本文選題：干旱風沙 + 混凝土��； 參考：《中國鐵道科學研究院》2015年博士論文

【摘要】：針對西部地區(qū)大風干旱大溫差的環(huán)境條件造成混凝土養(yǎng)護困難且極易開裂的現(xiàn)狀。采用理論分析、室內(nèi)微觀和宏觀性能測試以及現(xiàn)場工程驗證相結合的研究方法,研發(fā)出與干旱風沙地區(qū)環(huán)境相適應的混凝土抗裂材料,提出了混凝土裂縫控制的成套技術,為促進西部地區(qū)混凝土抗裂技術的發(fā)展和應用提供了重要的參考。所開展的工作和取得的成果有：首先,調(diào)研現(xiàn)場環(huán)境條件和混凝土結構開裂特征,分析干旱風沙地區(qū)混凝土裂紋發(fā)生規(guī)律及機理,明確水分蒸發(fā)快和收縮大是材料層面造成混凝土開裂的主要因素。從工程實際對混凝土技術性和經(jīng)濟性需求角度出發(fā),提出內(nèi)部補償濕度和外部減少蒸發(fā)的混凝土裂縫控制技術思路。其次,采用不同的合成工藝制備出不同種類的高吸水樹脂(SAP),通過在不同介質(zhì)、不同離子強度溶液中的吸水倍率、吸水速率試驗以及對混凝土拌合物性能、變形性能的影響,優(yōu)選出丙烯酰胺類高吸水樹脂作為濕度調(diào)控組分,并確定其粒徑大小為0.12mm～ 0.25mm。優(yōu)選出保水組分和減縮組分與濕度調(diào)控組分匹配化設計,開發(fā)出具有12h減縮率為56%、28d減縮率為25%,顯著提高混凝土的抗裂性能且不降低混凝土強度和耐久性的內(nèi)養(yǎng)護材料。再次,針對干旱風沙地區(qū)常規(guī)的澆水覆蓋保濕養(yǎng)護較難實現(xiàn),且不能解決混凝土的早期水份散失問題,系統(tǒng)研究了成膜組分、無機增強組分和改性組分對混凝土養(yǎng)護劑保水性能的影響規(guī)律,結合干旱風沙地區(qū)環(huán)境特征,開發(fā)出性能良好,有效保水率達85%以上外養(yǎng)護劑,提出了適合于現(xiàn)場應用的養(yǎng)護劑性能評價方法及混凝土養(yǎng)護效果優(yōu)劣的評價指標。然后,在研究輔助膠凝材料及配合比配制參數(shù)對混凝土工作性能、力學性能、體積穩(wěn)定性能和耐久性能的影響規(guī)律的基礎上,提出了遵循“三低一高”(低膠材用量、低用水量、低坍落度、高含氣量)原則,并通過補償化學收縮理論計算及試配驗證摻入適量的SAP引入內(nèi)養(yǎng)護水的高抗裂內(nèi)養(yǎng)護混凝土配制技術。采用XRD、TG、孔結構分析與核磁共振測試技術分析了水泥漿體中各相水的分布,研究了內(nèi)養(yǎng)護水對體系毛細負壓、水化程度及孔結構的影響規(guī)律,提出了吸蓄水SAP在水泥漿體水化過程中的作用模型,揭示了內(nèi)養(yǎng)護作用機制。最后,系統(tǒng)研究了高抗裂內(nèi)養(yǎng)護混凝土的攪拌、運輸、澆注、振搗和養(yǎng)護工藝等工程應用的關鍵技術,將研發(fā)的具有減縮抗裂作用的內(nèi)養(yǎng)護材料和具有高效保水作用的外養(yǎng)護劑應用于蘭新鐵路第二雙線混凝土工程,實現(xiàn)了干旱風沙地區(qū)混凝土結構裂縫寬度滿足規(guī)范驗收要求的目的,彌補了現(xiàn)有混凝土抗裂技術與環(huán)境適應性差、對養(yǎng)護依賴性強和作用對象單一等不足。
[Abstract]:In view of the environmental condition of high temperature difference caused by high wind and drought in the western region, the maintenance of concrete is difficult and it is easy to crack. By means of theoretical analysis, indoor microscopic and macroscopic performance testing and field engineering verification, a concrete crack resistant material adapted to the environment of arid wind-sand area was developed, and a complete set of concrete crack control technology was put forward. It provides an important reference for the development and application of concrete crack resistance technology in the western region. The main works and achievements are as follows: first of all, by investigating the environmental conditions and cracking characteristics of concrete structures, we analyze the occurrence law and mechanism of concrete cracks in arid wind-sand areas. It is clear that fast moisture evaporation and large shrinkage are the main factors causing concrete cracking. From the point of view of the technical and economic requirements of concrete in engineering practice, this paper puts forward the technical thinking of concrete crack control with internal humidity compensation and external evaporation reduction. Secondly, different kinds of superabsorbent resin (SAP) were prepared by different synthetic processes. The effects of water absorption ratio, water absorption rate test and the effect on concrete mixing properties and deformation properties in different medium and different ionic strength solution were studied. Acrylamide superabsorbent resin was selected as humidity control component and its particle size was determined to be 0.12mm ~ 0.25mm. An internal curing material with 12h shrinkage reduction rate of 56 and 28 days is developed, which can significantly improve the crack resistance of concrete and does not reduce the strength and durability of concrete. Thirdly, in view of the difficulty of water mulching and moisturizing maintenance in arid wind-sand area and the failure to solve the problem of water loss in early stage of concrete, the film-forming components are studied systematically. The effect of inorganic reinforcement and modified components on the water retention performance of concrete curing agents was studied. Combined with the environmental characteristics of arid wind-sand areas, a good performance was developed, and the effective water retention rate was more than 85%. The performance evaluation method of curing agent suitable for field application and the evaluation index of curing effect of concrete are put forward. Then, on the basis of studying the influence of auxiliary cementing materials and mixing ratio parameters on the performance, mechanical properties, volume stability and durability of concrete, it is proposed to follow the principle of "three low and one high" (low rubber content). The principle of low water consumption, low slump and high gas content is used. The compounding technology of high crack curing concrete with proper amount of SAP is verified by the calculation of compensatory chemical shrinkage theory and the trial match. The distribution of water in different phases of cement paste was analyzed by means of XRDX TG, pore structure analysis and nuclear magnetic resonance (NMR) technique. The effects of internal curing water on the capillary negative pressure, hydration degree and pore structure of the cement paste were studied. The action model of SAP in hydration of cement paste is proposed, and the mechanism of internal curing is revealed. Finally, the key technologies of mixing, transporting, pouring, vibrating and curing technology of high crack resistant inner curing concrete are systematically studied. The developed internal curing materials with shrinkage and crack resistance and external curing agents with high efficiency and water retention were applied to the second double-track concrete project of Lanxin Railway. The crack width of concrete structure in arid wind-sand area can meet the requirements of code acceptance, which makes up for the shortcomings of existing concrete crack resistance technology and environmental adaptability, strong dependence on conservation and single object of action and so on.
【學位授予單位】：中國鐵道科學研究院
【學位級別】：博士
【學位授予年份】：2015
【分類號】：TU755.7

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