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| 低压环境下混凝土抗冻耐久性试验及损伤模型研究 |
| Frost durability test and damage model study of concrete under low pressure environment |
| 投稿时间：2023-12-28 修订日期：2024-03-21 |
| DOI： |
| 中文关键词: 高原地区 气压条件 气孔结构 抗冻性能 冻融损伤模型 |
| 英文关键词:highland area barometric pressure conditions stomatal structure frost resistance freeze-thaw damage model |
| 基金项目:国家自然科学基金项目（面上项目，重点项目，重大项目） |
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| 中文摘要: |
| 为研究高原地区不同气压条件对混凝土抗冻性能的影响，对60kPa、80kPa、100kPa气压条件下的混凝土进行冻融循环试验，分析不同气压对混凝土抗冻性能和硬化混凝土气孔结构的影响规律，并建立了基于相对动弹性模量的混凝土冻融损伤模型和基于相对动弹性模量的混凝土抗压强度预测方程。试验结果表明：从冻融循环试验结果来看，100kPa气压条件下混凝土抗冻耐久性最佳，三种气压下混凝土抗冻耐久性排序为100kPa>80kPa>60kPa。硬化混凝土气孔结构分析可知，在环境气压降低的情况下引气剂的引气能力会受到影响，导致混凝土含气量减少，也会使气孔结构参数整体变差，从而导致低压环境下的混凝土抗冻性能下降。基于相对动弹性模量建立的冻融损伤模型和基于相对动弹性模量建立的抗压强度预测方程拟合精度较高，可以反映不同气压条件下混凝土的冻融损伤变化过程。为高原地区水利工程冻融耐久性能提供理论支撑。 |
| 英文摘要: |
| In order to study the influence of different air pressure conditions on the frost resistance of concrete in the plateau area, freeze-thaw cycle tests were carried out on concrete under the conditions of 60 kPa, 80 kPa and 100 kPa air pressure, and An analysis was conducted on the effects of various air pressures on the frost resistance and pore structure of hardened concrete. Subsequently, a freeze-thaw damage model for concrete was established based on the relative dynamic elastic modulus, along with a predictive equation for concrete compressive strength utilizing this modulus. The test results show that the freeze-thaw cycle test results show that the freeze-thaw cycle condition has the best frost durability of concrete under 100kPa air pressure, and the frost durability of concrete under three types of air pressure is 100kPa > 80kPa>60kPa。 The analysis of the porosity structure of hardened concrete shows that the air-entraining capacity of the air-entraining agent will be affected when the ambient air pressure is reduced, resulting in the reduction of the air content of the concrete, and the overall deterioration of the pore structure parameters, resulting in the decrease of the frost resistance of concrete in the low-pressure environment. The freeze-thaw damage model, along with the compressive strength prediction equation, both formulated using the relative dynamic elastic modulus, exhibit a high degree of fitting accuracy., which can reflect the freeze-thaw damage process of concrete under different air pressure conditions. It provides theoretical support for the freeze-thaw durability of water conservancy projects in plateau areas. |
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