發(fā)布時間：2018-12-20 07:16

【摘要】：隨著現(xiàn)代建筑向著高層、大跨徑方向的發(fā)展，人們對混凝土的要求也越來越高，普通高強混凝土因其自重大問題的存在，，在大型工程使用中受到越來越多的約束。而近年來人造輕骨料特別是高強陶粒的快速發(fā)展為解決這個問題提供了一個契機。高強陶粒具有輕質、高強、低吸水率的特點，將其用于混凝土的制備能在保證相同強度等級的情況下降低自重20%～30%。為此本文針對LC50輕骨料混凝土的配合比設計及各方面性能展開了系統(tǒng)研究，獲得以下結論： （1）選用湖北宜昌寶珠陶粒有限公司生產的高強頁巖陶粒作為粗骨料，通過配合比設計確定了一組初始配合比，并通過試驗研究了水灰比、砂率與骨料平均粒徑對LC50輕骨料混凝土坍落度、表觀密度以及強度等性能的影響規(guī)律，對初始配合比進行優(yōu)選，成功配制出強度等級為LC50的輕骨料混凝土。 （2）在配制出LC50輕骨料混凝土的基礎上研究了預濕時間、顆粒類型、粒徑、粉煤灰、砂的細度模數(shù)、細骨料類型等對拌合物性能的影響規(guī)律，通過試驗研究，確定了對LC50輕骨料混凝土拌合物性能影響的主要因素，為配制具有良好工作性能LC50輕骨料混凝土提供了一定的理論基礎與技術支持。 （3）對LC50輕骨料混凝土力學性能與耐久性能進行了研究，試驗結果表明，粉煤灰的摻入能夠提升LC50輕骨料混凝土的后期強度，而預濕處理會降低混凝土早期強度，但是有益于后期強度的發(fā)展；粉煤灰和鋼渣粉的摻入降低了輕骨料混凝土的抗碳化性能；而超細粉煤灰和磨細礦粉的摻入，卻能在一定程度上提升LC50輕骨料混凝土抗碳化性能；LC50輕骨料混凝土在碳化作用下干縮變形會顯著增長，但利用礦物摻合料等量取代水泥摻入，能較好的抑制其碳化收縮率；同時良好的預濕工藝對也輕骨料混凝土的減縮防裂是較為有利的。 （4）對LC50輕骨料混凝土在荷載條件下與硫酸鹽侵蝕的非荷載條件下的內部微觀裂紋擴展規(guī)律進行了研究，引入工業(yè)計算機斷層掃描系統(tǒng)檢測了不同類型LC50輕骨料混凝土的內部裂紋狀況，以此分析了輕骨料混凝土的損壞機理，發(fā)現(xiàn)了LC50輕骨料混凝土破壞過程中裂紋擴展規(guī)律與普通混凝土的諸多不同，為解釋LC50輕骨料混凝土實際應用過程的損害機制提供了理論依據(jù)。
[Abstract]:With the development of modern building towards high-rise and long-span direction, the demand for concrete is becoming higher and higher. Because of its serious problems, ordinary high-strength concrete is subjected to more and more constraints in the use of large-scale projects. In recent years, the rapid development of artificial lightweight aggregate, especially high-strength ceramsite, provides an opportunity to solve this problem. High strength ceramsite has the characteristics of light weight, high strength and low water absorption. Its application in the preparation of concrete can reduce the weight of 20% and 30% under the condition of the same strength grade. In this paper, the proportion design and performance of LC50 lightweight aggregate concrete are systematically studied, and the following conclusions are obtained: (1) the high strength shale ceramsite produced by Yichang Baozhu Ceramsite Co., Ltd., Hubei Province, is selected as coarse aggregate. A group of initial mix ratios were determined by mix ratio design, and the effects of water-cement ratio, sand ratio and average particle size of aggregate on slump, apparent density and strength of LC50 lightweight aggregate concrete were studied. The lightweight aggregate concrete with LC50 strength grade was successfully prepared by selecting the initial mix ratio. (2) based on the preparation of LC50 lightweight aggregate concrete, the effects of pre-wetting time, particle type, particle size, fly ash, fineness modulus of sand and fine aggregate type on the properties of the mixture were studied. The main factors affecting the physical properties of LC50 lightweight aggregate concrete are determined, which provide a theoretical basis and technical support for the preparation of LC50 lightweight aggregate concrete with good working performance. (3) the mechanical properties and durability of LC50 lightweight aggregate concrete are studied. The experimental results show that the addition of fly ash can enhance the later strength of LC50 lightweight aggregate concrete, while pre-wetting treatment can reduce the early strength of concrete. But it is beneficial to the development of the later intensity; The addition of fly ash and steel slag powder reduces the carbonation resistance of lightweight aggregate concrete, while the addition of ultrafine fly ash and fine grinding powder can improve the carbonation resistance of LC50 lightweight aggregate concrete to some extent. The dry shrinkage deformation of LC50 lightweight aggregate concrete will increase significantly under carbonization, but the carbonation shrinkage of LC50 lightweight aggregate concrete can be inhibited by using mineral admixture to replace cement in the same amount. At the same time, a good pre-wetting process is beneficial to reduce shrinkage and crack of lightweight aggregate concrete. (4) the microcosmic crack propagation law of LC50 lightweight aggregate concrete under load and sulfate erosion is studied. The internal cracks of different types of LC50 lightweight aggregate concrete were detected by using the industrial computer tomography system, and the damage mechanism of the lightweight aggregate concrete was analyzed. It is found that the crack propagation law of LC50 lightweight aggregate concrete is different from that of ordinary concrete, which provides a theoretical basis for explaining the damage mechanism of LC50 lightweight aggregate concrete in practical application.
【學位授予單位】：長沙理工大學
【學位級別】：碩士
【學位授予年份】：2013
【分類號】：TU528.2

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