【作者】 陶珍东；

【导师】 耿浩然；

【作者基本信息】 山东大学 ， 材料加工工程， 2005， 博士

【摘要】 自然资源的大量消耗和不合理利用造成了自然资源的日益短缺。充分利用各种废料、努力节约自然资源已成为工业生产中的方向之一。废弃混凝土作为建筑施工和拆除旧建筑产生的废料,弃置不用既会造成环境污染,又是巨大的资源浪费。多年来,人们对废弃混凝土的再利用进行了大量研究,并取得了许多研究成果。迄今为止,废弃混凝土的再利用研究大多是再生骨料混凝土的研究,但废弃混凝土中的胶凝基质组分-硬化水泥浆体(HCP)用于再生混凝土存在着许多问题,HCP在水泥生产中的再利用也未见研究报道。将废弃混凝土骨料分离后形成的以HCP为主要组成的细废弃混凝土部分(FWC)用作为水泥混合材料或水泥原料,可使它们得到科学、有效的合理利用,并节省天然原料资源,实现废弃物料资源化。这对于我国经济的长期可持续发展无疑具有重要的社会意义。本文进行了废弃混凝土骨料分离方法、分离后的FWC进行机械力化学活化后作为水泥混合材料制备水泥和作为水泥原料煅烧水泥熟料的试验研究,分析和探讨了FWC在熟料煅烧、水泥粉磨和水泥水化过程中的作用机理,旨在为FWC在水泥生产中的再利用提供理论和实践依据。本试验研究分为废弃混凝土骨料与HCP的分离、分离后的FWC作水泥混合材料和作水泥原料进行熟料煅烧三个主要部分。废弃混凝土骨料与HCP的有效分离是二部分材料合理再利用的关键。采用了表面活性剂处理和热处理二种方法结合机械粉碎进行了废弃混凝土骨料与HCP的分离试验研究。试验结果表明,掺加适当的表面活性剂可明显提高废弃混凝土骨料与PHC的分离效率,但阴离子表面活性剂木质素磺酸盐(CLS)、十二烷基硫酸钠(SLS)和强极性表面活性剂三乙醇胺(TEA)的分离效果比非极性表面活性剂好得多,其原因是它们在骨料与基质界面上的定向吸附更有效地降低了界面结合能,因而明显降低了界面结合强度。热处理温度对骨料和基质的分离效率有显著影响。热处理温度较低时,分离效率提高幅度不大;但500℃热处理后,分离效率显著提高。振动磨和球磨机的粉碎分离效率存在明显差别。粉碎分离后的FWC收率、化学组成及其粒度分布的综合测定结果表明,振动磨的粉碎分离效率优于球磨机粉碎。对于掺加表面活性剂情形,后者的FWC收率均高于前者,但较大颗粒含量及SiO2含量也高于前者。对于热处理情形,处理温度较低时,后者的FWC收率高于前者;500℃高温热处理时,FWC收率明显低于前者。球磨粉碎的FWC中较大粒度的物料含量明显大于振动摘要磨粉碎。结果表明,球磨粉碎时进入FWC的骨料比例高于振动磨粉碎,其原因是研磨介质对物料的体积粉碎使骨料表面较多的棱角突出部分发生结构破坏和断裂从而成为小颗粒。 根据热膨胀和水化物脱水现象首次提出了界面疏松区模型。该模型较好地解释了骨料与胶凝组分基质在热膨胀应力、HCP水化物受热脱水条件下的分离机理. FWC作水泥混合材料时,在相同粉磨条件下,水泥的粉磨效率明显提高,表现在0.Osmm方孔筛筛余减小、比表面积提高及微细颗粒含t增大。FWC较低的Bond粉碎功指数Wi证明其易磨性较好,其中表面活性剂CLS和TEA处理及500℃热处理的易磨性相对更好。试验结果表明,掺加上述表面活性剂处理的FWC磨制的水泥中,小于10 pm的颗粒含t比未经处理的提高60%以上,28天强度提高10%以上;掺加15%500℃处理的FWC的水泥强度比未处理的提高近15%,与纯熟料水泥相差甚小。其原因是表面活性剂的助磨作用减少了用于破坏颗粒团聚体的无效功耗;高温热处理后的FWC结构疏松,强度降低。 首次提出了用Wi表征物料粉碎动力学的新方法。该方法可更直观地反映粉磨速度与物料易磨性的密切关系。根据料层粉碎理论和选择性粉碎机理,从理论上解释了FWC中砂粒所含结晶51 02在水泥粉磨过程中对硬化HCP水化物或其脱水相的微粉磨介质作用, FWC的掺入量增大时,水泥的标准稠度需水量有所增大,胶砂流动度相应减小,凝结时间相对延长,各龄期强度也相应降低,但强度降低幅度小于或远小于其掺入量比例,掺入高温热处理的FWC的效果尤为明显。这表明FWC的水化活性虽不及水泥熟料,但的确具有较强的水化能力和较好的胶凝性.掺加CLS和TEA处理及500℃热处理的FWC的水泥各项物理性能都较好。这是因为,一方面,FWC易磨性的改善使水泥中细颗粒增多,因而提高了水化速率;另一方面,高温热处理过程和粉磨过程中的机械力化学效应引发的水化物脱水从结构本质上提高了其水化活性. 首次提出了HCP新生态脱水相加快熟料锻烧速度和水泥水化速度的观点.粉磨时物料细化过程的加速促进并加强了机械力化学效应,反过来,机械力化学效应又强化了水化物或其脱水相更快地发生结构或相变化,因而生成了更多的新生态物质。这些新生态物质较多的结构缺陷和热力学高度不稳定是其水化活性较高的本质原因。同时,较多的细颗粒不但自身水化速度快,还均匀地分散填充于硬化浆体中,使硬化浆体中大孔数量显著减少,保证了硬化浆体的结构均匀性和致密性。山东大学博士学位论文一废弃混凝土机械力化学活化再利用研究 与常规原料配合的生料相比,FWC配制的生料的易烧性稍差,并且随FWC配合?更多还原

