CSFG-FR协同作用改良淤泥固化土性能试验研究

为改良淤泥固化土力学特性，提高其变形稳定性，提出采用以水泥?矿渣?粉煤灰?石膏（CSFG, cement-slag-flyash-gypsum）为材料的新型环保固化剂，协同纤维加筋（FR）作用改良淤泥固化土。通过开展无侧限抗压试验和渗透试验，对比分析了不同CSFG掺量（10%、20%、30%）、不同纤维长度（0、3、6、12 mm）和纤维掺量（0%、0.2%、0.4%、0.8%）对试样力学性能和渗透性能的影响。此外，通过X射线衍射（XRD）、电镜扫描（SEM）和核磁共振试验（NMR）分析了CSFG-FR协同作用的微观机制，讨论了其协同作用机制。得到如下主要结论：CSFG-FR试样的力学性能有较为显著的提升，破坏模式从脆性破坏转变为韧性破坏，变形性能也得到改善，但渗透性能改良效果不明显；CSFG-FR中的纤维存在临界掺量（0.4%），当纤维小于临界掺量时发挥积极作用，超过时则会产生反作用；纤维通过形成三维纤维网络，促进水化物分布，引导水化物在其表面附着生长而发挥CSFG-FR协同作用，最佳纤维掺量为0.4%，最佳纤维长度为12 mm。

Experimental study on performance of sludge stabilized by CSFG-FR synergy

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.