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针对在干旱、多风等严酷气候环境条件下的机场场道工程道面混凝土施工作业中易发生混凝土假凝,导致混凝土做面拉毛工艺操作困难,从而出现道面平均纹理深度不合格、观感差等质量问题,为了提高施工质量,开展了干硬性混凝土假凝的原因分析及防治研究,从水泥材料的铝酸三钙含量、粉磨工艺、碱含量、比表面积等性能参数中试验分析总结,得出了适用于西北干旱多风地区机场场道工程道面混凝土用水泥的参数选择建议,通过水灰比对混凝土产生假凝的影响总结出不同气温、风力条件下的最佳水灰比,应用了增加一道覆盖塑料布工艺并总结出不同气温、风力条件下所需的覆盖时间,多措并举,有效降低了混凝土假凝发生概率,保证了混凝土施工质量。 相似文献
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裂缝是机场沥青混凝土道面的常见病害类型之一,会对道面的结构性能和使用性能造成影响,缩短道面使用寿命及降低机场运行安全裕度。本文针对机场沥青混凝土道面产生裂缝类病害的原因进行简要分析,并提出相应的维修办法,为应对此类问题提供相关的参考。 相似文献
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为解决机场道面达到设计寿命前发生疲劳破坏的问题,提出将预应力混凝土技术应用于机场道面工程.采用后张法对机场道面混凝土小梁施加预应力,设计三分点弯曲加载方案对96根混凝土小梁进行弯曲、抗折和疲劳试验.结果表明:施加预应力后,竖向荷载作用下小梁的挠度减小了2.99%~5.56%,拉应力数值及拉应力区显著减小;抗折强度提高了11.26%~59.42%,裂缝数量和宽度都明显减小;平均疲劳寿命增大了3.18~5.99倍,且随预应力的增大而增大,预应力混凝土弯曲疲劳寿命服从双参数Weibull分布,相关系数达到0.95以上.基于Weibull分布建立了反映应力水平S和疲劳寿命N关系的双对数疲劳方程. 相似文献
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碳纤维混凝土具有良好的电热效应,可将其用于机场道面的融雪化冰,该方法是当前机场融雪除冰的方式之一。文章探讨了影响碳纤维混凝土机场道面融雪化冰的因素,主要包括碳纤维混凝土层厚度,通电时间及碳纤维掺量,粗骨料粒径,裂缝宽度,环境温度与冰层厚度,除冰功率等。 相似文献
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乙烯酮(双乙烯酮)是十分重要的化工中间体,其下游产品较多。江苏某化工厂开发生产乙烯酮(双乙烯酮)下游产品三十多个,年生产规模三万多吨,是国内以乙烯酮(双乙烯酮)为中间体生产精细化学品的综合骨干企业。针对乙烯酮(双乙烯酮)下游产品废水特点,该厂结合企业实际,开展了产品优化,结构调整,清洁生产,资源循环利用,节水降耗等工作,从源头削减了污染物的生产。同时投资二千多万元新建预处理装置三套,6000m3/d废水生化处理装置一套,使全厂乙烯酮(双乙烯酮)下游产品的废水得到了有效的治理。 相似文献
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我厂3号回转窑(Φ4m×60m)生产线在1996年年底由SP窑(产量912t/d)改为NSP窑(产量1320t/d),预分解系统为四级旋风预热器带离线式分解炉 相似文献
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The objective of the study was to explore the effect of the degree of deacetylation (DD) of the chitosan used on the degradation rate and rate constant during ultrasonic degradation. Chitin was extracted from red shrimp process waste. Four different DD chitosans were prepared from chitin by alkali deacetylation. Those chitosans were degraded by ultrasonic radiation to different molecular weights. Changes of the molecular weight were determined by light scattering, and data of molecular weight changes were used to calculate the degradation rate and rate constant. The results were as follows: The molecular weight of chitosans decreased with an increasing ultrasonication time. The curves of the molecular weight versus the ultrasonication time were broken at 1‐h treatment. The degradation rate and rate constant of sonolysis decreased with an increasing ultrasonication time. This may be because the chances of being attacked by the cavitation energy increased with an increasing molecular weight species and may be because smaller molecular weight species have shorter relaxation times and, thus, can alleviate the sonication stress easier. However, the degradation rate and rate constant of sonolysis increased with an increasing DD of the chitosan used. This may be because the flexibilitier molecules of higher DD chitosans are more susceptible to the shear force of elongation flow generated by the cavitation field or due to the bond energy difference of acetamido and β‐1,4‐glucoside linkage or hydrogen bonds. Breakage of the β‐1,4‐glucoside linkage will result in lower molecular weight and an increasing reaction rate and rate constant. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 3526–3531, 2003 相似文献
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Conclusions It is significant that the purification on a single passage of viscose through porous ceramic corresponds to the result of a two-stage filtration of it in industrial filter-presses with standard fillings.Kiev Combine. Kiev Technological Institute of Light Industry. Translated from Khimicheskie Volokna, No. 3, pp. 20–22, May–June, 1969. 相似文献
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A refined nonlinear value of the main parameter of a material, i.e., the elongation modulus versus the instant temperature value, was suggested for introduction into the computational algorithm of tempering stresses. 相似文献