组合养护和纳米材料对低水胶比再生骨料混凝土的性能影响

发布时间：2018-01-14 20:35

本文关键词：组合养护和纳米材料对低水胶比再生骨料混凝土的性能影响　出处：《北京交通大学》2017年硕士论文　论文类型：学位论文

【摘要】：再生骨料由于自身存在缺陷,所以由其制备的再生骨料混凝的力学性能和耐久性能都相对较差。根据本课题组之前的研究成果,低水胶比(0.18)条件下,组合养护可以有效提高浆体粘结强度,弥补粗骨料强度不足所带来的局限性,所以本论文采用此低水胶比(0.18)进行研究。主要采用以下三种方法对再生骨料混凝土的性能进行改性研究,具体包括:组合养护制度:拆模后90℃热水养护2天,再250℃干热养护3天;掺加纳米氧化硅(取代水泥质量的1%、2%、3%)并采取组合养护;掺加纳米氧化铝(取代水泥质量的1%、2%、3%)并采取组合养护。通过测定各组混凝土的力学性能和抗氯离子渗透性能,对比三种方法对再生骨料混凝土性能的改善效果。再生骨料与天然骨料的性能指标研究主要包括:骨料的级配性能、压碎指标、表观密度、坚固性指标和吸水性能。天然混凝土和再生骨料混凝土性能的研究主要包括:采用标准养护、组合养护、掺加纳米氧化硅并采用组合养护、掺加纳米氧化铝并采用组合养护的方式,制备九种类型混凝土,测试其抗压强度、劈裂抗拉强度、断裂能和抗氯离子渗透性能,通过试验结果,对比分析各种改性方法的改性效果。力学性能试验结果表明:采用组合养护可以显著提高再生骨料混凝土的力学性能,与标准养护相比,组合养护后再生骨料混凝土的抗压强度和劈裂抗拉强度分别提高了 26.8%、21.5%。掺加纳米氧化硅和纳米氧化铝并采用组合养护后,可使力学性能得到进一步的提升,且该提高效果会随纳米材料掺量的增加逐渐增大。与仅采用组合养护的再生骨料混凝土相比,组合养护并掺加3%纳米氧化铝的再生骨料混凝土的抗压强度和劈裂抗拉强度分别提高了 31.4%、18.2%;同时,相同掺量条件下,纳米氧化铝对再生骨料混凝土力学性能的改善效果优于纳米氧化硅。此外,低水胶比条件下,基体与骨料间界面粘结较强,导致无论天然混凝土、再生骨料混凝土还是采用三种改性方法制备的再生骨料混凝土,在断裂过程中均发生了骨料穿越破坏现象。抗氯离子渗透性能试验表明:采用组合养护或组合养护的同时掺加纳米材料的方法,均可以有效改善再生骨料混凝土的耐久性能。通过对比各种改性方法可以得出,组合养护的同时掺加适量的纳米材料后,再生混凝土的抗氯离子渗透性能已基本与天然混凝土持平,天然骨料混凝土的电通量为283.1 C,采用3%掺量的纳米氧化铝的电通量为315.7 C,二者的渗透等级均处于“非常低”水平。骨料的性能测试结果也反映出再生骨料与天然骨料性能之间的差距。与天然骨料相比,再生骨料的压碎指标、表观密度和坚固性指标较低,且颗粒级配较差、吸水率较高。
[Abstract]:The recycled aggregate because of its own defects, mechanical properties and durability of the recycled aggregate so by coagulation were relatively poor. According to the results from previous studies of our research group, low water binder ratio (0.18) under the condition of combined maintenance can effectively improve the bonding strength of slurry, compensate for limitations of coarse aggregate strength is insufficient bring, so this paper uses the low water binder ratio (0.18) is studied. Mainly use the following three methods on the performance of recycled aggregate concrete was modified, including: composite curing system: after stripping 90 DEG C hot water curing for 2 days, then 250 C dry curing 3 days; nano oxide silicon (replacing cement quality of 1%, 2%, 3%) and take the combination of maintenance; adding nano alumina (replacing cement quality of 1%, 2%, 3%) and take the combination of maintenance. By determination of the mechanical properties of each concrete and resistance to chloride ion permeability, comparison of the three party To improve the effect of performance of recycled aggregate concrete. The performance indexes of recycled aggregate and natural aggregate gradation index mainly includes: crushing performance, aggregate, apparent density, consistency index and water absorption performance. The study of natural concrete and recycled aggregate concrete performance mainly includes: the combination of standard maintenance, maintenance, adding nano the silicon oxide and the combination of curing, adding nano alumina and the curing method, preparation of nine types of concrete test, the compressive strength, splitting tensile strength, fracture energy and resistance to chloride ion penetration, through experimental results, comparative analysis of various modification methods of modification effect. The mechanical test results show that the combination of maintenance can significantly improve the mechanical properties of recycled aggregate concrete, compared with the standard maintenance, maintenance after the combination of recycled aggregate concrete compressive strength and splitting tensile strength The degree of increase were 26.8%, 21.5%. nano silicon oxide and nano alumina and the combination of the maintenance, the mechanical properties can be further improved, and the effect will be increased with the increase of nano material content increased gradually. Compared with the recycled aggregate concrete using only the combination of curing, the compressive strength of recycled aggregate concrete composite and maintenance adding 3% of nano alumina and splitting tensile strength were increased by 31.4%, 18.2%; at the same time, the same dosage conditions, nano alumina on the improvement of mechanical properties of recycled aggregate concrete is better than that of nano silicon oxide. In addition, low water binder ratio, strong interfacial bond between matrix and aggregate, lead to both natural concrete still, the recycled aggregate concrete with three kinds of preparation methods of modification of recycled aggregate concrete, the fracture process occurred through aggregate damage phenomenon. The resistance to chloride ion permeability The performance test show that the combination of maintenance and maintenance method or combination of nano materials, can effectively improve the durability of recycled aggregate concrete. Through the comparison of various modification methods can be concluded that the combination of maintenance at the same time adding proper amount of nano materials, recycled concrete resistance to chloride ion penetration is basic and natural concrete flat, flux of natural aggregate concrete is 283.1 C, using 3% nanometer alumina flux dosage is 315.7 C, the penetration level two are at very low levels. The performance test results also reflect the aggregate between recycled aggregate and natural aggregate performance gap. Compared with natural aggregate. Crush index of recycled aggregate, the apparent density and the consistency index is low, and the particle size distribution is poor, bibulous rate is higher.

【学位授予单位】：北京交通大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU528

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