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SUNGWen-pei CHENKuen-suan LINHsue-chun 《浙江大学学报(A卷英文版)》2005,6(3):159-165
INTRODUCTION For some unknown reasons, perhaps caused bysalt, chlorine ions usually exist in reinforced concreteconsisting of cement, water, aggregate and additionalmaterials, and steel bars. In the presence of water, thechlorine ion reacts with iron existing in concrete andsteel bars to form Fe(OH)2 and FeCl2. The chemicalreactions seriously corrodes the surface of steel barsand damage the concrete, causing gradual decrease ofthe concrete compression and increase of its porosity,… 相似文献
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浅析影响混凝土施工质量的因素 总被引：1，自引：0，他引：1
现今的高层建筑大都采用钢筋混凝土框架或框架剪力墙结构，混凝土被大量、广泛应用。影响混凝土施工质量的因素有混凝土的原材料及混凝土在施工过程中的质量控制两个方面的因素。本文阐述了在混凝土配置过程中应尽量采取比混凝土设计标号高多级的水泥配置，严格控制混凝土的水灰比等观点，以实现混凝土施工的高质量。 相似文献
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通过在混凝土中掺入不同的钢纤维试验掺量,研究不同掺量钢纤维对混凝土早期和后期抗压强度的影响,对影响的原因进行了初步分析。 相似文献
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高强混凝土施工质量控制技术研究 总被引：1，自引：0，他引：1
在工程实际中,高强混凝土由于其抗压强度高、密实性好、结构自重轻等优越的性能得到广泛利用。通过对高强混凝土施工中易出现的质量问题的分析,提出了具体的高强混凝土施工质量控制措施,推动了高强混凝土的实际应用。 相似文献
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冻融是混凝土结构随季节变化所必须经历的阶段,随着冻融次数的增加,混凝土的表观特征和强度将发生退变.采用冻融次数为0、30、50、70、100次,对补偿收缩混凝土进行冻融循环试验,分析补偿收缩混凝土的表面特征和强度劣化趋势,发现随着冻融次数的增加,普通混凝土与补偿收缩混凝土相比,表面破坏更严重,混凝土抗压和抗折强度呈现下降趋势.冻融100次后,普通混凝土抗压、抗折强度分别下降35.2%和44.1%,而补偿收缩混凝土抗压、抗折强度分别下降30.3%和35.3%,说明适当掺入膨胀剂对提高混凝土的抗冻性有一定的作用,有利于控制和降低混凝土冻融环境下强度的退化. 相似文献
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本文针对钢筋砼受弯构件正截面计算中一些没考虑到的因素产生的超筋和少筋构件提出了一些预防措施. 相似文献
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The stress-strain curves of confined concrete were obtained based on tests of seven cross-shaped columns confined by stirrups under axial load. The experiment results showed that the strength and deformation of confined concrete can be enhanced effectively by stirrups for cross-shaped columns. Compared with the non-confined concrete, when the stirrup characteristic value is in the range of 0.046--0.230, the confined concrete compressive strengths has an increase of 8%--43%, and the strain corresponding to the peak stress of confined concrete has an increase of 25%-- 195%. According to the test results, the effects of stirrup characteristic and stirrup spacing on the compressive strength and strain of confined concrete were analysed. It is shown that the compressive strength of confined concrete has a linear relationship with the product of stirrup characteristic value and stirrup effective restraint coefficient, and the strain corresponding to the peak stress of confined concrete has a nonlinear relationship with the product of stirrup characteristic value and stirrup effective restraint coefficient. The stress-strain curve equation of confined concrete was proposed for cross-shaped columns, and the calculated curves are in good agreement with the experimental curves. 相似文献
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新的国家标准《混凝土结构工程施工质量验收规范》(GB50204-2002)的颁布和实施,对钢筋保护层厚度提出了更高的要求。钢筋保护层塑料垫块以其优异的性能、便捷的安装方法,在现浇钢筋混凝土工程中已得到了快速的推广和应用。这一技术有效提高了钢筋混凝土工程质量,克服了传统的砂浆垫块的工艺缺陷,完全满足新规范的要求。 相似文献
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邵雅静 《邢台职业技术学院学报》2012,(5):40-44
基于《混凝土强度检验评定标准》（GB／T50107．2010）的有关规定,对混凝土强度检验评定新旧标准的区别进行了分析,从应用条件、检验批构成、标准差计算、检验函数和合格条件等方面对混凝土强度检验评定方法进行了比较,并对统计法评定与非统计法评定进行了例算。 相似文献
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混凝土拌合物各自成分不同,对混凝土品质及钢筋耐久性有至关重要的影响。但人们往往忽 视了此类问题,将其提到桌面上来讨论很有意义。 相似文献
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We proposed a bilinearity constitutive curve model of fiber reinforced polymer （FRP） confined concrete which includes a parabola in the first stage and a straight line in the second stage. The FRP-confined concrete has powerful confinement status and weak confinement status leading to different equations of parabola. We analyzed the impacts of factors such as confinement ratio and restrain stiffness on confined concrete compressive strength, ultimate strain and other control parameters through finite element analysis. The results show that the confinement ratio determines the confinement status, and the increase of the confinement ratio has a limited capacity to increase the compressive strength, The deformation of confined concrete is influenced by restrain stiffness. The stronger the restrain stiffness is, the less the lateral deformation is and the greater ultimate axial strain will be. The consideration of equivalent section coefficient kse is needed in the non-circular section confined concrete. We analyzed the results and proposed boundary values of strong and weak confinement styles, a peak/inflection point stress and strain model, and a compressive strength and ultimate strain model. 相似文献
