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快速鉴定集料的碱活性是当前世界各国科学家一致追求的目标。本文详细介绍我们所提出的快速法的各种试验条件选择的依据。通过加温、加压、加碱等强化碱—集料反应条件的试验与显微观察,论证了利用测长法研究、鉴定碱—集料反应时,提高试体养护温度和压力是可能的。对硅酸型活性集料最佳试验温度为150℃,此外还要控制在一定时间内。同时还介绍了水泥中碱含量,浸泡液碱浓度、水灰比、试体预养条件、集料粒径、水泥与集料之比等对膨胀率的影响。在上述各种试验条件的基础上,根据研究、鉴定碱—集料反应试验要求,通过选择适宜的试验条件研究碱—集料反应。证明选择适宜的强化条件进行试验不但效果好,还可大大加快反应速度,得到一些短期内难以得到的规律。 相似文献
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为研究集料微观结构对碱活性快速检测方法中对岩石适应性的影响,采用混凝土棱柱体法、快速砂浆棒法、压蒸法、中国快速砂浆棒法研究了波茨坦砂岩的膨胀行为,并研究了膨胀后试件的微观结构.结果表明:快速砂浆棒法、压蒸法、中国快速砂浆棒法均不能正确判定波茨坦砂岩的碱活性,主要是由于这些方法使用的集料中含大量粒径太小、不能反映该砂岩特殊结构特征的颗粒;对该类岩石,除活性组分的类型、数量外,岩石的微观结构特征能够显著影响碱-集料反应发生的位置和膨胀行为.在快速法中采用能够保持岩石原有结构特征的集料粒径是正确鉴定类似波茨坦砂岩微观结构岩石及其它非均质、多矿物岩石碱活性的关键. 相似文献
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北京地区混凝土集料的碱活性及碱—集料反应 总被引:3,自引:0,他引:3
本文主要介绍北京地区部分混凝土集料碱活性的鉴定结果,以及北京市个别混凝土工程发生碱-集料反应的诊断结果。现有资料表明,北京地区存在大量碱活性集料。这些集料会与水泥中的碱发生化学反应,使混凝土膨张开裂,从而对混凝土工程的物理力学性能及耐久性等造成不良影响,这将导致重大经济损失,应当引起有关部门的重视。 相似文献
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由于水泥中的碱和某些集料之间的化学反应将引起混凝土膨胀开裂甚至破坏,许多国家在标准中有水泥碱含量的限制,也有鉴定集料碱活性的标准。本文作者针对我国有关标准存在的问题提出许多建议,值得考虑研究。 相似文献
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为研究和改进中国压蒸法检测砂岩类集料碱活性的适应性,以混凝土棱柱体法为基准,采用中国压蒸法研究了9种国内外砂岩类集料的碱活性,同时研究了集料颗粒粒径对砂浆试体压蒸膨胀行为影响.结果表明:中国压蒸法不能准确评定某些砂岩集料的碱活性且砂浆试体膨胀结果与混凝土中的膨胀结果相关性较差;颗粒粒径0.16~0.63 mm不是最敏感粒级;采用粒级1.25~2.50 mm、试体尺寸20 mm×20 mm×80 mm,在150℃、1 mol/LNaOH溶液中压蒸30 h可以大大改善中国压蒸法对砂岩类集料的适应性. 相似文献
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Summary A method has been developed for the determination of soda ash and sodium hydroxide in vegetable oil-alkali mixtures as a check
on proportioning equipment feeding oil and alkali. The method depends upon the potentiometric titration in one step of free
alkali and soap, using a pH meter and the glass electrode-calomel electrode assembly. The analysis is sufficiently rapid to
serve as a convenient control in a continuous refining process. 相似文献
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介绍碱木素的结构特性和PS碱木素磺酸盐的制备方法及其应用实例,并通过实际数据论述了碱木素堵剂的封堵机理。指出我国造纸黑液中含有的大量碱木素,可应用于稠油开采,从而化害为利。 相似文献
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Igor Z. Zhuravlev Valentin A. Kanibolotskii Vladimir V. Strelko Anatoly I. Bortun Lyudmila N. Bortun Sergei A. Khainakov 《溶剂提取与离子交换》2013,31(3):635-648
ABSTRACT Spherically granulated sodium aluminosilicophosphate (APS) of the empirical formula Na4Al4PS18O46.5 18H2O was synthesized by a gel method. The APS was characterized by elemental analysis, X-ray diffraction, TGA and 27AI, 28Si and 31P MAS NMR spectroscopy methods. Ion exchange of alkali, alkaline earth and some other divalent metal cations by APS was studied in batch conditions. It was found that the APS has a cation exchange capacity of 2.5 meq/g and exhibits rapid kinetics of ion exchange. The ion exchange isotherms of alkali, alkaline earth and some other divalent cations were determined and the corrected selectivity coefficients as a function of metal loading were analyzed. It was found that APS exhibits a high affinity for cesium ion, a moderate affinity for some heavy metal cations (Pb2+, Zn+) and a low affinity for alkali and alkaline earth metal ions. A testing of the APS in complex solutions suggests that it could be a promising exchanger for treatment of some specific nuclear waste and contaminated environmental and biological liquors from radioactive cesium and toxic heavy metal ions. 相似文献
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We examine the mass transfer consequences of the nonequilibrium scavenging of condensible vapor (Na2SO4) by suspended solid particles (MgO) within combustion gas boundary layers (BLs) using an extension of our 'flash-evaporation' technique (Rosner and Liang, 1986) and laser light scattering methods. In contrast to the result of introducing additives which form miscible condensates with the primary alkali sulfate on a sufficiently cold deposition target—a situation which leads to vapor deposition rate increases (Liang and Rosner, 1986), additives which form nonvolatile, submicron particles in the main-stream, capable of scavenging the alkali vapor(s), reduce total alkali deposition rates at all levels. This result indicates that the thermophoretic diffusivity of such 'getter' particles is smaller than the Fick diffusivity of the scavenged alkali sulfate vapor. Both nonequilibrium laminar BL-theory (Castillo and Rosner, 1987) and our flash evaporation-light scattering experiments reveal that the alkali mass transfer rate reduction factor correlates with the product Nprp2—a quantity proportional to the scavenging particle cloud external surface area per unit volume. These results also imply that, in practice, finely divided inorganic sulfur getters, present in the 'fire-side' boundary layer at sufficiently high number densities, would also suppress the total deposition rate of alkali compounds on heat exchanger surfaces. 相似文献
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<正> 在氯化法制造纸浆的过程中,氯气与经过碱液处理的植物纤维原料作用,使其中的木素成为氯化木素,以便用稀碱除去.本工作的目的是寻求在氯化法的条件下氯与木素的反应速度,并试图明确该反应的性质. 相似文献