本文選題：輕骨料混凝土　切入點：工作性　出處：《長沙理工大學》2015年碩士論文　論文類型：學位論文

【摘要】：隨著現(xiàn)代橋梁工程向著大跨徑方向的發(fā)展,普通混凝土因其自重大成為限制橋梁工程的發(fā)展的“瓶頸”。而近年來以工業(yè)廢渣、城市廢棄物等為主要原料生產(chǎn)的高強陶粒發(fā)展日趨成熟,人們可大量利用綠色輕骨料替代天然骨料配制輕骨料混凝土,輕骨料混凝土因其高強輕質高耐久性的特點彌補了普通混凝土在大跨徑橋梁中的局限性。本文針對橋梁工程輕骨料混凝土的工作性和體積變形進行系統(tǒng)研究,主要結論如下:(1)選用高強頁巖陶粒作為粗骨料,根據(jù)松散體積法確定確定輕骨料混凝土初始配合比,采用單因素變量法分別研究了配合比中各因素對輕骨料混凝土工作性和力學強度的影響,進而優(yōu)化初始配合比。(2)基于輕骨料混凝土的配合比研究了骨料預濕狀態(tài)、骨料顆粒類型和級配、砂的細度模數(shù)、不同細度粉煤灰等對拌合物性能的影響規(guī)律,確定了影響輕骨料混凝土拌合物性能的主要因素。(3)對輕骨料混凝土力學強度和體積變形進行了研究。試驗結果表明,粉煤灰替代水泥制備輕骨料混凝土的早期收縮變形得到明顯抑制,粉煤灰摻量越大,抑制效果越明顯;粉煤灰細度越高,減縮效果越明顯;隨著水膠比的降低,粉煤灰輕骨料混凝土的體積變形較為明顯;通過改變頁巖陶粒預濕狀態(tài)可顯著改善混凝土早期體積變形;引入工業(yè)計算機斷層掃描系統(tǒng)檢測了輕骨料混凝土的內(nèi)部裂紋狀況,粉煤灰輕骨料混凝土在加載條件下發(fā)生破壞,裂紋擴展路徑與受力方向保持一致,裂紋產(chǎn)生后并未沿漿骨界面過渡區(qū)開裂,而是直接縱穿陶粒骨料。(4)基于橢圓環(huán)法和平板法試驗,研究了不同比例鋼纖維的粉煤灰輕骨料混凝土的早期體積變形,結果表明,隨著鋼纖維摻量的增加,減縮效果越來越顯著;摻入鋼纖維的粉煤灰輕骨料混凝土的抗壓強度和劈裂抗拉強度均得到一定程度的提高,且隨鋼纖維摻量的增加呈上升趨勢;摻鋼纖維的輕骨料混凝土的破壞形式發(fā)生變化,破壞后試件無明顯角料剝落。
[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.
【學位授予單位】：長沙理工大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：TU528

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