减缩剂预饱和轻骨料对水泥砂浆自收缩的影响及机理  

Influence and Mechanism of Lightweight Aggregates Pre-Saturated with Shrinkage Reducing Admixtures on Autogenous Shrinkage of Cement Mortar

作　　者：党玉栋[1] 钱觉时[1] 乔墩[1] 张琳[1] 贾兴文[1] 陆福高[1] 

机构地区：[1]重庆大学材料科学与工程学院,重庆400045

出　　处：《硅酸盐学报》2011年第1期47-53,共7页Journal of The Chinese Ceramic Society

基　　金：西部交通科技项目(2009318000033);重庆市科技攻关项目(CSTC2009AC6204)资助

摘　　要：使用内养护(IC)和减缩剂(SRA)是两种可有效降低水泥基材料自收缩的方法,但两者单独采用时存在明显不足。试验研究了减缩剂预饱和的轻骨料对水泥砂浆自收缩、强度、水化程度以及骨料–水泥石基体界面过渡区域的影响。结果表明:由于减缩剂降低溶液表面张力并增加溶液黏度,减缩剂溶液相比水从轻骨料中释放速率明显降低;与直接内掺减缩剂相比,当减缩剂引入量相等时,减缩剂预饱和轻骨料对砂浆自收缩降低程度相近,但其对砂浆强度不利影响则大大降低;与饱水轻骨料内养护措施相比,减缩剂预饱和轻骨料能够显著降低砂浆的自收缩,明显改善骨料与浆体界面区域的孔隙率和微观结构。Internal curing（IC） and utilizing the shrinkage reducing admixture（SRA） are two effective methods of autogenous shrinkage mitigation.However,IC and SRA have some marked deficiencies when they are used individually.This paper investigated the influences of light weight aggregates pre-saturated with shrinkage reducing admixtures（SRA–LWA） on the autogenous shrinkage and strength of cement mortar;meanwhile,the effects of SRA-LWA on hydration degree and microstructure of interfacial transition zone（ITZ） were also examined.The results indicate that the SRA could reduce the release rate of solution by decreasing the solution＇s surface tension and increasing the viscosity.With the same amount of SRA,the ability of autogenous shrinkage reduction of SRA-LWA was similar to that of the SRA mixed with cement mortar（SRA–Mixed）.However,the SRA–LWA could diminish the adverse impacts of SRA on cement hydration and strength of cement mortar significantly.Further,comparing to light weight aggre-gates pre-saturated with water（Water–LWA）,the SRA-LWA had a more remarkable contribution to shrinkage reduction,and showed the evidence of lower porosity and denser microstructure of ITZ nearby the LWA.

关 键 词：自收缩 内养护 减缩剂 轻骨科 界面过渡区 表面张力 

分 类 号：TU528.042[建筑科学—建筑技术科学]