碳纳米管水泥砂浆的力学、物理及耐久性研究

发布时间：2018-04-02 10:37

本文选题：碳纳米管　切入点：水泥砂浆　出处：《哈尔滨工业大学》2014年硕士论文

【摘要】：碳纳米管具有良好的力学、导电和导热等特性，也因为其优良的微观纤维增强增韧和纳米填充特性，使得碳纳米管在改善水泥基复合材料的力学、电学和耐久性等方面具有良好的工程应用前景。鉴于目前碳纳米管水泥基复合材料的研究领域主要集中在碳纳米管水泥净浆的力学和电学方向，而水泥砂浆更接近真实的工程要求，所以有必要对碳纳米管改善水泥砂浆性能进行全面的研究。本文以实际工程为导向，从水泥基复合材料的早期发展和长期耐久性角度考虑，通过宏观实验和微观实验相结合的方法，对碳纳米管水泥砂浆的力学、物理及耐久性方面进行了比较系统的研究，同时对碳纳米管改善水泥砂浆的改性机理进行了初步的探索。主要包括以下的研究工作：在碳纳米管改善水泥砂浆力学性能方面，通过3d、7d和28d不同龄期下的抗压强度实验与28d龄期下的抗折强度实验，对比研究了在相同减水剂用量和相同流动度两种情况下，0.1%、0.3%和0.5%不同掺量的碳纳米管水泥砂浆与普通水泥砂浆的力学性能，并结合SEM形貌分析初步探讨了碳纳米管改善水泥砂浆力学强度的作用机制。研究结果表明：碳纳米管的掺入可以有效改善碳纳米管水泥砂浆的抗压强度和抗折强度，并且改善效果主要集中在早期阶段；0.3%掺量的碳纳米管水泥砂浆在综合力学性能上改善效果最优；碳纳米管对水泥砂浆的宏观力学性能的改善主要归因于碳纳米管的桥联和微填充作用。在碳纳米管改善水泥砂浆物理性能方面，利用XRD分析了水化反应物和生成物成分的相对变化，另外进行了流动度、水化热、水分散失量以及不同养护条件下力学强度和干燥养护下的早期收缩等试验，对比研究了碳纳米管水泥砂浆和普通水泥砂浆的流动性、水化发展过程、保水性和收缩性等物理性能。研究结果表明：碳纳米管的掺入可以降低水泥砂浆的流动度、加速水泥的水化；在干燥养护条件下碳纳米管水泥砂浆水分散失量更少，与标准养护条件相比，力学性能提高幅度更大；同时碳纳米管可以有效改善水泥砂浆的早期收缩。在碳纳米管改善水泥砂浆耐久性能方面，，通过干湿循环抗硫酸盐侵蚀实验和慢冻法抗冻实验，分别测量试件恶劣环境下和标准养护下30d，60d和90d的抗压强度，对比研究了碳纳米管水泥砂浆和普通水泥砂浆的耐久性能，并分析了其抗劣化机理。研究结果表明：在干湿循环和冻融循环的实验环境下，碳纳米管水泥砂浆的抗压强度损失率更低；与普通砂浆相比，碳纳米管水泥砂浆抗硫酸盐侵蚀和抗冻能力的提高，归因于碳纳米管对水泥砂浆在孔结构改善、阻裂两个方面的协同作用。
[Abstract]:The carbon nanotubes have good mechanical , electrical and thermal conductivity properties , and the carbon nanotubes have good engineering application prospects in improving the mechanical , electrical and durability properties of the cement - based composite materials . In view of the present research fields of the carbon nano - tube cement - based composite materials , the paper studies the mechanical , physical and durability aspects of the carbon nano - tube cement mortar .

The mechanical properties of carbon nano - tube cement mortar and ordinary cement mortar under the same water reducing agent dosage and the same fluidity were studied . The mechanical properties of the carbon nano - tube cement mortar and ordinary cement mortar were studied by means of three - dimensional , 7 - day and 28 - day compressive strength experiments . The mechanism of the effect of the carbon nanotubes on the mechanical strength of cement mortar was discussed .
0 . 3 % of carbon nanotube cement mortar has the best effect on comprehensive mechanical properties ;
The improvement of the macroscopic mechanical properties of the carbon nanotubes to the cement mortar is mainly attributed to the bridging and microfilling of the carbon nanotubes .

In the aspect of improving the physical properties of cement mortar by carbon nanotubes , the relative changes of hydration reactant and product components were analyzed by XRD . The properties of fluidity , hydration , water retention and shrinkage of cement mortar and common cement mortar were studied by XRD . The results showed that the incorporation of carbon nanotubes could reduce the fluidity of cement mortar and accelerate the hydration of cement mortar .
Under the condition of dry curing , the amount of water loss of the carbon nano - tube cement mortar is less , and the mechanical property is improved more when compared with the standard curing condition ;
meanwhile , the carbon nano tube can effectively improve the early shrinkage of the cement mortar .

In the aspect of improving the durability of cement mortar by using carbon nanotubes , the compressive strength of 30 days , 60 days and 90 days under harsh environment and standard curing was measured by dry and wet cyclic sulfate attack experiment and slow freezing method . The durability properties of carbon nanotube cement mortar and common cement mortar were studied . The results showed that the compressive strength loss rate of carbon nanotube cement mortar was lower in the experimental environment of dry and wet cycle and freeze - thaw cycle .
Compared with common mortar , the anti - sulfate corrosion and anti - freezing ability of the carbon nanotube cement mortar are improved , which is attributed to the synergistic effect of the carbon nanotubes on the improvement of the pore structure and the crack resistance .

【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TU578.1

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