The low-carbon stabilization of dredged sludge remains a major challenge in geotechnical and environmental engineering, particularly when conventional cement-based binders are used at high dosages. In this study, a ternary solid-waste binder composed of circulating fluidized bed ash (CD), lithium slag (LS), and phosphorus slag (PS), denoted CDLP, was developed for the low-carbon stabilization of dredged sludge. An orthogonal design and sequential single-factor tests were used to identify the effects of the composite activator system, moisture content, binder content, cement replacement ratio, and ternary composition on unconfined compressive strength (UCS). The optimum conditions comprised a water-glass dosage of 4.0%, a dimensionless water-glass modulus of 1.2, a triisopropanolamine dosage of 0.7%, a zeolite dosage of 1.2%, a moisture content of 35%, a binder content of 16%, a cement replacement ratio of 60%, and a CD:LS:PS mass ratio of 2:6:2. The corresponding 28 d UCS reached 5.65 MPa. Compared with the same-condition ordinary Portland cement (OPC) control, the optimized CDLP mixture exhibited a 14.2% lower 7 d UCS but a 14.8% higher 28 d UCS. Semi-quantitative Rietveld refinement and scanning electron microscopy indicated that strength development was associated with alkaline dissolution, precipitation of poorly crystalline binding products and minor AFt, and the continuity and spatial distribution of particle-binding products. The optimized ternary composition compensated for the reduced OPC content through sustained later-age reactions. A screening life-cycle assessment showed reductions of 45.4% in volume-based carbon emissions and 11.3% in baseline material cost. After normalization by 28 d UCS, the corresponding reductions were 52.4% and 22.8%. Sensitivity analysis confirmed that the carbon advantage was robust, whereas the economic advantage remained dependent on activator prices. These results demonstrate the laboratory-scale mechanical and lower-carbon potential of the CDLP system.
