生石灰对理化复合法处理淤泥浆效率的影响研究

改性淤泥固化土应用于填方工程既能弥补砂石填料供应短缺的困境，还能解决大宗疏浚淤泥的弃置难题。但当淤泥含水率超高（＞300%）时，纯水泥固化法处理效果极差，而采用絮凝调理联合化学固化的理化复合法可有效解决此类问题。鉴于生石灰具有絮凝和固化双重功效，采用生石灰替代部分水泥可能会进一步提高淤泥浆的理化复合法处理效率。通过十字板剪切试验研究了生石灰替代比对高含水率淤泥浆理化复合法处理效率的影响规律，并通过X射线衍射（XRD）和场发射扫描电镜（FESEM）试验从微观层面揭示了其固化机制。结果表明：生石灰对淤泥浆理化复合法处理效率会产生较大影响，且存在一个最优生石灰替代比，在最优替代比条件下生石灰能显著发挥絮凝和固化双重功效，并有效提高处理后淤泥的早期和晚期强度；从微观试验分析，最优替代比下处理后的淤泥样生成的CSH/CAH/CASH凝胶和钙矾石等水化产物数量最多，孔隙间隙也最小。因此，实际工程中运用理化复合法处理高含水率淤泥浆时，可采用生石灰替代部分水泥以提高处理效率。

Effect of quicklime on solidification efficiency of mud slurry treated by physicochemical composite method

Application of cement-solidified mud to filling projects can mitigate the local scarcity of sand and gravel filling material and dispose of significant volumes of dredged mud. Nevertheless, when the dredged mud is at extra-high water content (>300%), the treatment efficiency of pure chemical solidification becomes very low. However, such problems can be effectively solved by treating mud slurry using the physicochemical composite method. As the quicklime has both the effect of flocculant and solidification agent, using quicklime to replace part of the cement may further increase the treatment efficiency. In this paper, the effect law of the replacement ratio of quicklime on physicochemical composite treatment of dredged mud slurries was studied via vane shear tests, and its solidification mechanism was revealed by XRD and FESEM tests. The results show that quicklime significantly impacts on the physicochemical composite treatment effect, and there is an optimal replacement ratio. Under this optimal replacement ratio, the quicklime can exert the dual effects of flocculation and solidification, which effectively increases the earlier and later strength of the treated mud specimens. From the microscopic test results, the treated mud samples at this optimal replacement ratio produce the highest amount of CSH/CAH/CASH, ettringite and other hydrated cementitious materials with the smallest pore gap. Therefore, quicklime can be used to replace part of the cement during the physicochemical composite treatment of dredged mud slurries in the actual project.