碱激发粉煤灰基地质聚合物强化增韧及耐久性能研究

发布时间：2018-02-12 20:38

本文关键词： 碱激发粉煤灰强化增韧苯丙乳液高温　出处：《西安建筑科技大学》2014年博士论文　论文类型：学位论文

【摘要】：作为一种可实现工业固体废弃物高附加值资源化利用的新型绿色建筑材料，地质聚合物是当前材料领域研究的热点课题之一；本文在粉煤灰基地质聚合物研究现状的基础上，针对其抗压强度较低及韧性差的缺陷，开展了新型激发剂、矿物掺合料、苯丙乳液、多种纤维等对其进行强化增韧研究；考察了粉煤灰基地质聚合物的耐久性能，并采用现代分析方法对其矿物相、微观结构及形貌特征等进行了表征。探索了不同离子在碱激发粉煤灰基地质聚合形成过程中的作用机理，成功地制备出了耐候性优良的苯丙乳液增韧改性的粉煤灰基地质聚合物，以及耐高温性优良的纤维强化增韧的粉煤灰基地质聚合物，主要的研究内容及取得的结果如下： (1)考察了单一激发剂LiOH、KOH、NaOH、Na2SiO3、Na2CO3及K2CO3对碱激发粉煤灰基地质聚合物力学性能的影响，结果发现激发剂的活性从小到大的顺序为：K2CO3Na2CO3LiOHKOHNaOHNa2SiO3。在二元复合激发剂中发现Na2SiO3+KOH的激发活性最高，所制备的试件经85℃养护9h后，其3d抗压强度为54.08MPa，表明Na+和K+具有协同效应：Na+较强的水化能力易于形成Si(OH)4单体，K+可加速Si(OH)4和Al(OH)4-四面体之间的缩聚和重组，形成更多的Q44结构单元，微观结构更加密实。 (2)以硅灰为硅源，氢氧化铝为铝源，配制不同Si/Al摩尔比的地质聚合物，考察了氢氧化铝在不同煅烧温度中形成的矿物相对地质聚合物力学性能的影响，结果表明勃姆石与-Al2O3的水化活性均低于水铝石的水化活性。 (3)硅灰和矿渣均能有效地对碱激发粉煤灰地质聚合物进行强化增韧，当硅灰掺量为10wt%时，可形成数量更多的活性Si(OH)4，表现为试件小孔(20nm)体积百分数增加，抗压强度增大，但抗冻融性能降低。当矿渣掺量为30wt%时，试件28d的抗压强度为77.5MPa，矿渣中解聚的玻璃体与粉煤灰中的Si(OH)4，首先形成溶胶，随后纳米溶胶转变为相互搭接的树枝状凝胶体，最终发展成结构致密的地质聚合物凝胶。提出了以“孔径弯曲度”衡量试件的力学性能，试验结果表明孔径弯曲度越大，力学性能越高。 (4)建立了苯丙乳液强化增韧粉煤灰基地质聚合物的新方法，当掺入1wt%的苯丙乳液，其28d的抗压强度为42.11MPa，抗折强度为6.30MPa，较不掺乳液样品分别提高了62%和115%。提出了苯丙乳液的增韧机理：苯丙乳液可以适量降低反应体系的Zeta电位而加速地质聚合反应进程；还可以与硅氧四面体或铝氧四面体上的羟基通过缩聚反应形成互穿的网络结构；部分苯丙乳液与地质聚合物材料中的水分子结合，具有保水作用，可维持连续的水化反应，从而增强其力学性能。 (5)探讨了玄武岩纤维、有机纤维、蛋白纤维和陶瓷纤维在矿渣/粉煤灰地质聚合物中的增韧效果，发现玄武岩纤维的增韧效果最佳，样品28d的抗折强度达到5.9MPa，较不掺纤维样品（3.2MPa）提高了84.3%。提出了玄武岩纤维的增韧机理：在碱性环境中它们可以反应形成新的无机硅酸盐凝胶；三轴压缩试验(Mechanical Test System，MTS)的应力-应变结果表明玄武岩纤维可提高钢渣/矿渣/粉煤灰(2:2:6)地质聚合物胶砂的最大弯曲应力应变；所制备地质聚合物混凝土3d的抗压强度超过30MPa，28d的抗压强度达到65.3MPa。 (6)耐高温实验结果表明在150-1200℃热处理过程中，矿渣/粉煤灰地质聚合物的抗压强度随温度的上升而增大，但当温度超过500℃，由于莫来石、石英等转化为钙铝黄长石和拉长石，，致使其微观结构呈现大量的孔洞，力学性能降低。基于热应力理论分析，在高温(900℃)环境中，玄武岩纤维可提高材料的热应力断裂抵抗因子而提高其热稳定性。 (7)考查了苯丙乳液/粉煤灰基地质聚合物的耐候性能(36个月)，发现其在空气中随着龄期的延长不易风化，且会持续发生反应，致使其力学性能提高。
[Abstract]:As a kind of industrial solid waste with high added value of new green building materials recycling, geopolymer is one of hot research topics in the field of materials; based on the research status of ash basedgeopolymeric powder on the defects of the low compressive strength and poor toughness, carry out a new mineral activator. The admixture, styrene acrylic emulsion, a variety of fiber on the strengthening and toughening research; durability of fly ash based geopolymer was investigated, and the use of modern analytical methods of mineral phases, microstructure and morphology characteristics were investigated. Different ions in alkali activated fly ash based geopolymer formation mechanism the study, prepared by fly ash basedgeopolymeric modified styrene acrylic emulsion toughened with excellent weatherability, high temperature resistance and excellent fiber toughening powder The main research content and results of ash base polymer are as follows:
(1) the effect of the single agent LiOH, KOH, NaOH, Na2SiO3, Na2CO3 and K2CO3 influence on the property of alkali activated fly ash basedgeopolymeric mechanics, found that the activity of activator from small to large order: stimulating activity of K2CO3Na2CO3LiOHKOHNaOHNa2SiO3. found Na2SiO3+KOH in two yuan compound activator in the highest prepared specimen by 85 C Maintenance after the 9h, the 3D compressive strength of 54.08MPa, indicating that Na+ and K+ have synergistic effect: Na+ strong hydration ability to form Si (OH) 4 monomer, K+ can accelerate Si (OH) 4 and Al (OH) and recombinant 4- polycondensation between tetrahedra, forming Q44 structure more. The micro structure is more dense.
