| 引用本文: | 武芳文,何岚清,段钧淇,王广倩,刘来君,杨飞.PVA-ECC高温冷却后力学特性与微观损伤机理[J].哈尔滨工业大学学报,2024,56(9):140.DOI:10.11918/202302033 |
| WU Fangwen,HE Lanqing,DUAN Junqi,WANG Guangqian,LIU Laijun,YANG Fei.Mechanical properties and microscopic damage mechanism of PVA-ECC after high-temperature cooling[J].Journal of Harbin Institute of Technology,2024,56(9):140.DOI:10.11918/202302033 |
|
| |
|
|
| 本文已被：浏览 628次 下载 939次 |
码上扫一扫！ |
|
|
| PVA-ECC高温冷却后力学特性与微观损伤机理 |
|
武芳文1,何岚清1,段钧淇1,王广倩1,刘来君1,杨飞2
|
|
(1.长安大学 公路学院,西安 710064;2.长安大学 建筑工程学院,西安 710061)
|
|
| 摘要: |
| 为研究工程水泥基复合材料（engineered cementitious composite,ECC）高温后的力学性能和微观特征,对ECC进行了高温后材料力学性能试验和微观特征观测。对常温（25 ℃）、200 ℃、300 ℃、400 ℃及500 ℃自然冷却和喷水冷却后的ECC试件开展了抗压和抗折性能试验,并结合扫描电镜分析了ECC微观结构损伤特征以及探究了ECC高温后损伤机理。实验结果表明:高温后ECC表面未发生剥落,500 ℃以内未见爆裂现象,随着温度升高,纤维由混凝土表面逐渐向内部熔化,且失水增多,最大烧失率13.9%；力学性能方面,ECC自然冷却后抗压强度随温度升高呈现先降低后升高再降低的现象,而喷水冷却后抗压强度随温度的升高单调降低,且强度降低显著；高温后抗折强度随温度升高逐步下降,自然冷却降低幅度较喷水冷却显著；结合微观结构变化,ECC经历高温时,纤维部分熔化导致纤维与基体的黏结性能减弱；随着温度升高水化产物之间逐渐呈现独立存在的分散体,但喷水冷却后未水化颗粒二次水化现象明显,使ECC抗折强度较自然冷却提升17%。ECC具有良好的热稳定性,且冷却方式影响ECC材料的表观特性、力学性能和微观特征。 |
| 关键词: 桥梁工程 力学特性 高温试验 ECC 微观结构 冷却方式 |
| DOI：10.11918/202302033 |
| 分类号:U444 |
| 文献标识码:A |
| 基金项目:国家自然科学基金(52378121);国家重点研发计划(2021YFB2601000)；陕西省自然科学基础研究计划重点项目(2022JZ-32)；中央高校基本科研业务费专项资金(300102212212) |
|
| Mechanical properties and microscopic damage mechanism of PVA-ECC after high-temperature cooling |
|
WU Fangwen1,HE Lanqing1,DUAN Junqi1,WANG Guangqian1,LIU Laijun1,YANG Fei2
|
|
(1.School of Highway, Chang′an University, Xi′an 710064, China; 2.School of Civil Engineering, Chang′an University, Xi′an 710061, China)
|
| Abstract: |
| To investigate the mechanical performance and microscopic characteristics of Engineered Cementitious Composite (ECC) after high temperatures, material mechanical tests and microscopic observations of ECC after high temperatures were conducted. The compressive tests and the bending tests of ECC specimens were carried out after natural cooling and spray cooling methods at room temperature (25 ℃), 200 ℃, 300 ℃, 400 ℃, and 500 ℃ and analyzed the failure characteristics of ECC microstructure by scanning electron microscope, and investigated the damage mechanism of ECC after high temperatures. The results show that the concrete on the surface of ECC does not peel off after high temperatures, and there is no burst phenomenon within 500 ℃. As the temperature increases, the fiber gradually melts from the surface of the concrete to the inside, the water loss increases and the maximum burning loss rate is 13.9%. In terms of mechanical properties, the compressive strength of ECC after natural cooling decreases first then increases, and then decreases with the increase in temperature. After water spray cooling, the compressive strength decreases monotonously with the increase in temperature, and the strength decreases significantly. The flexural strength after high temperature decreases gradually with the increase in temperature, and the decrease of natural cooling is more significant than that of water cooling. Combined with the change of microstructure, when ECC undergoes high temperature, the partial melting of the fiber leads to the weakening of the bonding performance between the fiber and the matrix. With the increase in temperature, the hydration products gradually show independent dispersion. However, the secondary hydration of unhydrated particles after water spray cooling is evident, which makes the flexural strength of ECC increase by 17% compared with natural cooling. ECC has excellent thermal stability, and cooling methods influence the apparent characteristics, mechanical properties, and microscopic characteristics of ECC. |
| Key words: bridge engineering mechanical properties high-temperature experiment engineered cementitious composite microstructure cooling modes |
|
|
|
|