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对新拌混凝土采用了3个不同时刻作为振动的起振点,分别按照3种不同频率和振幅组合进行实验,将受振动的试件和基准（未振动）试件在标准养护室养护到一定龄期后进行抗压试验,从而判断受振动混凝土1d、3d及28d抗压强度变化趋势。测量了不同龄期的72组抗压强度,通过对实验数据进行统计分析,其中有17组强度是降低的,降低的数据在6%以内的占了16组。试验结果表明：对处于初、终凝前后混凝土材料施加试验中设计的振动,对混凝土的抗压强度有一定影响。 相似文献
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钢筋混凝土受弯构件纵向配筋率ρ的取值，现行混凝土设计规范(GB50010—2002)允许的范围是比较大的，然而在实际工程中，钢筋混凝土受弯构件内纵向配筋率ρ的大小对建筑工程质量、耐久性、经济性等方面都有很大影响。该文仅从有屈服点钢筋在钢筋混凝土梁内纵向配筋率入手，通过理论分析、经济比较，研究确定钢筋混凝土受弯构件-梁的合理纵向配筋率。 相似文献
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为了提高混凝土抗压强度预测精度,利用改进果蝇优化算法(IFOA)优化RBF神经网络的参数Spread值,建立IFOA-RBF预测模型用于混凝土抗压强度预测。模型以UCI数据库中的Concrete Compressive Strength数据集为例,以每立方混凝土中的水泥、高炉矿渣粉、粉煤灰、水、减水剂、粗集料和细集料的含量以及置放天数为网络输入,混凝土抗压强度值作为网络输出,进行仿真测试,并将结果与参考文献中的其它方法比较。结果表明:优化后的RBF网络既体现了广泛映射能力,又明显地提高了网络的泛化能力。验证了IFOA-RBF模型在混凝土抗压强度预测中的有效性。 相似文献
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为了研究补偿收缩混凝土的抗冻性能,采用慢冻法对普通混凝土和补偿收缩混凝土进行冻融对比试验。通过对比研究普通混凝土和补偿收缩混凝土冻融后质量损失、强度损失和相对动弹性模量变化趋势,从而得出补偿收缩混凝土的抗冻性能。试验结果表明,普通混凝土冻融100次后,质量损失率为2.09%,抗压强度下降35.2%,相对动弹性模量下降到60.8%;补偿收缩混凝土质量损失率为1.62%,抗压强度下降30.3%,相对动弹性模量下降到64.8%;试验三个参数指标表明添加膨胀剂有助于提高混凝土抵抗冻融破坏的能力,改善混凝土结构的损伤程度,体现了膨胀剂对混凝土的增强机理。 相似文献
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本文对混凝土抗压强度检测常用技术的原理、检测方法、强度计算和注意事项等进行了综合分析，为合理选择准确、经济、安全的检测方法提供了技术参考。 相似文献
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The effect of recycled coarse aggregate on concrete compressive strength was investigated based on the concrete skeleton theory. For this purpose, 30 mix proportions of concrete with target cube compressive strength ranging from 20 to 60 MPa were cast with normal coarse aggregate and recycled coarse aggregate from different strength parent concretes. Results of 28-d test show that the strength of different types of recycled aggregate affects the concrete strength obviously. The coarse aggregate added to mortar matrix plays a skeleton role and improves its compressive strength. The skeleton effect of coarse aggregate increases with the increasing strength of coarse aggregate, and normal coarse aggregate plays the highest, whereas the lowest concrete strength occurs when using the weak recycled coarse aggregate. There is a linear relationship between the concrete strength and the corresponding mortar matrix strength. Coarse aggregate skeleton formula is established, and values from experimental tests match the derived expressions. 相似文献
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Ten slender steel reinforced cencrete (SRC) composite columns are tested under eccentric loading conditions.Effects of concrete strength, slenderness of columns and eccentricity of the axial load are studied. The load-carrying capacity is reduced with increased slenderness ratio and eccentricity. Concrete strength has no obvious influence on eccentrically loaded columns. Then, a nonlinear numerical method of pin-ended slender columns is also presented. This method is applicable for determining the material failure load or buckling failure load of a slender steel reinforced concrete composite column. In this method both material and geometric nonlinearities are taken into account. The results of numerical analysis accord well with the test results. The test results are also compared with the results predicted by ACI318-05 and the China Specifications. 相似文献
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杨瑞新 《河北工业大学成人教育学院学报》2006,21(4):25-29
碳纤维布加固混凝土结构是一种新型加固方法。本文在试验研究的基础上,将抗拉强度很高的碳纤维布用环氧树脂预浸成为复合增强材料;用环氧树脂粘结剂沿受拉方向粘贴在要补强的柱子上,形成一个新的复合体,使补强碳纤维布与原有钢筋混凝土共同受力,增大结构的抗剪、抗弯强度和提高柱的延性。 相似文献