液体无碱速凝剂的研制及应用研究

发布时间：2018-05-27 03:00

  本文选题：碱 + 液体速凝剂　； 参考：《郑州大学》2014年硕士论文

【摘要】：液体无碱（或低碱）速凝剂(Liquid Alkalifree Accelerator,LAA)是一种喷射混凝土所使用的外加剂，能显著缩短混凝土的凝结硬化时间。跟传统碱性粉状速凝剂相比，它具有碱含量低、在拌合料中分散充分以及施工时空气中粉尘浓度低等优点，能有效减小在施工过程中对施工人员的腐蚀伤害，并且能提高喷射混凝土的强度和避免喷射混凝土的质量大幅度波动。因此，开发液体无碱（或低碱）速凝剂以替代传统速凝剂已成为当前有关混凝土及施工技术方面研究的热点之一。 本文较为系统地阐述了速凝剂的发展历史和国内外的研究应用现状，通过分析现有速凝剂的不足，进而指出研究开发液体无碱（或低碱）速凝剂的必要性和可行性，并进行了大量的理论分析和试验探索，得出主要研究成果如下: （1）提出了制备高效液体无碱速凝剂的关键是获得高铝离子含量的稳定溶液。研究了铝离子在溶液中稳定存在的条件，提出了高浓度铝离子合成思路。 （2）进行了无碱液体速凝剂配制研究，得出无碱液体速凝剂优化配比为：AlF3理论含量7％～8％，硫酸铝含量43％±2％，，配位剂掺量为1.5%。以此制备的速凝剂稳定性好，对于大部分普通水泥来说，速凝剂用量在5％时初凝时间小于3min，终凝时间小于5min，1d抗压强度可达到10MPa左右，28d抗压强度比大于100％。 （3）研制了无碱速凝剂SNJ-2（基础配方），其生产原料易得、工艺简单、成本低廉，用量少（掺量3%～5%）。通过SNJ-2对商品水泥的适应性研究，提出了具有良好适应性水泥的建议：对于P.O42.5水泥，指标参考值：28d抗压强度≥48MPa，比表面积：320～350m2/kg，同时应重视水泥助磨剂与速凝剂的相容性问题。 （4）探讨了速凝组分的速凝机理，结果表明：以Al2（SO4）3溶液、含Al络合物等复合而成的无碱速凝剂主要是通过形成钙矾石（AFt）和C3AH6而导致水泥浆体的快速凝结；溶液中Al3+或Al的络合物起到的是速凝作用，而F-在速凝剂溶液中起增溶作用，在水泥水化体系中起缓凝作用。 （5）针对特殊水泥（基础配方不适用的水泥）进行了速凝剂配方的调整，建立了特殊水泥速凝剂调配方法，制备了各项性能优良的液体低碱速凝剂SNJ-3和SNJ-4。经工程应用证明，该速凝剂具有早强、小时强度增进率高、回弹低且无后期强度损失等优点。
[Abstract]:Liquid Alkalifree accelerator LAA (liquid Alkalifree accelerator LAA) is a kind of admixture used in shotcrete, which can shorten the setting and hardening time of concrete. Compared with the traditional alkaline powder accelerator, it has the advantages of low alkali content, full dispersion in the mixing material and low dust concentration in the air during construction, which can effectively reduce the corrosion damage to the construction personnel during the construction process. And it can improve the strength of shotcrete and avoid the large fluctuation of shotcrete quality. Therefore, the development of liquid alkaline-free (or low-alkali) accelerators to replace traditional accelerators has become one of the hotspots in the research of concrete and construction technology. In this paper, the history of the development of the accelerator and the present research and application situation of the accelerator at home and abroad are described systematically. By analyzing the deficiency of the existing accelerator, the necessity and feasibility of the research and development of the liquid accelerator without alkali (or low alkali) are pointed out. A large number of theoretical analysis and experimental exploration have been carried out, and the main research results are as follows: 1) the key of preparing high efficiency liquid alkali-free accelerator is to obtain stable solution with high aluminum ion content. The conditions for the stable existence of aluminum ions in solution were studied, and the synthesis of high concentration aluminum ions was put forward. 2) study on the preparation of alkali-free liquid accelerator. The optimum ratio of alkali-free liquid accelerator is 7% AlF3, 43% 卤2% aluminum sulfate and 1.5% coordination agent. For most common cement, the initial setting time is less than 3 mins and the final setting time is less than 5 mins. The compressive strength of the accelerator can reach about 28d of 10MPa or more than 100d. The basic formula of SNJ-2 (basic formula) is easy to obtain raw material, simple process, low cost and low dosage. Based on the research on the adaptability of SNJ-2 to commercial cement, some suggestions are put forward: for P.O42.5 cement, the compressive strength of P.O42.5 cement is 鈮

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