【摘要】：隨著建筑業(yè)高速發(fā)展,建筑廢棄物也急劇增加,將其中的廢棄混凝土回收處理后作為再生骨料不僅能降低成本、解決城市建筑廢棄物的堆放、占地和環(huán)境污染等問題,而且能實現(xiàn)混凝土工業(yè)的物質(zhì)循環(huán)利用,保證建筑工業(yè)的可持續(xù)發(fā)展。但是,再生骨料相對于天然骨料而言,顆粒棱角多,表面粗糙,再加上廢棄混凝土塊在破碎過程中產(chǎn)生大量微裂縫,使得再生混凝土與天然混凝土的性能存在差異。因此,本文以試驗研究為主,對再生混凝土的力學性能和微觀形貌進行研究,開展的工作及得出的結(jié)論如下:1.保持水灰比0.55不變,改變再生骨料取代率來研究再生混凝土的工作性能和力學性能。再生骨料取代率分別為0、20%、30%、40%、50%、60%、70%、80%、100%。試驗結(jié)果表明:隨著再生骨料取代率增大,新拌混凝土流動性變差,粘聚性和保水性增強;當再生骨料取代率分別為20%、40%、50%、60%、70%、80%、100%時,再生混凝土的抗壓強度比普通混凝土低;但當再生骨料取代率為30%時,再生混凝土的抗壓強度較普通混凝土反而有所提高,建議再生骨料取代率控制在30%左右比較合理。2.在再生骨料取代率為100%的基礎(chǔ)上,設計了三種水灰比,水灰比分別為0.5、0.55、0.6,對于每一種水灰比采用粉煤灰等量取代水泥10%、20%、30%來研究粉煤灰對再生混凝土工作性能和力學性能的影響。試驗結(jié)果表明:再生混凝土的坍落度隨著粉煤灰摻量的增加而增加,流動性增強,但混凝土粘聚性和保水性基本保持不變;再生混凝土抗壓強度隨粉煤灰摻量的增加而減小,當粉煤灰摻量為20%時,再生混凝土抗壓強度降低最少。3.采用掃描電鏡對再生混凝土微觀形貌進行了研究。試驗結(jié)果表明:在再生混凝土中摻入粉煤灰使水泥水化產(chǎn)物中的Ca(OH)2晶體顆粒細化,密實性得到提高;隨著水灰比的減小,齡期的增加,水泥石結(jié)構(gòu)孔隙減少,界面過渡區(qū)更加密實和均勻。
[Abstract]:With the rapid development of the construction industry, the construction waste is also increasing rapidly. Using the waste concrete as recycled aggregate can not only reduce the cost, but also solve the problems such as stacking of urban construction waste, occupation of land and environmental pollution, etc. Moreover, it can realize the material recycling of concrete industry and ensure the sustainable development of construction industry. However, compared with natural aggregate, recycled aggregate has many edges, rough surface and a large number of micro-cracks in the process of crushing of waste concrete, which makes the performance of recycled concrete and natural concrete different. Therefore, the mechanical properties and microscopic morphology of recycled concrete are studied in this paper, and the results are as follows: 1. The working and mechanical properties of recycled concrete were studied by changing the replacement ratio of recycled aggregate and keeping the water-cement ratio at 0.55. The replacement rate of regenerated aggregate is 0, 20, 30, 40, 50, 50, 60, 70, and 80, 80, 100. The experimental results show that with the increase of recycled aggregate substitution rate, the flowability of fresh concrete becomes worse, the cohesion and water retention increase, and the compressive strength of recycled concrete is lower than that of ordinary concrete when the replacement ratio of recycled aggregate is 20, 404050 and 50, respectively. But when the replacement ratio of recycled aggregate is 30, the compressive strength of recycled concrete is higher than that of ordinary concrete. It is suggested that the replacement rate of recycled aggregate should be controlled at 30% or so. On the basis of 100% replacement rate of recycled aggregate, three kinds of water-cement ratio are designed, the water-cement ratio is 0.550.65%, respectively. For each kind of water-cement ratio, fly ash is used to replace the cement with the equal amount of fly ash to study the influence of fly ash on the working performance and mechanical properties of recycled concrete. The test results show that the slump of recycled concrete increases with the increase of fly ash content, and the fluidity increases, but the cohesion and water retention of recycled concrete remain unchanged, and the compressive strength of recycled concrete decreases with the increase of fly ash content. When the content of fly ash is 20%, the compressive strength of recycled concrete decreases by a minimum of. 3. 3. The microstructure of recycled concrete was studied by scanning electron microscope (SEM). The experimental results show that adding fly ash into recycled concrete can refine the Ca (OH) _ 2 crystal particles and improve the compactness of cement hydration products, and with the decrease of water-cement ratio and the increase of age, the pore size of cement stone structure decreases. The transition zone of the interface is more dense and uniform.
【學位授予單位】：浙江工業(yè)大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：TU528

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相關(guān)期刊論文 前1條

1 肖建莊;張潔;;上海市廢棄混凝土來源與回收前景[J];粉煤灰;2006年03期

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本文編號：2237338