自燃煤矸石矿物掺合料对混凝土性能影响研究

发布时间：2019-01-24 08:17

【摘要】：煤矸石是在煤矿开采、洗煤与选煤过程中排出的工业固体废弃物,当藏匿在煤矸石中的可燃物在大自然中自燃后就形成了自燃煤矸石。以自燃煤矸石为基材进行磨细加工,达到一定细度可制备粉体材料—自燃煤矸石粉。本文针对国内突显出的优质混凝土掺合料短缺现状,依托国家自然基金委员会与神华集团有限公司联合资助项目(U1261122),研究自燃煤矸石粉作为混凝土掺合料的可行性以及对混凝土性能的影响,试图开发新品种混凝土掺合料,探索自燃煤矸石资源化应用的新途径。本文首先采用机械活化的方法,激发自燃煤矸石活性,根据自燃煤矸石粉-水泥胶砂流动度和强度试验结果,以及粉磨能耗确定自燃煤矸石的经济粉磨时间；在此基础上,选择自燃煤矸石粉掺量、减水剂品种和掺量三个影响因素,通过混凝土稠度和强度的正交试验,研究自燃煤矸石粉与减水剂的相容性问题；最后,以自燃煤矸石粉为掺合料配制混凝土,研究自燃煤矸石粉掺量对混凝土抗氯离子渗透和抗冻融性能的影响,为自燃煤矸石粉矿物掺合料的工程应用提供基础保证。本文得出如下结论：(1)阜新清河门矿自燃煤矸石易磨指数较高,粉磨时间为4-6min时,其活性指数大于Ⅰ级粉煤灰,但稍逊S95矿粉及水泥,胶砂流动度介于粉煤灰与矿粉之间,满足作为混凝土矿物掺合料的基本要求。(2)自燃煤矸石粉掺合料与不同品种减水剂复合双掺时,相容性是不同的,相容程度为：聚羧酸系萘系木质素系。其中自燃煤矸石粉与聚羧酸减水剂双掺时更能表现出优异的相容性能。(3)比较不同自燃煤矸石粉掺量、不同品种减水剂和掺量的混凝土稠度和强度规律时发现,自燃煤矸石粉掺量对拌合物粘聚性和保水性有一定程度的改善,对初始坍落度及经时损失影响不明显,但与萘系减水剂双掺时对混凝土7d抗压强度有一定影响,特别是后期强度增长幅度比纯水泥混凝土大；减水剂的品种和掺量对自燃煤矸石粉掺合料混凝土的工作性和强度影响都不明显。(4)自燃煤矸石粉少量掺入,虽然降低了混凝土的前期强度,但有利于混凝土的后期强度发展及耐久性能的提高。自燃煤矸石粉的掺入减少了硬化体中有害孔的含量,固化了侵入体系中的氯离子,掺量为35%时,60d龄期的混凝土氯离子渗透等级达到“极低”标准；自燃煤矸石粉掺量为15%时,混凝土的抗冻等级超过Fi200。只要控制好水胶比,保证混凝土具有较高的致密性,即使煤矸石掺合料的掺量较大,也能获得较高的强度和较好的抗冻性。
[Abstract]:Coal gangue is the industrial solid waste discharged in the process of coal mining, coal washing and coal preparation. When the combustible substance hidden in the coal gangue spontaneously burns in nature, it forms spontaneous combustion gangue. Spontaneous combustion gangue powder can be prepared by grinding coal gangue with certain fineness. In view of the shortage of high quality concrete admixture in China, this paper relies on the joint funded project (U1261122) by the National Natural Fund Committee and Shenhua Group Co., Ltd. The feasibility of spontaneous combustion coal gangue powder as concrete admixture and its influence on concrete performance are studied. The author tries to develop new concrete admixture and to explore a new way for the application of spontaneous combustion coal gangue. In this paper, the method of mechanical activation is used to stimulate the activity of spontaneous combustion coal gangue. The economic grinding time of spontaneous combustion coal gangue is determined according to the test results of flowability and strength of spontaneous combustion coal gangue powder and cement sand, and the energy consumption of grinding. On this basis, the compatibility of spontaneous combustion coal gangue powder and water reducer is studied by orthogonal test of consistency and strength of concrete. Finally, the effect of the content of spontaneous combustion coal gangue powder on the resistance to chloride ion permeation and freeze-thaw resistance of concrete is studied, which provides the basic guarantee for the engineering application of the mineral admixture of spontaneous combustion coal gangue powder. The conclusions are as follows: (1) when the grinding time is 4-6min, the activity index of spontaneous combustion gangue in Fuxin Qinghemen Mine is higher than that of Grade 鈪，

本文编号：2414291