| 摘要: |
| 通过不同起冻时刻早期受冻混凝土服役性能的测试，分析了起冻时刻对混凝土损伤形态、强度损失、相对动弹性模量、渗透性及孔隙结构的影响规律及影响机理.结果表明：起冻时刻对混凝土服役性能的影响程度表现为2.0h受冻最显著，05h受冻与8.0h受冻损伤程度相当、次之，1,3d受冻时损伤程度最小且随着起冻时刻的推迟损伤程度减轻；受冻混凝土劈拉强度损失最显著，相对动弹性模量损失次之，抗压强度损失最小；3d受冻试件的抗渗性略差于未冻混凝土，1d受冻试件更差，而05，2.0，8.0h受冻试件最差，甚至超出AutoClam设备的测试范围.随着起冻时刻的推迟，终凝后受冻混凝土的孔隙结构趋近于未冻混凝土；初凝前受冻混凝土部分损伤可修复，浆体自身、浆体与粗骨料间有肉眼可见裂缝，孔径0～006mm的弦长频率明显降低，各孔径梯度的含气量（体积分数）均不同程度增大；初凝后终凝前受冻混凝土浆体自身、浆体与粗骨料间均有明显裂缝，细骨料颗粒显露明显，孔径170～400mm的弦长频率、孔径200～400mm的含气量明显增大. |
| 关键词: 混凝土 早期受冻 起冻时刻 服役性能 孔隙结构 |
| DOI：103969/j.issn.1007 9629201803007 |
| 分类号: |
| 基金项目:国家自然科学基金资助项目（51308441，51678473）；教育部“创新团队发展计划”项目(IRT_17R84)；陕西省自然科学基础研究计划（2016JM5073） |
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| Damage Study on Service Performance of Early Frozen Concrete |
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HU Xiaopeng, ZHAO Nan, YANG Chao, NIU Ditao
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School of Civil Engineering, Xian University of Architecture and Technology, Xian 710055, China
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| Abstract: |
| The influence and damage mechanism of frozen up time on the damage mode, compressive strength, splitting tensile strength, relative dynamic elastic modulus, permeability and pore structure of early frozen concrete were studied by the service performance test for the early frozen concrete with different frozen up times. The results show that the influence is the most significant for the concrete with frozen up time of 2.0hours, and the influence is next to that for the concrete with frozen up time of 05 and 8.0hours. Moreover, the damage degree of frozen concrete after final set（1,3d） is the slightest and reduces gradually with the increasing frozen up time. In addition, the degradation of splitting tensile strength is the greatest, the reduction of dynamic elastic modulus takes the second place and the degradation of compressive strength is slightest. Furthermore, the anti permeability of concrete with frozen up time of 3days is slightly worse than that of non freezing concrete, and the anti permeability of concrete with frozen up time of 1day is worse than that of 3days, the anti permeability of concrete frozen at 05, 2.0 and 8.0hours are the worst and even beyond the test range of AutoClam equipment. The pore structure of concrete frozen after final set is close to that of non freezing concrete with increasing frozen up time. With regard to the concrete frozen before initial setting time, the frost damage can be partially repaired, some visible cracks appear in the paste or paste aggregate interface, the chord length frequency of 0006mm reduces significantly and the air contents(by mass) under different chord lengths increase in varying degrees. For the concrete frozen between initial set and final set, notable cracks at the paste or paste aggregate interface and fine aggregate particles are observed, moreover, the chord length frequency of 170400mm and the air content of 200400mm increases significantly. |
| Key words: concrete early frozen frozen up time service performance void structure |
