硅藻土调质污泥制备水硬性胶凝材料试验研究

Experimental Research on the Preparation of Hydraulic Cementing Material from Diatomite Sludge

为了改善水硬性凝胶材料的力学性能,提高污泥的处置率,选用硅藻土等材料对污泥进行调质处理,利用张家口充足的太阳能及风能自然干化调质污泥。对干化后的污泥焚烧并粉磨制灰,通过胶砂强度对比试验及火山灰活性试验,分析调质污泥灰的火山灰活性。通过分别掺加同等质量的硅藻土、粉煤灰、页岩和沸石调质的污泥灰,测试其火山灰活性并进行水泥技术性能试验及胶砂收缩率试验,结合XRD及SEM进行微观的活性产生机理分析。对硅藻土调质污泥灰进行水泥技术性能试验及胶砂收缩率试验等试验,分析其取代部分水泥作为水硬性胶凝材料后的各项性能指标。试验结果表明:随硅藻土掺量的增加,污泥灰的火山灰活性先增加后趋于平缓,当掺量为9%,抗压强度比达到最高为87.3%;污泥中掺9%的硅藻土可获得较好的干化效果和最佳的火山灰活性;同掺量情况下硅藻土较粉煤灰、页岩、沸石调质的污泥灰具备更高的火山灰活性,且调制后的污泥灰制备水硬性胶凝材料其部分性能优于水泥,收缩率也较纯水泥更小。X射线衍射分析可见,未煅烧硅藻土含有石膏、石英及白云母晶体,煅烧过的硅藻土的石膏衍射峰消失,石英的各衍射次峰得到削弱。硅藻土与污泥混合搅拌干化煅烧后,石英晶体程度变弱。整体来看单烧及与污泥混合煅烧的硅藻土衍射图中尖锐的衍射峰较少,平整度高,活化程度高。SEM分析可见未煅烧硅藻土藻体壁上分布着排列整齐,大小均匀的微孔。经煅烧后其表面变得粗糙,覆盖着的无定形物质变得分散,增大了硅藻土与氢氧化钙反应时的接触面积,利于其火山灰活性的发挥。与污泥混烧的硅藻土藻体破坏程度较重,所见多为硅藻碎片,火山灰活性得以充分发挥。

In order to improve the mechanical properties of the hydraulic gel material and increase the disposal rate of the sludge,materials such as diatomaceous earth are selected to temper the sludge,and the tempered sludge is naturally dried by using the abundant solar and wind energy in Zhangjiakou.The dried sludge is incinerated and ground to produce ash,and the volcanic ash activity of the tempered sludge ash is analyzed by means of a comparative gelling strength test and a volcanic ash activity test.The volcanic ash activity is tested by mixing the same quality of diatomaceous earth,fly ash,shale and zeolite with the tempered sludge ash,and the technical performance of the ce⁃ment and the shrinkage of the cement sand are tested.The diatomaceous earth tempered sludge ash is tested for technical cement properties and sand shrinkage to analyze the performance of the cement as a hydraulic cementing material after it has been partially replaced.The test results show that the volcanic ash activity of the sludge ash first increases and then tends to level off with the increase in diatomaceous earth admixture,and the compressive strength ratio reaches a maximum of 87.3%when the admixture is 9%;the sludge admixture of 9%diatoma⁃ceous earth can obtain better drying effect and the best volcanic ash activity;the diatomaceous earth has higher volcanic ash activity than the sludge ash tempered with fly ash,shale and zeolite at the same admixture,and the modulated X-ray diffraction analysis shows that the uncal⁃cined diatomaceous earth contains gypsum,quartz and muscovite crystals,while the gypsum diffraction peaks of the calcined diatomaceous earth disappear and the secondary diffraction peaks of quartz are weakened.When the diatomaceous earth is mixed with sludge and dried and calcined,the quartz crystals become weaker.The SEM analysis shows that the walls of the uncalcined diatomaceous earth are covered with well-arranged,uniformly sized micro-pores.After calcination,the surface becomes rough and the amorphous material covered with it becomes dispersed,which increases the contact area between diatomite and calcium hydroxide and facilitates its volcanic ash activity.The diatomaceous algae mixed with the sludge are more heavily damaged and are mostly seen as diatom fragments,allowing the volcanic ash activity to be fully exploited.