掺MgO膨胀剂的面板混凝土早龄期热膨胀系数  

Effect of MgO on the Early-age Thermal Expansion Coefficient of Face Slab Concrete Based on Temperature Stress Tests

作　　者：钟可 赵志方[1] 朱敏敏[2] 方博 王建东[1] 施韬[1] ZHONG Ke;ZHAO Zhifang;ZHU Minmin;FANG Bo;WANG Jiandong;SHI Tao(Zhejiang University of Technology,College of Civil Engineering,Hangzhou 310023,China;Zhejiang College of Construction,Hangzhou 311231,China;Wuhan Sanyuan Special Building Materials Co.,Ltd.,Wuhan 430083,China)

机构地区：[1]浙江工业大学土木工程学院,浙江杭州310023 [2]浙江建设职业技术学院,浙江杭州311231 [3]武汉三源特种建材有限责任公司,湖北武汉430083

出　　处：《材料科学与工程学报》2023年第6期968-973,共6页Journal of Materials Science and Engineering

基　　金：国家自然科学基金项目(52279142,52378270)。

摘　　要：掺入MgO膨胀剂能补偿混凝土的温度收缩,有望改善堆石坝面板混凝土的抗裂性。为了研究MgO膨胀剂对面板混凝土早龄期热膨胀系数的影响,本实验对基于施工配合比的基准面板混凝土(JC)和掺入5 wt%MgO膨胀剂的面板混凝土(PC)进行了温度-应力试验。通过测试恒温养护(CTC)和温度匹配养护(TMC)两种模式下面板混凝土的自由应变,采用等效龄期下的应变差和温度差来确定两种面板混凝土的早龄期的热膨胀系数(CTE)。试验结果表明,两种面板混凝土的早龄期CTE都具有时变性,其CTE在终凝后快速降低,最后趋于稳定值。与JC相比,掺入MgO膨胀剂能够略微增加PC的CTE。MgO可能导致混凝土水化消耗的水分略微增加,其膨胀产物氢氧化镁的填充作用能够降低面板混凝土的孔隙率,二者共同作用略微增大了面板混凝土的CTE。The incorporation of MgO expansive agent can compensate the temperature shrinkage of concrete,which is expected to improve the crack resistance of the face slab concrete of a rockfill dam.The coefficient of thermal expansion(CTE)of concrete is an important factor affecting temperature deformation.In order to study the effect of MgO expansive agent on the CTE of the face slab concrete at early age,the temperature-stress test was carried out on the benchmark face slab concrete(JC)based on the construction mix ratio and the face slab concrete(PC)with 5 wt%MgO expansive agent.By testing the free strain of face slab concrete under the two modes of constant temperature curing(CTC)and temperature matching curing(TMC),the strain difference and temperature difference at the equivalent age were used to determine the earlyage CTE of the two face slab concretes.The test results show that the early age CTE of the two face slab concretes is time-varying,and the CTE decreases rapidly after final setting,and finally tends to a stable value.Compared with JC,MgO expansion agent could slightly increase the CTE of PC.MgO could lead to a slight increase in the water consumed by hydration of concrete,and the filling effect of its expansion product magnesium hydroxide could reduce the porosity of face slab concrete.The combined effect of the two slightly increases the CTE of face slab concrete.

关 键 词：面板混凝土 MGO膨胀剂 热膨胀系数 温度-应力试验 早龄期 

分 类 号：TU528[建筑科学—建筑技术科学]