【作者】 段晓牧；

【导师】 夏军武；

【作者基本信息】 中国矿业大学 ， 防灾减灾工程及防护工程， 2014， 博士

【摘要】 煤矸石作为我国目前年排放量和累计存量最大的工业废弃物之一，它的堆放方式和处理过程对周围环境产生重要影响，因此实现煤矸石的建材资源化是实现煤矸石可再生资源利用的有效途径。本文以自燃和非自燃煤矸石为混凝土的粗、细集料，采用理论数学模型、物理力学试验及光纤传感技术等理论和方法，研究了煤矸石集料的掺入对水泥混凝土微观结构和宏观物理力学性能的影响，分析了煤矸石集料混凝土的基本力学性能和早期收缩性能，得到了煤矸石集料品质的评价模型。论文的研究成果将对煤矸石作为混凝土集料的选用原则和煤矸石集料混凝土的设计、应用和推广等方面提供科学的理论基础。运用物相分析方法、材料微观形貌学方法研究了煤矸石细集料的活性对混凝土微观结构的影响。通过煤矸石细集料-水泥浆体水化产物的物相分析可知，自燃煤矸石细集料中活性SiO2和Al2O3能够发生二次水化反应，并生成水石榴石、水钙沸石和钙铁榴石等新物质；通过微观形貌分析，煤矸石细集料活性反应后，水化产物相互交联，形成间断的、孔隙较大的骨架网状体系并填充于微观孔隙和微裂缝之中，使微观结构不够致密，无法有效地改善水泥基材料的微观结构特征。通过4组配合比、3种煤矸石细集料掺量和3个龄期的450个煤矸石细集料-水泥浆体试块的抗压、抗折强度试验可知，自燃煤矸石的活性反应能够提高水泥基体材料的早期抗压强度，但对其后期抗压强度的影响不明显。煤矸石细集料和水泥浆体的强度协调对煤矸石细集料-水泥浆体宏观性能的发展最为有利。采用XRD、SEM、EDXA、MIP等多种测试技术，研究了煤矸石集料混凝土界面结构的微观形貌特征、化学元素分布特征、孔结构特征及显微硬度变化，得到了自燃和非自燃煤矸石集料-水泥石基体的界面结构特征；基于材料孔隙学、混凝土细微观结构学等理论，揭示了两种煤矸石集料与水泥石基体的物理、化学作用机理，构建了煤矸石集料混凝土的界面结构模型。通过材料力学试验，以煤矸石作为混凝土粗、细集料为研究对象，考虑了煤矸石种类、颗粒级配、预处理方式、养护条件等4种影响因素和2种水灰比，进行了288个试块的材料力学性能试验，建立了煤矸石集料混凝土的细微观结构与材料力学性能之间的内在联系，提出了混凝土制备中煤矸石集料的选用原则和煤矸石集料混凝土的设计方法。采用混凝土力学试验方法，研究了C15~C30四个强度等级的两种煤矸石集料混凝土4个龄期的混凝土立方体抗压强度、轴心抗压强度和劈裂抗拉强度等基本力学性能的发展规律。通过回归分析，建立了轴心抗压强度、劈裂抗拉强度与立方体抗压强度之间的关系式；通过试验获取了自燃和非自燃煤矸石集料混凝土的单轴受压应力-应变全曲线，建立了峰值应变、弹性模量、泊松比与峰值应力之间的关系式，提出了煤矸石集料混凝土的单轴受压本构模型，试块数量共计312个。采用光纤光栅传感技术，研究了煤矸石集料混凝土的早期收缩和开裂性能，分析了煤矸石集料混凝土的塑性收缩、自身收缩、化学减缩及干燥收缩性能，得出了活性和非活性煤矸石集料的掺入将加剧混凝土的早期收缩，其中煤矸石的吸水性、煤矸石掺入引起的泌水回吸、自燃煤矸石活性反应以及自燃煤矸石中碱金属元素引起的化学反应等是引起混凝土早期收缩与开裂的主要原因。基于煤矸石力学性能的多因素化和影响性能的多元化，选取了徐州7个煤矿12个煤矸石试样，通过灰色关联分析，得到了影响煤矸石集料混凝土抗压强度的影响因素，其由大到小依次为煤矸石的岩石强度、针片状含量、吸水率、颗粒级配的分形维数、堆积密度和矸石含水率。根据煤矸石集料混凝土抗压强度因素之间大小差异，建立了基于灰色理论的煤矸石集料品质评估模型，提出了煤矸石集料质量的评估体系和预测方法。更多还原

