Abstract: To improve the mechanical properties and deformation stability of stabilized sludge, a new type of eco-friendly curing agent with cement, slag, fly-ash and gypsum (CSFG) as materials and fiber reinforcement (FR) is developed. Through the unconfined compression test and permeability test, the effects of different CSFG contents (10%, 20%, 30%), different fiber lengths (0, 3, 6, 12 mm), and different fiber contents (0%, 0.2%, 0.4%, 0.8%) on the mechanical properties and permeability of the samples are compared and further analyzed. In addition, the micro mechanism of the CSFG-FR synergistic effect is analyzed and explored by X-ray diffraction (XRD), scanning electron microscope (SEM) and nuclear magnetic resonance (NMR). The main conclusions are as follows: (1) The mechanical properties of CSFG-FR stabilized samples are significantly improved, and the failure mode has changed from brittle failure to ductile failure. Moreover, the deformation properties are improved, while the improvement effect of permeability is inapparent. (2) The fiber has a critical content (0.4%), which plays a positive role on properties improvement when the fiber is less than the critical content and have a side effect by contrary when it exceeds the critical content. (3) Through forming a three-dimensional fiber network, the fiber can promote the distribution of hydrate and guide the hydrate to adhere to its surface, thus exerting the synergistic effect of CSFG-FR. The optimal fiber content is 0.4% and the optimal fiber length is 12 mm.

Key words: sludge stabilization, fiber reinforcement, CSFG curing agent, curing mechanism, engineering properties