(2) with silica as silicon source, aluminum hydroxide as aluminum source, geological polymer with different Si/Al molar ratios, the effects of aluminum hydroxide formed at different calcination temperature of minerals in the mechanical properties of geopolymer, results show that the hydration activity of hydration activity of boehmite and -Al2O3 were lower in diaspore.
(3) silica fume and slag are effective on Alkali Activated Fly Ash Geopolymer strengthening and toughening, when silica fume was 10wt%, can form a more active Si number (OH) 4, as the specimen hole (20nm) volume fraction increased, compressive strength increased, but decreased when the freeze-thaw resistance. The slag content was 30wt%, compressive strength of 28d is 77.5MPa, and the fly ash slag depolymerization in the vitreous body in the Si (OH) 4, first formed sol, then nano sol into overlapping dendritic gel, eventually develop into the dense structure of geological polymer gel presented to the "aperture. Bending" to measure the mechanical properties of the specimen. The experimental results show that the greater the degree of aperture bending, mechanical performance is higher.
(4) established a new method of emulsion toughening geopolymer based on fly ash, when the Styrene Acrylic Emulsion Doped with 1wt%, the 28d compressive strength is 42.11MPa, flexural strength is 6.30MPa, respectively, less sample mixed emulsion increased by 62% and 115%. proposed toughened styrene acrylic emulsion machine: benzene acrylic emulsion can amount to reduce the Zeta potential of the reaction system and accelerate the geopolymerization process; also with silicon oxygen tetrahedron or tetrahedral on hydroxyl by polycondensation reaction to form interpenetrating network structure; water molecules emulsion and geological polymer materials in combination with water retention, can maintain continuous hydration reaction thus, enhance its mechanical properties.
(5) of basalt fiber, organic fiber, protein and ceramic fibers in the toughening effect of slag / Fly Ash Geopolymer of basalt fiber toughening effect best, sample 28d and flexural strength reached 5.9MPa, less fiber samples (3.2MPa) improves the proposed toughening mechanism of basalt fiber: 84.3%. in alkaline environment they can react to form a new inorganic silicate gel; three axial compression test (Mechanical Test, System, MTS) the stress-strain results show that basalt fiber can improve the slag / slag / fly ash (2: 2:6) geopolymer mortar maximum bending stress and strain; the compressive strength of geopolymer preparation concrete 3D exceeds 30MPa, the compressive strength of 28d reached 65.3MPa.
(6) the experimental results show that the high temperature at 150-1200 DEG C during heat treatment, the compressive strength of slag / Fly Ash Geopolymer with temperature increased, but when the temperature exceeds 500 degrees, due to mullite and quartz into gehlenite and Labradorite, the microstructure presents large holes. The mechanical properties decreased. The thermal stress based on the theoretical analysis, in the high temperature (900 DEG C) in the environment, the basalt fiber can improve material thermal stress fracture resistance factor and improve its thermal stability.
(7) the weatherability of styrene acrylic emulsion / Fly Ash Based Geopolymer has been examined for 36 months. It is found that it is not easy to weathering in the air with the extension of age, and it will continue to react, resulting in the improvement of its mechanical properties.

【学位授予单位】：西安建筑科技大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：TU52

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