【Abstract】 Coal gangue is currently one of the largest industrial wastes in annual emissionsand the cumulative stocks in China. Therefore, utilizing coal gangue as buildingmaterials is an effective way to realize renewable use of it.The dissertation selectedcoal gangue as concrete aggregates,by using the theoretical mathematical model,physical-mechanical experiments and optical fiber sensing technology and so on. Theinfluences on the micro-structure and physical-mechanical performance of concretewith coal gangue as aggregate incorporation were studied. And the fundamentalmechanical and early shrinkage performance were analysis; evaluation model of coalgangue aggregate’s quality was obtained. The research conclusions would offertheoretical basis for further application and promotion of coal gangue concrete.Combined with phase analytical method and materials micro-morphology, theinfluence of coal gangue aggregate activity on the micro-structure of concrete wasstudied.The phase analysis indicated that new substances such as gismondine andandradite were generated after secondary hydrated reaction of active coal gangueaggregate. In the microstructure analysis, the compact structure can’t form afterhydration due to that hydration products cross-linked each other to form large poremesh skeleton system which filled in the microscopic pores and fractures. So theactivity of coal gangue couldn’t improve the microstructure characteristics of cementpaste. The influence of the macroscopic mechanical properties were that hydratedreaction can promot its early compressive strength, but had little effect on the latercompressive strength. The strength coordination between coal gangue and cementmatrix was also a key factor for macro-properties development of cement mortarBy using XRD, SEM, EDXA, MIP, the interface microstructure, chemicalelements distribution、migration and enrichment in ITZ, micro-hardness analysis andpore structure were studied. Based on the theory of material pore science andmicroscopic structure of concrete, the physical and chemical mechanism among thecoal gangue aggregate and the cement paste was revealed and the ITZ’s structuremodel of coal gangue aggregate concrete was built.The mechanical performance of288test blocks were performed by material testwith considering the influence of coal gangue types, grain composition, pretreatment,curing condition and two kinds of W/C. Combined with the development of itsmechanical performance, the inner connection between the microstructure and macro -mechanical performance was established. Besides the selection principle of coalgangue aggregate and the design method of coal gangue aggregate concreteWith concrete materials testings, the fundamental mechanical performances oftwo kinds of coal gangue aggregate concrete were experimented. With regressinganalysis, the empirical equations describing the relationship between axialcompressive strength, plitting strength and cubic compressive strength were obtained;and coal gangue aggregate concrete’s complete curves of stress-strain were gained byexperiments. The strength and deformation index’s relationship as: peak strain,ultimate strain, elastic modulus and poisson ratio which were reflected in thestress-strain curves had built through the relationship with ordinary concrete, and theconstitutive model of coal gangue aggregate concrete was established. The specimenswere312blocks totally.By using the fiber grating sensing technology, coal gangue aggregate concrete’searly shrinkage performance were examined which mainly include concrete’s plasticshrinkage, autogenously shrinkage, chemical condensation and dry shrinkage. And thetesting results showed that active and inactive coal gangue aggregate incorporationwill exacerbate early shrinkage of concrete. The primary causes include that gangue‘swater-absorbing, bleeding resorption, activity and chemical reaction.Based on multiple factors affected the mechanical performance and theproperties diversified of coal gangue,12kinds of coal gangue specimens wereselected from7different coal mine in Xuzhou. Based on the gray correlation analysis,the influencing factors on concrete mechanical performance were obtained and theireffect from large to small in turn is rock strength, the contents of needle-like particles,water absorption, fractal dimension of grain grading, bulk density and moisturecontent. The comprehensive evaluation model of coal gangue aggregate quality basedon GM (1,4) was built, and assessment and prediction of coal gangue aggregatequality were proposed.更多还原