EXPERIMENTAL RESEARCH ON CRYOGENIC TEMPERATURE COMPRESSIVE STRENGTH OF CONCRETE UNDER COUPLING ACTION OF KEY INFLUENCING FACTORS
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摘要: 采取浸泡和烘烤方式对试件混凝土进行不改变其内部孔隙结构和分布的含水率预处理,然后通过不同低温下轴压试验系统地探讨作用的低温(-40~-180 ℃)和混凝土的含水率(1.5%~5.5%)、强度等级(C30、C40和C50)等3个关键因素对混凝土低温受压强度的影响规律并拟合出相应的耦合函数。试验结果表明:含水率和强度等级越高、作用的低温越低时,试件破坏声响越大、清脆,脆性更显著、偏心现象也渐显现,破坏后形成的上下锥体残块差异变大且碎块变得细碎、破坏面粗骨料被劈裂现象也更明显。混凝土受压强度低温下有较大的提升,混凝土的含水率越高、强度等级越低以及作用的低温越低时这种情况更加明显,且与含水率间更近于线性关系。3个关键因素中混凝土含水率和低温的作用对混凝土受压强度的影响明显,而混凝土强度等级的影响要弱。Abstract: The water content of concrete specimen was pre-treated by soaking and baking without changing the internal pore structure and distribution, then through the axial compressive test at different cryogenic temperatures, the influencing regularities of three factors including cryogenic temperature action (-40 ℃ to -180 ℃), concrete water content (1.5% to 5.5%) and strength grade (C30, C40 and C50) on cryogenic temperature compressive strength of concrete were systematically discussed, and corresponding coupling function was fitted out. The test results showed that the higher the concrete water content and strength grade, and the lower the cryogenic temperature, the greater the damage-induced sound and crispness extent, meanwhile the more obvious the brittleness failure and eccentricity feature; the broken residual blocks of the upper and lower cones became more different and the fragments became finer, and the phenomenon of aggregate splitting was more apparent. The compressive strength of concrete increased greatly at cryogenic temperature, the higher the concrete water content, and the lower the concrete strength grade and the cryogenic temperature, the more obvious this changing trend, and it was closer to the linear relationship with increase in concrete water content. Among the three key factors, the effects of concrete water content and cryogenic temperature on concrete compressive strength were obvious, but the influence of concrete strength grade was weaker.
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Key words:
- concrete /
- cryogenic temperature /
- water content /
- concrete strength grade /
- compressive strength
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