NM with mass ratio of 5/5 were more effective in improving UCS of SM/SS-BCDS. The 15% optimum NS/NM-SM/SS-BC can be used to replace 30% PC for DS stabilization. XRD and SEM results confirmed that the main hydration products of NS/NM-SM/SS-BCDS were calcium silicate hydrate (CSH), calcium aluminate hydrate (CAH), and ettringite, which contributed to the strength enhancing.