新型AS界面剂对新老混凝土界面粘结性能的影响及机理

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研究了新型 AS界面剂对自然养护条件下新老混凝土界面粘结性能的影响及机理，结果表明，自然养护条件下，与低水灰
比水泥净浆处理相比，AS界面剂处理时早期界面粘结强度较低，与未经处理时相当，但未经处理及低水灰比水泥净浆处理时，在较
早养护龄期 (7 d后)即开始出现强度倒缩；采用 AS界面剂处理时，其界面粘结强度的增长与界面剂组分有关，以硅粉为主时，28 d
后强度也有所倒缩，以粉煤灰为主时，56d内强度均持续增长，其原因是由于新老混凝土变形差异过大形成界面剪切应力，导致过早
形成的界面粘结结构局部破坏所致，而采用粉煤灰为主的新型 AS界面剂处理时，其界面粘结作用则随养护龄期延长而缓慢形成，
因而界面粘结强度得以持续增长。
关键词：界面剂；新老混凝土界面粘结；硅粉；粉煤灰；硅溶胶
中图分类号：TU528．044 文献标识码：B 文章编号：1001—702X(2010)01—0005—03
Effect and m echanism of novel AS interfacial agent on the bonding strength of fresh——old concrete
FENG Yinghui ，ZHANG Men~fanf，KONG Deyu ，MA Chengchanf，JIANG ,lun
(1．Hangzhou Urban Construction Institute，Hangzhou 310012，Zhejiang，China：
2．Faculty of Civil Engineering and Architecture，Zhejiang University of Technology，Hangzhou 310014，Zhejiang，China：
3．Hangzhou Construction & Building Materials Co．Ltd．，Hangzhou 3 1 1 107，Zh~iang，China)
Abstract：Effect and mechanism of novel AS interfacial agent on the bonding strength of fresh-old concrete under natural
curing condition were investigated in this paper．The results showed that under natural curing condition，compared with the treatment with low water-cement—ratio cement paste(LW C)，the bonding strength at early curing age by using the novel interfaeial agent
was relatively lower，and WaS just as comparable to that without interfaeial treatment．However，the bonding strength showed decreaS e after curing for 7 days while using LW C as interfacial agent or without treatment：while using the novel interracial agent，the
increaS e of its bonding strength is related to the components of the interfacial agent．The bonding strength also showed decrease
after 28 days while using the novel interfaeial agent with silica fume as the main component． W hen fly ash was used as main
component，the bonding strength showed a continuous increase within 56 days．The main reaSon was that shear stress WaS formed
due to big deformation difference between the old and the fresh concrete，which resulted in partial destru ction of the early—formed
adhesion．On the other hand，when novel interracial agent with fly ash as the main component WaS used，its adhesion was formed
slowly with the prolongation of the curing time．As a result，the bonding strength of the interface can be increased continuously．
Key words：interfacial agent；adhesion of fresh—old concrete；silica fume；fly ash：silica sol
在结构维护、改造、加固和新建工程装修以及混凝土制品
修补时，经常涉及新老混凝土的界面粘结问题，其界面粘结好
坏直接影响工程和制品质量。研究发现，由于老混凝土表
基金项目：浙江省建设厅项目(200721)
杭州市科技计划项目(20o7O733B20)
收稿日期：2009—08—18
作者简介：冯颖慧，女，1975年生，河北大名人，硕士，高级工程师。地
址：杭州市新华路 7O号，电话：13105717881，E—mail：~h75@163．eom。
面具有较强亲水性和吸水性，未经处理的新老混凝土界面亦
存在类似于混凝土中骨料与水泥石界面过渡区的薄弱层，在
老混凝土表面孔隙及新老混凝土界面存在氢氧化钙(CH)和
钙矾石(AFt)晶体的富集现象，其界面粘结性能往往较差13]。为
提高界面粘结强度，目前工程中普遍采用混凝土界面剂，包括
无机界面剂翻和有机一无机复合界面剂141两大类，一般均配制
成低水灰比净浆或砂浆进行界面处理，界面剂用量大，成本
高。孔德玉等【在分析新老混凝土界面微观结构的基础上，开
发了一种新型 AS界面处理剂，经 AS界面剂处理后，可在老