共查询到18条相似文献,搜索用时 187 毫秒
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《工程建设与设计》2015,(10)
为了探究冻融循环作用后沥青混合料的低温弯曲特性,论文采用小梁低温弯曲试验,研究了油石比、冻融循环次数和级配对抗弯拉强度、弯曲劲度模量和弯拉应变的影响。试验结果表明,冻融循环初期,抗弯拉强度、弯曲劲度模量和弯拉应变急剧降低,而当冻融循环次数大于15次时,三者均趋于稳定;随着油石比的增大,抗弯拉强度和弯曲劲度模量出现先增大后减小的变化趋势,当油石比为5%时,两者有最大值,而弯拉应变一直增大;当冻融循环次数相同时,抗弯拉强度和弯曲劲度模量的大小顺序是:AC 13AC 16AC 10,而弯拉应变的大小顺序为:AC 13AC 10AC 16。综合来看,AC-13混合料的低温弯曲特性最好。 相似文献
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盐冻融循环对沥青混合料低温性能的影响 总被引:1,自引:0,他引:1
采用低温弯曲试验,以最大弯拉应变比、弯曲劲度模量和应变能密度等指标分析了盐冻融循环条件下沥青混合料低温性能的衰变规律,研究了掺加纤维等添加剂后,在盐冻融循环条件下沥青混合料低温性能的改善效果.结果表明:沥青混合料经盐冻融循环后,其最大弯拉应变比、应变能密度显著减小,弯曲劲度模量增大;随着盐冻融循环次数的增加,各指标变化幅度逐渐减小;盐溶液质量分数越高、冻融温度越低,对沥青混合料的低温性能影响也越大;应变能密度与盐冻融循环次数呈指数函数变化;玄武岩纤维对盐冻融循环条件下沥青混合料低温性能的改善效果较好. 相似文献
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为获得能表征不同工况下沥青混合料力学性能的本构方程,采用沥青混合料标准马歇尔试件的单轴压缩试验数据,获得以加载速率和应力状态为自变量的动态弹性模量场模型.基于ABAQUS/VUMAT编写了材料本构的用户子程序,依据试验数据分析了模型的可靠性.分别采用沥青混合料劈裂试验中压头的竖向位移数据和沥青混合料小梁弯拉试验中的弯拉强度数据验证动态弹性模量场模型在不同工况下的通用性.结果表明:采用动态弹性模量场模型的计算结果与不同加载速率下沥青混合料的单轴压缩、劈裂和小梁弯曲等工况下的试验数据吻合较好.动态弹性模量场模型能描述沥青混合料材料参数与受力状态和加载历史的依赖性,可为复杂受力状态下沥青混合料结构的力学分析提供一种方法. 相似文献
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为对室内外老化条件下沥青混合料的动态模量特征进行比较和评价,按照北京市五环路上、中、下3个面层的结构与材料类型,在室内成型SMA-16,AC-25,AC-30沥青混合料试件,分别进行不同老化程度下的间接拉伸疲劳试验,根据时-温等效原理建立不同老化程度沥青混合料的动态模量主曲线,并与室外自然老化13a的沥青路面芯样进行对比,研究室内外老化的关系.结果表明:老化效应对沥青混合料动态模量的影响随试验温度升高而逐渐增强;沥青混合料动态模量对老化效应的敏感程度依次为:AC-25AC-30SMA-16;间接拉伸试验条件下3种沥青混合料室内外老化的动态模量主曲线差异不大,可以通过室内老化试验对室外路面沥青混合料的动态模量进行评价. 相似文献
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本文较系统地研究了C100~C150超高强混凝土的各种强度性能及变形性能,包括超高强混凝土的劈拉强度、抗折强度、与钢筋的粘接强度、棱柱体强度、应力-应变曲线特征、变形模量、泊桑比等。研究表明:随着超高强混凝土抗压强度的提高,其劈拉强度、抗折强度与抗压强度的比值,较高强混凝土的低,较普通混凝土的更低。超高强混凝土的应力-应变关系呈直线,受压破坏时呈突然爆炸式破坏,证明了超高强混凝土脆性破坏的比普通混凝土和高强混凝土进一步增大。经过研究,得出了各种强度指标、变形模量及峰值应变与混凝土抗压强度的回归关系式,加深了对超高强混凝土的力学性能的理解和认识。为今后超高强混凝土的应用也奠定了必要基础。 相似文献
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Crumb rubber concrete (CRC) is made by adding rubber crumbs into conventional concrete. This study undertakes an experimental study on the cubic compressive strength, axial compressive strength, flexural strength and splitting tensile strength of CRC specimens at both ambient temperature 20 °C and low temperature ?25 °C. The flexural stress–strain responses were also recorded. The averaged size of rubber crumbs used in the study is about 1.5 mm. Four levels of rubber contents are investigated, which are 0%, 5%, 10% and 15% by volume, respectively. The mix design aimed at 40 MPa of compressive strength and 100 mm of slump for all the CRC specimens. The results show that CRC increases its magnitude in strengths when temperature decreases, which is similar to the case of conventional concrete, but still exhibits ductility in low temperature. The conclusion from this study is that CRC may be more beneficial in its application in low temperature environments than in ambient temperature environments. 相似文献
