Coupling effect of cement-stabilization and biopolymer-modification on the mechanical behavior of dredged sediment

Nowadays, biopolymer stabilization as a promising eco-friendly approach in soft ground improvement has attracted wide attentions. However, the feasibility of using biopolymer as a green additive of cement-stabilized dredged sediment (CDS) with high water content is still unknown. In this study, guar gum (GG) and xanthan gum (XG) were adopted as typical biopolymers, and a series of unconfined compressive strength (UCS), splitting tensile strength (STS) and scanning electron microscopy (SEM) tests were performed to evaluate the mechanical and microstructural properties of XG- and GG-modified CDSs considering several factors including biopolymer modification, binder–soil ratio and water–solid ratio. Furthermore, the micro-mechanisms revealing the evolutions of mechanical properties of biopolymer-modified CDS were analyzed. The results indicate that the addition of XG can effectively improve the strength of CDS, while the GG has a side effect. The XG content of 9% was recommended, which can improve the 7 d- and 28 d-UCSs by 196% and 51.8%, together with the 7 d- and 28 d-STSs by 118.3% and 42.2%, respectively. Increasing the binder–soil ratio or decreasing the water–solid ratio significantly improved the strength gaining but aggravated the brittleness characteristics of CDS. Adding XG to CDS contributed to the formation of microstructure with more compactness and higher cementation degrees of ordinary Portland cement (OPC)-XG-stabilized DS (CXDS). The micro-mechanism models revealing the interactions of multiple media including OPC cementation, biopolymer film bonding and bridging effects inside CXDS were proposed. The key findings confirm the feasibility of XG modification as a green and high-efficiency mean for improving the mechanical properties of CDS.