冻融循环对陶粒混凝土动态力学性能的影响

发布时间：2018-04-17 03:17

  本文选题：冻融循环 + 动态强度　； 参考：《宁波大学》2014年硕士论文

【摘要】：本文通过静态压缩和冲击压缩实验研究冻融循环对陶粒混凝土动态力学性能的影响。利用WAW-2000微机控制万能试验机进行静态压缩实验,试样为尺寸150mm×150mm×150mm的砂浆混凝土和体积分数分别为15%、30%、40%的陶粒混凝土立方体试样及尺寸为Φ70 mm×35mm经过不同冻融循环实验的砂浆混凝土和体积分数分别为15%、30%、45%的陶粒混凝土。利用Φ74mm的分离式Hopkinson压杆(SHPB)装置进行冲击压缩实验,试样为尺寸Φ70 mm×35mm的四种陶粒体积分数经过不同周次冻融循环的混凝土试样,实验打击气压分别取0.3MPa、0.5MPa、0.7MPa。静态实验结果表明,陶粒混凝土的静态抗压强度和弹性模量随着陶粒体积分数的增加而减小;当陶粒体积分数大于30%时,抗压强度的减小程度明显变小。与砂浆混凝土不同,陶粒混凝土尺寸效应并不明显。动态SHPB实验结果表明,陶粒混凝土的动态抗压强度随着陶粒体积分数的增加而减小。在三个不同气压打击下,砂浆混凝土的动态抗压强度都明显大于陶粒混凝土的动态抗压强度;与砂浆混凝土有明显差异的是陶粒混凝土的应力应变曲线还存在平台阶段,即在应力峰值之后,且应变增加到一定值时,应力随应变增加而减小的趋势明显变小,并会出现一定的波动现象,也就是说陶粒体积的增加,有效地提高了混凝土的冲击韧性。随着冻融循环周次的增加,砂浆混凝土和各组陶粒混凝土试样的动静态抗压强度及弹性模量都随之减小。当冻融循环周次到40次后,砂浆混凝土和陶粒混凝土的试样表面脱落严重,且随着陶粒体积分数增加而趋于严重,此时陶粒混凝土的动态抗压强度几乎为未进行冻融循环的同类试样的一半。而且当冻融循环温度为-20℃~10℃时,砂浆混凝土和陶粒混凝土试样的抗压性能明显低于经过-10℃~10℃冻融循环的试样。
[Abstract]:The effect of freeze-thaw cycle on dynamic mechanical properties of ceramsite concrete was studied by static compression and impact compression experiments.The static compression experiment is carried out by using WAW-2000 microcomputer controlled universal testing machine.The samples are mortar concrete of 150mm 脳 150mm 脳 150mm, cubic sample of 40% ceramsite concrete with volume fraction of 15%, mortar concrete of 桅 70 mm 脳 35mm with different freeze-thaw cycle test and ceramsite concrete with volume fraction of 15% and 30% respectively.The impact compression test was carried out with 桅 74mm split Hopkinson compression bar (SHPB) device. The samples were concrete samples with volume fraction of four kinds of ceramsite (桅 70mm 脳 35mm) subjected to different cycles of freeze-thaw cycles. The impact pressure of the test was taken at 0.3MPa (0.3MPa) and 0.5MPA (0.7MPa), respectively.The static experimental results show that the static compressive strength and elastic modulus of ceramsite concrete decrease with the increase of the volume fraction of ceramsite, and the decrease of compressive strength becomes smaller when the volume fraction of ceramsite is greater than 30%.Different from mortar concrete, the size effect of ceramsite concrete is not obvious.The dynamic SHPB experimental results show that the dynamic compressive strength of ceramsite concrete decreases with the increase of the volume fraction of ceramsite.Under three different air pressure, the dynamic compressive strength of mortar concrete is obviously higher than that of ceramsite concrete, and the stress-strain curve of ceramsite concrete still exists in platform stage.That is, after the peak stress, and when the strain increases to a certain value, the stress decreases obviously with the increase of strain, and there will be a certain fluctuation phenomenon, that is to say, the increase of the volume of ceramsite can effectively improve the impact toughness of concrete.With the increase of freeze-thaw cycle cycles, the static and static compressive strength and elastic modulus of mortar concrete and each group of ceramsite concrete samples decrease.After freezing and thawing cycles to 40 cycles, the surface of mortar concrete and ceramsite concrete become more and more serious with the increase of the volume fraction of ceramsite.At this time, the dynamic compressive strength of ceramsite concrete is almost half of that of similar specimens without freeze-thaw cycle.Moreover, when the freezing and thawing temperature is -20 鈩，

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