The consolidation properties of soil-bentonite (SB) backfills containing 20% of the weight of sodium-hexametaphosphate-modified calcium bentonite (SHMP-20CaB) and prepared with 0 mM to 1000 mM calcium chloride (CaCl₂) solution were evaluated. The results indicated that both consolidation stress and CaCl₂ concentration had significant effects on the consolidation behaviors of the SHMP-20CaB backfill. In general, an increase in consolidation stress resulted in a decrease in the void ratio (e) and in the coefficient of volume change (m_v), alongside an increase in the coefficient of consolidation (c_v). The increased CaCl₂ concentration yielded a dropped void ratio, and a nonlinear decreased compression index (C_c) and rebound index (C_s), respectively, from 0.18 to 0.13 and from 0.022 to 0.010, and a nonlinear increase c_v. A threshold CaCl₂ concentration of 100 mM was observed at the inflection points of the C_c, C_s, and c_v. In contrast, the m_v was insensitive to the CaCl₂ solutions. The deterioration in e, C_c, and C_s and the increase in c_v were the result of a compressed diffuse double layer of the bentonite by the CaCl₂ solution, which thus exerted certain negative effects on the consolidation behaviors of the SHMP-20CaB backfill.

Hybrid composites combining natural and synthetic fibers offer a pathway to sustainable structural materials, yet their performance is often limited by weak interfacial bonding and mechanical mismatches between constituents. Here, we address these challenges in bamboo/glass fiber hybrid epoxy composites through a sequential alkali and silane surface modification strategy. Alkali treatment removes amorphous lignin and hemicellulose, creating a roughened, cellulose-rich surface; subsequent grafting with (3-aminopropyl) triethoxysilane introduces an amino-functionalized interphase that covalently bonds with the epoxy matrix. This combined treatment increases the tensile strength of bamboo fibers by 51.2% and the interfacial shear strength by 136.6%, reaching values comparable to those of commercial glass fibers. The resulting hybrid composite exhibits a tensile strength of 485 MPa and a flexural modulus of 30.2 GPa, corresponding to improvements of 39.4% and 98.3%, respectively, over the unmodified hybrid system. Dynamic mechanical analysis further confirms an enhanced storage modulus across a wide temperature range. This work demonstrates that rational interfacial design via sequential functionalization offers a viable route to high-performance, lightweight, and structurally stable bamboo/glass fiber hybrid composites for sustainable engineering applications, such as reusable concrete formwork.