外掺氧化镁面板混凝土力学及变形性能试验研究  

Experimental Study on Mechanical and Deformation Properties of Face Concrete mixed with Magnesium Oxide

作　　者：陈书军 王保欣 项立鑫 李志龙 董博 CHEN Shujun;WANG Baoxin;XIANG Lixin;LI Zhilong;DONG Bo(PowerChina Sinohydro Bureau 3 Co., Ltd., Xi'an 710024,China;PowerChina Northwest Engineering Corporation Limited, Xi'an 710065,China)

机构地区：[1]中国水利水电第三工程局有限公司,西安710024 [2]中国电建集团西北勘测设计研究院有限公司,西安710100

出　　处：《西北水电》2022年第2期51-56,共6页Northwest Hydropower

摘　　要：为有效降低某抽水蓄能电站上水库面板混凝土存在开裂问题,开展了基准混凝土、外掺氧化镁膨胀剂混凝土和外掺硫铝酸盐CSA膨胀剂混凝土的力学性能、抗冻性能以及抗裂性能的对比试验研究。结果表明:相比于基准组,外掺氧化镁膨胀剂会降低混凝土的早期抗压强度,采用小于0.41水胶比配制的混凝土抗压强度(28 d)可满足43.2 MPa的配制强度要求;水胶比相同时,掺入CSA膨胀剂混凝土和掺氧化镁膨胀剂混凝土的极限拉伸值(90 d)较基准组分别提高了约36.3%和41.8%。随着冻融循环次数的增加,氧化镁水化产生的Mg(OH)_(2)均有效填充混凝土内部孔隙,且有不断增长的趋势,混凝土动弹模量也随之相对较高,满足抗冻等级F400的要求;由混凝土大板干缩试验结果可知,外掺适量的MgO和CSA膨胀剂均可以不同程度地减少混凝土自生体积收缩,掺入MgO或掺入CSA膨胀剂对抑制混凝土面板早期裂缝效果较好。In order to effectively reduce the cracking problem of the face concrete in the upper reservoir of a pumped storage power station,the mechanical properties,frost resistance and anti-corrosion properties of reference concrete,concrete mixed with magnesia expansion agent and concrete mixed with sulfoaluminate CSA expansion agent were studied through comparative experiment.The results show that:compared with the reference group,the addition of magnesium oxide expansion agent will reduce the early compressive strength of concrete,and the compressive strength(28 d)of concrete prepared with a water-binder ratio of less than 0.41 can meet the preparation strength requirement of 43.2 MPa;Under the same water-binder ratio,the ultimate tensile value(90 d)of the concrete mixed with CSA expansion agent and the concrete mixed with magnesia expansion agent increased by about 36.3%and 41.8%respectively compared with the reference group.With the increase of the number of freeze-thaw cycles,the Mg(OH)_(2) produced by the hydration of magnesium oxide can effectively fill the internal pores of the concrete,and its dynamic modulus is relatively high,which meets the requirements of frost resistance grade F400;from the dry shrinkage test results of large concrete slabs,it can be seen that the addition of appropriate amounts of MgO and CSA expansion agent can reduce the autogenous volume shrinkage of concrete to varying degrees,and the addition of MgO or the addition of CSA expansion agent can inhibit the early cracks of concrete panels.

关 键 词：面板混凝土 氧化镁 自身体积变形 抗裂性能 

分 类 号：TV213.9[水利工程—水文学及水资源]