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《Construction and Building Materials》2010,24(11):2157-2163
A study is made of the suitability of strip-prone aggregates for use in asphalt concrete water barriers in embankment dams. Standard boiling tests were used for ranking various aggregate types with respect to water susceptibility and aggregate-bitumen adhesion. Indirect tension tests (splitting tests) were used to study the effects of aggregate-bitumen adhesion on asphalt concrete tensile strength. The test results show the significant detrimental effects of using strip-prone aggregates for open-grade porous asphalt (air void 4–10%), but that aggregate-bitumen adhesion and tensile strength could be increased by adding amine or hydrated lime to the asphalt mix. However, a similar test series on dense-grade hydraulic asphalt (air void 2–3%) shows no detrimental effects of using strip-prone aggregates. Furthermore, there were no significant differences in compressive strengths or beam bending strengths and strains at failure between specimens with or without strip-prone aggregates and with or without amine added. This was the case even for specimens having been cured by exposure to 100 freeze–thaw cycles at +25 °C to −25 °C. For hydraulic asphalt, which is virtually impervious with a significant bitumen film thickness covering the aggregate particles, it does not seem required to use additives to improve the aggregate-bitumen adhesion properties. However, further testing should be done to study any long-term effects of using strip-prone aggregates. 相似文献
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冻融损伤混凝土力学性能衰减规律 总被引:2,自引:0,他引:2
为研究冻融作用对混凝土力学性能的影响,采用快冻法将混凝土盐冻或水冻至不同损伤程度后,测其动弹性模量、抗折强度、抗压强度和劈裂抗拉强度.以动弹性模量为损伤变量,分析了冻融损伤与抗折、抗压强度之间的关系,采用回归分析的方法建立了抗折强度衰减方程.结果表明,混凝土抗压、抗折、劈裂抗拉强度以及动弹性模量均随冻融循环作用次数的增加而逐步降低;抗折、劈裂抗拉强度以及动弹性模量的衰减速率随冻融循环作用次数的增加而不断增大,但抗压强度的衰减速率则是先增大后减小;在冻融循环次数相同的情况下,含气量越高、水灰比越低,混凝土的强度损失越小,其力学性能损失的大小顺序依次为:抗折强度和劈裂抗拉强度、动弹性模量、抗压强度;冻融损伤与抗折强度的相关性较好,但与抗压强度的相关性较差,当冻融损伤小于40%时,混凝土的抗压强度一般不低于其初始强度的70%. 相似文献
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This study is aimed at determining the relationship between asphalt film thickness and aging characteristics of various hot-mix asphalt (HMA) mixtures. Resilient modulus and indirect tensile strength tests were conducted on the Superpave Gyratory-compacted specimens with five different asphalt film thicknesses in order to determine an optimum asphalt film thickness. From the relationships between the asphalt film thickness and resilient modulus and indirect tensile strength test values of the short and long-term aged samples, optimum asphalt film thickness has been determined about 9–10 μm. The minimum void content of mineral aggregate (VMA) to obtain this optimum asphalt film thickness can be calculated as 15.2%. 相似文献