高强页岩陶粒轻骨料混凝土拌合物性能及体积变形

发布时间：2018-03-22 02:32

本文选题：轻骨料混凝土　切入点：工作性　出处：《长沙理工大学》2015年硕士论文　论文类型：学位论文

【摘要】：随着现代桥梁工程向着大跨径方向的发展,普通混凝土因其自重大成为限制桥梁工程的发展的“瓶颈”。而近年来以工业废渣、城市废弃物等为主要原料生产的高强陶粒发展日趋成熟,人们可大量利用绿色轻骨料替代天然骨料配制轻骨料混凝土,轻骨料混凝土因其高强轻质高耐久性的特点弥补了普通混凝土在大跨径桥梁中的局限性。本文针对桥梁工程轻骨料混凝土的工作性和体积变形进行系统研究,主要结论如下:(1)选用高强页岩陶粒作为粗骨料,根据松散体积法确定确定轻骨料混凝土初始配合比,采用单因素变量法分别研究了配合比中各因素对轻骨料混凝土工作性和力学强度的影响,进而优化初始配合比。(2)基于轻骨料混凝土的配合比研究了骨料预湿状态、骨料颗粒类型和级配、砂的细度模数、不同细度粉煤灰等对拌合物性能的影响规律,确定了影响轻骨料混凝土拌合物性能的主要因素。(3)对轻骨料混凝土力学强度和体积变形进行了研究。试验结果表明,粉煤灰替代水泥制备轻骨料混凝土的早期收缩变形得到明显抑制,粉煤灰掺量越大,抑制效果越明显;粉煤灰细度越高,减缩效果越明显;随着水胶比的降低,粉煤灰轻骨料混凝土的体积变形较为明显;通过改变页岩陶粒预湿状态可显著改善混凝土早期体积变形;引入工业计算机断层扫描系统检测了轻骨料混凝土的内部裂纹状况,粉煤灰轻骨料混凝土在加载条件下发生破坏,裂纹扩展路径与受力方向保持一致,裂纹产生后并未沿浆骨界面过渡区开裂,而是直接纵穿陶粒骨料。(4)基于椭圆环法和平板法试验,研究了不同比例钢纤维的粉煤灰轻骨料混凝土的早期体积变形,结果表明,随着钢纤维掺量的增加,减缩效果越来越显著;掺入钢纤维的粉煤灰轻骨料混凝土的抗压强度和劈裂抗拉强度均得到一定程度的提高,且随钢纤维掺量的增加呈上升趋势;掺钢纤维的轻骨料混凝土的破坏形式发生变化,破坏后试件无明显角料剥落。
[Abstract]:With the development of modern bridge engineering towards the direction of long span, ordinary concrete has become the "bottleneck" that restricts the development of bridge engineering because of its importance. The development of high-strength ceramsite which is the main raw material of city waste is becoming more and more mature. People can use green lightweight aggregate instead of natural aggregate to prepare lightweight aggregate concrete. Lightweight aggregate concrete has made up for the limitation of ordinary concrete in long span bridges because of its high strength, light weight and durability. This paper makes a systematic study on the workability and volume deformation of lightweight aggregate concrete in bridge engineering. The main conclusions are as follows: (1) High strength shale ceramsite is chosen as coarse aggregate, and the initial mix ratio of lightweight aggregate concrete is determined according to loose volume method. The influence of various factors in mix ratio on the workability and mechanical strength of lightweight aggregate concrete was studied by single factor variable method, and then the initial mix ratio was optimized. (2) based on the mix ratio of lightweight aggregate concrete, the pre-wet state of aggregate was studied. The effects of particle type and gradation of aggregate, modulus of fineness of sand and fly ash of different fineness on the properties of the mixture, The main factors affecting the performance of lightweight aggregate concrete are determined. The mechanical strength and volume deformation of lightweight aggregate concrete are studied. The early shrinkage deformation of lightweight aggregate concrete prepared by fly ash instead of cement is obviously inhibited. The higher the content of fly ash is, the more obvious the inhibition effect is; the higher the fineness of fly ash is, the more obvious the shrinkage reduction effect is; with the decrease of water-binder ratio, The volume deformation of fly ash lightweight aggregate concrete is obvious, the early volume deformation of concrete can be significantly improved by changing the pre-wetting state of shale ceramsite, and the internal crack condition of lightweight aggregate concrete is detected by introducing the industrial computer tomography system. The fly ash lightweight aggregate concrete is destroyed under the loading condition, and the crack propagation path is consistent with the stress direction, and the crack does not crack along the transition zone of the interface between the slurry and the bone. The early volume deformation of fly ash lightweight aggregate concrete with different proportion of steel fiber is studied based on elliptical ring method and plate method. The results show that the volume deformation of fly ash lightweight aggregate concrete with different proportion of steel fiber increases with the increase of steel fiber content. The compression strength and splitting tensile strength of fly ash lightweight aggregate concrete mixed with steel fiber have been improved to some extent, and with the increase of steel fiber content, the compressive strength and splitting tensile strength of fly ash lightweight aggregate concrete have been increased. The failure form of lightweight aggregate concrete mixed with steel fiber has changed, and there is no obvious peeling off of the specimen after failure.
【学位授予单位】：长沙理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TU528

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