自然养护条件下MEA混凝土早期体积变形及力学性能  

Effects of natural environment on the early deformation and mechanical properties of MgO-base expansive concrete

作　　者：余兰清 张德健 曾浪 邓敏[2] YU Lanqing;ZHANG Dejian;ZENG Lang;DENG Min(State Key Laboratory of High Performance Civil Engineering Materials,Jiangsu Sobute New Materials Co.,Ltd.,Nanjing 211103,China;College of Materials Science and Engineering,Nanjing Tech University,Nanjing 211816,China)

机构地区：[1]江苏苏博特新材料有限公司高性能土木工程材料国家重点实验室,江苏南京211103 [2]南京工业大学材料科学与工程学院,江苏南京211816

出　　处：《混凝土》2023年第3期189-192,共4页Concrete

摘　　要：MgO膨胀剂(MEA)目前在工民建工程领域抗裂防渗的应用研究较少。针对工民建领域混凝土易出现早期开裂问题,将两种轻烧MEA(60、220 s)以不同的掺量(8%和10%)掺入到混凝土墙中。采用振弦应变计监测自然养护条件下混凝土的早期变形及温度历程,并测定了同条件养护下不同龄期(7、28、90 d)的混凝土抗压强度,研究了自然条件下轻烧MEA混凝土的早期变形及力学性能规律。结果表明:春夏季浇筑的0.8 m厚混凝土墙,1.2 d抵达温度峰值55~71℃,掺量为8%和10%MEA约产生30~60με的无效膨胀;随后温度持续下降6~7 d,8%MEA在这个阶段产生了70~110με膨胀,收缩补偿率约22%~36%;10%MEA产生了120~150με膨胀,收缩补偿率38%~48%。在随后的环境温度阶段,到12 d时MEA的水化膨胀明显减缓甚至停止。内掺MEA导致混凝土早期强度下降明显,后期强度逐渐接近标准混凝土,但掺量不宜超过8%。There is a few application researches about MgO expansive agent(MEA)that applied to civil engineering construction.For coping with early-crack problem of concrete in civil engineering construction,two kinds of MEAs(60 s and 220 s)were added into concrete walls with different contents(8%and 10%).Early deformation and temperature history of concrete wall were monitored by strain transducer,the compressive strength of concrete curing in the field at different ages(7,28 d and 90 d)was determined,then effects of natural environment on the early deformation and mechanical properties of MEA were investigated.The results showed that temperature peak is 55℃to 71℃and 8%and 10%contents of MEA generated 30μεto 60μεinefficient expansive deformation when concrete wall poured in the spring and summer.Then temperature declined continuously last for 6 d to 7 d.During this stage,8%contents of MEA generated 70μεto 110μεexpansive deformation and the ratio of shrinkage-compensating was 22%to 36%.10%contents of MEA generated 120μεto 150μεexpansive deformation and the ratio of shrinkage-compensating was 38%to 48%.Deformation generated by MEA was slow down obviously and even stopped during the environment stage.When MEA was added into concrete,the early compressive strength was declined obviously and then closed to reference concrete with prolonging age,but the amount of MEA added into concrete was not suitable to exceed 8%.

关 键 词：工民建工程 自然养护条件 氧化镁膨胀剂 早期变形 力学性能 

分 类 号：TU528.064[建筑科学—建筑技术科学]