本文選題：混凝土 + 工作性��； 參考：《東南大學(xué)》2015年碩士論文

【摘要】：良好工作性的新拌混凝土對(duì)保障硬化后性能十分重要,建立合理、有效的工作性評(píng)估方法有益于保證工程質(zhì)量。本文以坍落度140mm到220mm的C50大流動(dòng)性混凝土為例,研究了工作性的差異對(duì)力學(xué)性能、耐久性能勻質(zhì)性的影響,在此基礎(chǔ)上評(píng)估混凝土的工作性；并嘗試將圖像處理方法引入到工作性評(píng)估中。同時(shí)研究了不同因素對(duì)漿體流動(dòng)性、粘聚性、保水性的影響規(guī)律,從而達(dá)到有效控制混凝土工作性的目的。研究了水膠比、礦物摻合料、減水劑對(duì)水泥凈漿、砂漿流動(dòng)性、粘聚性、保水性的影響規(guī)律。試驗(yàn)結(jié)果表明：水膠比、礦粉、減水劑摻量的增加對(duì)漿體流動(dòng)性的改善效果較為明顯,但會(huì)帶來粘聚性、保水性的變差,大摻量礦粉的使用會(huì)降低漿體粘聚性、保水性；而Ⅰ級(jí)粉煤灰在增大流動(dòng)性的同時(shí)能夠保持很好的粘聚性、保水性,能夠彌補(bǔ)因增大減水劑和礦粉摻量帶來的工作性負(fù)面影響。砂漿和水泥凈漿在不同因素影響下工作性發(fā)展規(guī)律相近,尤其是二者粘聚性相關(guān)性較大,表明通過漿體粘聚性影響因素控制混凝土上作性的可行性并在工程中得到了應(yīng)用。闡明了工作性與硬化混凝土力學(xué)性能、耐久性能的勻質(zhì)性關(guān)系。隨著混凝土工作性的變差,不同部位混凝土的抗壓強(qiáng)度、動(dòng)彈性模量、氯離子遷移系數(shù)、氣體滲透系數(shù)、干縮變形的離差也越來越大,即混凝土的勻質(zhì)性越差。骨料離析率、泌水率等工作性指標(biāo)與混凝土勻質(zhì)性存在關(guān)聯(lián),并以此建立了基于混凝土勻質(zhì)性的工作性評(píng)估方法,為現(xiàn)場(chǎng)工作性的量化評(píng)估提供依據(jù)。探索了圖像處理方法在漿體工作性評(píng)估中的應(yīng)用。通過圖像分析獲取了漿體擴(kuò)展面積隨時(shí)間實(shí)時(shí)變化曲線并以計(jì)算擴(kuò)展度的形式來表現(xiàn),極大地提高了流動(dòng)性測(cè)量的精度,并通過漿體流動(dòng)截止時(shí)間很好地表征了漿體的粘聚性,同時(shí)獲取了漿體表面氣泡實(shí)時(shí)變化規(guī)律以及最終擴(kuò)展形態(tài)。為現(xiàn)場(chǎng)混凝土工作性的快速評(píng)估提供了理論支撐和可行性驗(yàn)證。通過微觀分析手段,檢測(cè)不同工作性混凝土在孔結(jié)構(gòu)、水化產(chǎn)物、微觀形貌的差異,結(jié)果證實(shí)勻質(zhì)性的差異在微觀尺度上也得到了反映。
[Abstract]:The good workability of fresh concrete is very important to guarantee the performance after hardening. Establishing a reasonable and effective evaluation method of workability is beneficial to guarantee the engineering quality. Taking C50 fluidity concrete with slump 140mm to 220mm as an example, the influence of workability difference on mechanical properties and durability homogeneity is studied, and the workability of concrete is evaluated. And try to introduce the image processing method into the evaluation of workability. At the same time, the effects of different factors on slurry fluidity, agglomeration and water retention are studied, so as to effectively control the workability of concrete. The effects of water / binder ratio, mineral admixture and water reducing agent on cement paste, mortar fluidity, agglomeration and water retention were studied. The results show that: the increase of water / binder ratio, ore powder and water reducing agent content can improve the slurry fluidity obviously, but it will bring about the agglomeration, the water retention property becomes worse, and the use of the large amount of mineral powder will reduce the slurry agglomeration and water retention; The first grade fly ash can keep good cohesion and water retention while increasing the fluidity, which can make up for the negative effect of increasing the amount of water reducer and mineral powder. The development law of workability of mortar and cement mortar is similar under the influence of different factors, especially the relativity of their cohesion, which indicates that it is feasible to control the performance of concrete by influencing factors of mortar cohesion and has been applied in engineering. The homogeneity relationship between workability and mechanical properties and durability of hardened concrete is expounded. As the workability of concrete becomes worse, the difference of compressive strength, dynamic elastic modulus, chloride ion transfer coefficient, gas permeability coefficient and dry shrinkage deformation of concrete is increasing, that is to say, the homogeneity of concrete is worse. The workability indexes such as aggregate segregation rate, bleeding rate and so on are related to the homogeneity of concrete. Based on this, a workability evaluation method based on concrete homogeneity is established, which provides the basis for the quantitative evaluation of on-site workability. The application of image processing in the evaluation of slurry workability is explored. The real time curve of slurry expansion area is obtained by image analysis and expressed in the form of calculating expansion degree, which greatly improves the accuracy of flow measurement, and indicates the cohesiveness of slurry through the cut-off time of slurry flow. At the same time, the real-time change rule and the final expansion morphology of the bubbles on the slurry surface were obtained. It provides theoretical support and feasibility verification for quick evaluation of site concrete workability. The difference of pore structure, hydration product and microstructure of different working concrete was detected by means of microscopic analysis. The results show that the difference of homogeneity is also reflected in microscopic scale.
【學(xué)位授予單位】：東南大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：TU528

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