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为了研究再生粗骨料在再生混凝土中的骨架增强作用和其对再生混凝土性能的影响规律,采用试验分析的方法,通过配制不同强度的再生混凝土,分析了再生粗骨料不同的取代率和最大粒径对混凝土强度、坍落度、抗压强度和抗折强度等性能的影响。结果表明:随着再生粗骨料用量的减少,再生混凝土的抗压强度逐渐提高,抗折强度趋于增加,且抗折强度随着再生粗骨料最大粒径的增大而降低,再生粗骨料的最佳粒径为9.5mm;随着再生粗骨料掺量的增加,再生混凝土的坍落度提高。在保持混凝土配合比中的单位用水量不变的前提下,随着再生混凝土中水泥用量的减少,再生混凝土砂浆的强度也随之减小。 相似文献
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1前言 大量试验检测得知回弹法检测强度设计等级低的泵送混凝土,所推定的混凝土强度值明显低于其实际强度.<回弹法检测混凝土抗压强度技术规程(JGJ/T23-92>(以下简称<规程>),是针对非泵送普通混凝土制定的.非泵送普通混凝土中很少掺外加剂或仅掺非引气型外加剂,而泵送混凝土则掺入了加气型泵送剂,砂率增加,粗骨料粒径减小,坍落度明显增大.因此有必要对回弹法检测泵送混凝土所推定的抗压强度值进行修正. 相似文献
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再生混凝土骨料含水状态与新拌混凝土的性能 总被引:9,自引:0,他引:9
研究了再生混凝土骨料在不同的含水 (自然干燥、饱和面干、完全干燥 )状态下 ,制得的新混凝土的流动性、抗压强度、劈裂张拉强度和干缩性能。试验结果表明 ,新拌混凝土的初始坍落度随着再生骨料含水量的增大而减小 ,坍落度损失也随着再生骨料含水量的增大而减小。用 10 0 %再生骨料制备的混凝土的早期强度较低 ,但经过2 8d之后 ,各种混凝土的抗压强度趋于接近。但是 ,由饱和面干状态和干燥状态的再生骨料制备的混凝土的劈裂张拉强度和干缩值明显高于其它混凝土。 相似文献
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分别对C30、C50、C60不同强度等级的废旧混凝土进行破碎,筛选得到不同粒径的再生骨料,研究再生骨料的性能指标;采用聚乙烯醇与水玻璃以1∶1比例配制成不同浓度的强化液,研究强化改性对再生骨料吸水率和压碎值的影响;将再生骨料与天然骨料复配应用于混凝土中,研究其对混凝土性能的影响。结果表明:随着再生骨料掺量的增加,再生混凝土的坍落度与扩展度总体呈现先减小后增大的趋势,当再生骨料掺量在12%~24%时,再生混凝土的坍落度为200 mm左右,28 d抗压强度达到42 MPa左右。 相似文献
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主要研究了粗骨料中针片状含量和细骨料中石粉含量对自密实混凝土工作性能及强度的影响。试验结果表明针片状粗骨料含量在4%~8%时,自密实混凝土的坍落扩展度、J型环流动度、静态离析百分率随着其含量的提高而降低,但抗压强度变化不明显,8%针片状骨料含量时,C40等级自密实混凝土T500流动时间由基准组的1.2s增加到1.7s。C25等级自密实混凝土随着石粉含量增加,抗压强度增加而流动性能和静态离析百分率下降,石粉含量对C55和C60等级的试件抗压强度影响不大,但拌合物流动性和静态离析百分率随其含量提高而下降。 相似文献
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H. E. Anderson 《Fire Technology》1968,4(1):51-58
In laboratory tests, the size of a flame front can significantly affect the rate of fire spread. The configuration factor
of a given flame shape provides a method for relating flame fronts of various widths. The author discusses an analog system
for determining the configuration factor of an irregularly shaped flame and the effects of flame width and height on the rate
of spread. 相似文献
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Taking four office buildings built in the south of Sweden in the past decade, the authors analyse in detail the effects of geometry and configuration on their use of energy. Compactness may reduce energy consumption, they conclude, but important other qualities may suffer. The authors are architects with BS Konsult AB, Stockholm. 相似文献
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《Building and Environment》2001,36(5):627-635
This work aims at relating the heating consumption of the buildings with their shape. This information is dedicated to the architects and engineers. At the beginning of the project, they need global information enabling them to find economical solutions as for energy consumption. First of all, a parameter that has been chosen to characterize the shape of the buildings is introduced. The selection of this coefficient is grounded on the necessary simplicity of its use by conceivers. Thus, the shape coefficient is defined as the ratio between the external skin surfaces and the inner volume of the building. Then, the sample of the studied buildings is described. Fourteen buildings have been chosen according to their varieties in shapes and their representativeness in current constructions. The calculation code used to evaluate the heating consumption is briefly described. This code operates the method of weighting factors. The method is quick and well adapted to the study as the 14 buildings are conceived from the same basic cell. The results show that the energetic consumption is inversely proportional to the compactness (weak shape coefficient) in case of cold severe and scarcely sunny winters. However, it can't be applied in case of mild climates, which leads to no recommendation of compactness. 相似文献
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CHAU KWONG WING 《Construction Management & Economics》2013,31(4):473-482
Plan shape indices are based on the geometry of the plan shape rather than on empirical data, and are problematic as they embrace implicit assumptions that are not tested empirically nor justified theoretically. Empirical research using data in Hong Kong confirms that these plan shape indices are much poorer predictors of unit construction costs than the variables used to construct the indices. This study also develops a method for constructing a plan shape index that is free from the unjustified assumptions implicit in existing plan shape indices; it involves an empirical cost model. Different functional specifications of the cost models are tested. The result rejects the linear model and other special case models such as semi-log and log-linear models. However, the reciprocal model is not rejected. This result suggests that a linear plan shape index can predict the amount of floor area that can be constructed with a fixed sum of money better than the construction cost per floor area. 相似文献
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工程机械企业的竞争已经从产品竞争、技术竞争,上升到服务竞争、品牌竞争.以"服务为用户创造价值" 为主题的中国质量协会工程机械分会、全国建设机械设备用户委员会和中国工程机械工业协会用户工作委员会2011年会于2011年12月10日在浙江杭州隆重召开.参会代表主要来自工程机械制造企业和施工企业,中国质量协会领导、分会领导、中国工程机械工业协会领导、中国服务专家郎志正教授等出席了会议,建筑机械化杂志等多家行业媒体对会议盛况进行了报道.会议由浙江省建设机械集团有限公司协办. 相似文献
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《Planning》2016,(4)
为了改善钢轨焊接接头热处理性能,以减小热处理加热过程轨头与轨底脚温度差,提高轨头、轨底三角区、轨底脚等薄弱部位内部组织晶粒度为优化目的,通过试验分析了热处理加热感应器的形状、加热温度、频率、功率等对轨头与轨底脚温度差的影响,发现合适的感应圈形状和尺寸比例是热处理工艺参数优化的基础,红海焊轨厂针对对外采购的感应圈,根据车间辊道线水平程度、正火控制柜功率等实际情况,自行改良了感应圈的形状尺寸比例,接头的显微组织、晶粒度等力学性能得到了显著改善。 相似文献
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阐述了建筑体形系数的节能设计要求,通过四种形状建筑设计的对比,分析了建筑外形设计对体形系数的影响,得出在体形系数限制下可以通过外形优化设计满足建筑节能设计要求。 相似文献