【Abstract】 Great quantities of consumption and unreasonable utilization of natural resources have resulted in its shortage more and more; so, the mankind is being confronted with the serious resources crisis. It has become the one of direction for industry production to utilize fully various industrial wastes and to save the natural resources as much as possible. As a sort of waste produced by demolishing old buildings, waste concrete will result in serious environment pollution if it is not reutilized. At the same time, this also is vast resource extravagance. Ones have carried out a great of studies on the reutilization of waste concrete, and have obtained many achievements. So far, however, these investigations are focused to the recycling aggregate concrete, which is feasible in technique and economy, i.e. to utilize the coarse aggregate separated from waste concrete as recycling aggregate to produce recycling aggregate concrete. But, it exits a series of questions to utilize the binding matrix component (hardened cement paste—HCP) in waste concrete for recycling aggregate concrete production, and no report on utilizing HCP in cement manufacture has been seen. It is a scientific and reasonable method for saving the natural resources that to utilize the fine waste concrete (FWC)formed from separation, which is composed mainly of HCP, as admixture to produce cement and as raw material to burning clinker. The experimental studies on the methods separating coarse aggregate from HCP, using FWC as admixture and raw material in cement production were carried out in this paper, and the mechanisms of FWC in the clinker burning, cement grinding and cement hydration were analyzed in order to supply the theoretical and practical basis for the reutilization of FWC in cement manufacture.The experimental study is divided to three sections, i.e. to separate coarse aggregate form binding matrix by different methods, to utilize FWC as admixture to prepare cement and raw material to burning clinker.The key to reutilize reasonably waste concrete is to effectively separae the coarse aggregate and FWC. The separation experiments were carried out by combining surface active agents treatment and heat treatment of waste concrete with mechanical pulverization. The experimental results indicate that the separating efficiency of waste concrete increases significantly by adding suitable surface active agents. It is found that the effects of anion typed surface active agents Calcium Lignie Sulphonate (CLS) and Sodium Lauryl sulfate (SLS), and strong polar surface active agent Triethanolamine (TEA) are muchbetter than that of non-polar surface active agent. The reason is that they adsorb orientably on the interface of aggregate and binding matrix so that deduce efficiently the interface energy and the interfacial binding strength. The heat treatment temperature has a significant influence on the separating efficiency. When the temperature lower, the separating efficiency only increases slightly; After treated at 500℃, the separating efficiency increases remarkably, which is because the interfacial strength decreases evidently resulted from heat expansion and dehydration of the hydrates in HCP.The separating efficiency of vibrating mill is different evidently from that of ball mill. It is found from comprehensive evaluation of recovery of FWC that the separating efficiency of vibrating mill is higher than that of ball mill. For the case of adding surface active agents, FWC recovery of the latter is higher than that of the former, but the contents of larger particles and SiO2 in the latter are higher than that in the former. For the case of heat treatment, FWC recovery of the latter is higher than that of the former when treated at lower temperature; Whereas the result is opposite when treated at 500℃. In addition, the content of larger particles for ball milling is higher evidently than that for vibrating milling. The results indicate that, more aggregate particles enter into FWC for the case of ball milling because the volume pulverization makes more更多还原