钙镁复合膨胀剂对不同温度历程混凝土的变形性能的影响  

Effect of CaO-MgO composite expansive agent on deformation performance of concrete with different temperature histories

作　　者：张小鹏 陆安群[2,3] 倾涛 张戎令 徐文[6] 蔡佳豪[1] ZHANG Xiaopeng;LU Anqun;QING Tao;ZHANG Rongling;XU Wen;CAI Jiahao(Gansu Changda Highway Co.,Ltd.,Lanzhou 730000,China;State Key Laboratory of High Performance Civil Engineering Materials,Jiangsu Research Institute of Building Science,Nanjing 210008,China;Jiangsu Sobute New Materials Co.,Ltd.,Nanjing 211103,China;China Railway Bridge Bureau Group First Engineering Co.,Ltd.,Zhengzhou 450053,China;School of Civil Engineering,Lanzhou Jiaotong University,Lanzhou 730070,China;School of Materials Science and Engineering,Southeast University,Nanjing 211189,China)

机构地区：[1]甘肃省长达路业有限责任公司,甘肃兰州730000 [2]江苏省建筑科学研究院有限公司高性能土木工程材料国家重点实验室,江苏南京210008 [3]江苏苏博特新材料股份有限公司,江苏南京211103 [4]中铁大桥局集团第一工程有限公司,河南郑州450053 [5]兰州交通大学土木工程学院,甘肃兰州730070 [6]东南大学材料科学与工程学院,江苏南京211189

出　　处：《混凝土》2024年第10期105-110,共6页Concrete

基　　金：国家自然科学基金(52378239);武九高速尖山沟特大钢管拱桥关键技术研究及应用(21YF11GA011)。

摘　　要：依据不同尺寸结构混凝土的温度历程,设计适宜的膨胀剂,可有效降低混凝土开裂风险。研究恒温条件、变温条件下的混凝土温度对氧化钙膨胀剂、钙镁复合膨胀剂的膨胀效能的影响规律。结果表明:40℃恒温条件下,6%CaO膨胀剂的混凝土早期表现出较大膨胀变形,但在5 d内基本膨胀完全;掺4%CaO+2%MgO(250 s)的混凝土28 d龄期内持续膨胀。变温条件下,低活性MgO膨胀剂在温降阶段膨胀性能的发挥需要适宜的温度条件,最高温度越高、降温速率越慢(即在较高温度维持的时间越长)越有利于MgO膨胀剂膨胀性能的发挥。最高温度超过40℃、早期(前5 d)温降速率低于4.5℃/d,降温时间持续较长的情况下,活性值为250 s的MgO膨胀剂在混凝土温降阶段才能发挥膨胀补偿温降收缩的效果。According to the temperature history of concrete with different sizes,appropriate expansive agent can be designed to effectively reduce the risk of concrete cracking.It studies the effect of CaO expansive agent and CaO-MgO composite expansive agent on deformation performance of concrete with different temperature histories.The results show that under the constant temperature of 40℃,the concrete with 6%CaO expansive agent shows large expansion deformation at the early stage,but the expansion is basically complete within 5 days.The concrete mixed with 4%CaO+2%MgO(250 s)expansive agent continues to expand within 28 days.Under variable temperature conditions,the expansion performance of low-activity MgO expansive agent needs appropriate temperature conditions at the temperature drop stage.The higher the maximum temperature,the slower the cooling rate(i.e.,the longer the duration at higher temperature),the more conducive to the expansion performance of MgO expansive agent.When the maximum temperature exceeds 40℃,the temperature drop rate in the early stage(the first 5 days)is lower than 4.5℃/d,and the cooling time lasts for a long time,the MgO expansive agent with an activity value of 250 s can play the effect of expansion compensation for temperature drop and shrinkage in the temperature drop stage.

关 键 词：钙镁复合膨胀剂 补偿收缩混凝土 温度历程 变形性能 

分 类 号：TU528.042.4[建筑科学—建筑技术科学]