| 高原低气压对道路工程混凝土性能的影响及原因 |
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| 引用本文： | 李扬,王振地,薛成,白永厚,王玲.高原低气压对道路工程混凝土性能的影响及原因[J].中国公路学报,2021,34(9):194-202. |
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| 作者姓名： | 李扬 王振地 薛成 白永厚 王玲 |
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| 作者单位： | 1. 中国建筑材料科学研究总院有限公司 绿色建筑材料国家重点实验室, 北京 100024;2. 北京建筑材料科学研究总院有限公司 固废资源化利用与节能建材国家重点实验室, 北京 100041;3. 中交第二公路工程局有限公司, 陕西 西安 710065;4. 中交二公局第四工程有限公司, 河南 洛阳 471013 |
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| 基金项目： | 国家重点研发计划项目（2017YFB0309903） |
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| 摘 要： | 为研究高原低气压对道路工程混凝土性能的影响，在拉萨（气压约60 kPa）和北京（气压约100 kPa）两地采用相同配合比的道路混凝土分别进行性能对比试验，测试了混凝土含气量、坍落度、强度、NEL法氯离子渗透系数和单面盐冻耐久性等性能指标，进一步测定了引气剂溶液的泡沫体积、表面张力和硬化混凝土孔结构。试验结果表明：在低气压下，引气混凝土的含气量和坍落度分别比常压下降低8%~36%和4%~9%；抗压强度和劈裂抗拉强度分别比常压下降低1.6%~14.8%和1.5%~10.8%；氯离子渗透系数比常压下增加29%~135%；可见低气压下其抗冻耐久性降低。在低气压下，引气剂溶液的表面张力比常压下增加3.0%~4.5%，溶液泡沫体积比常压下降低2%~14%，混凝土内的气体压缩系数比常压下减小，这些原因导致了低气压环境下施工的道路混凝土含气量降低，坍落度减小；与此同时，硬化混凝土平均气孔直径增大6%~18%，气泡间距系数增加45%~92%，最终使得低气压下混凝土强度、抗氯离子渗透性和抗冻耐久性降低。
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| 关 键 词： | 道路工程 混凝土耐久性 气孔结构 高原混凝土 低气压 引气剂 |
| 收稿时间： | 2020-01-09 |
Influence of Low Air Pressure on the Performance of Concrete in Road Engineering |
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| LI Yang,WANG Zhen-di,XUE Cheng,BAI Yong-hou,WANG Ling.Influence of Low Air Pressure on the Performance of Concrete in Road Engineering[J].China Journal of Highway and Transport,2021,34(9):194-202. |
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| Authors: | LI Yang WANG Zhen-di XUE Cheng BAI Yong-hou WANG Ling |
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| Affiliation: | 1. State Key Laboratory of Green Building Materials, China Building Materials Academy, Beijing 100024, China;2. State Key Laboratory of Solid Waste Reuse for Building Materials, Beijing Building Materials Academy of Sciences Research, Beijing 100041, China;3. CCCC Second Highway Engineering Co., Ltd., Xi'an 710065, Shaanxi, China;4. CCCC-SHB Fourth Engineering Co., Ltd., Luoyang 471013, Henan, China |
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| Abstract: | To study the influence of high altitude low pressure on the performance of concrete in road engineering, the performance of road concrete with the same mix ratio in Lhasa (air pressure of approximately 60 kPa) and Beijing (air pressure of approximately 100 kPa) was compared. The air content, slump, compressive and flexural strengths, chloride ion permeability coefficient based on the NEL, and the freeze-thaw resistance of concrete based on single-side freezing and thawing were tested. The foam volume and surface tension of the air entraining agent and the pore structure of the hardened concrete were investigated. The test results show that under low air pressure, the air content and slump of the concrete were 8%-36% and 4%-9% lower than that under normal air pressure, respectively. The compressive strength and splitting tensile strength were 1.6%-14.8% and 1.5%-10.8% lower than those under normal air pressure, respectively; the chloride permeability coefficient was 29%-135% higher than that under normal air pressure, and the durability of concrete was reduced. Under low air pressure, the surface tension of the air entraining agent was 3.0%-4.5% higher than that under atmospheric pressure, the volume of the solution foam was 2%-14% lower than that under atmospheric pressure, and the gas compression coefficient in concrete decreased compared to that under atmospheric pressure. These phenomena caused a decrease in the air content and slump of the road concrete under a low air pressure environment. The average pore diameter of hardened concrete increased by 6% to 18%, and the bubble spacing factor increased by 45% to 92%, which ultimately reduced the strength, resistance to chloride ion permeability, and freeze-thaw resistance of concrete. |
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| Keywords: | road engineering concrete durability pore structure plateau concrete low air pressure air entraining agent |
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