CONTROL OF SHRINKAGE CRACKING DUE TO AUTOGENOUS AND DRYING SRINKAGE
Concrete shrink when it is subjected to drying whenever its surfaces are exposed toair of low relative humidity. Since various kinds of restraint prevent the concrete fromcontracting freely,cracking should be occurred. This shrinkage cracking is a critical problemin concrete construction,in particular for thin and flat structures such as walls and slabs ofbuilding,highway pavement,and bridge decks.,unless the ambient relative humidity is keptnear 100％. This paper reviews the mechanism,the influencing factors and the controlmeasures of shrinkage induced cracking due to autogenous and drying shrinkage. The controlof cracking consists of reducing the cracking tendency to a minimum,using adequate andproperly positioned reinforcement,and using contraction joints. In addition,the use of propercuring practices that minimize evaporative losses or supply additional water can substantiallyreduce shrinkage. This paper also describes the efficient of shrinkage reducing admixtures(SRAs) in controlling restrained shrinkage cracking of concrete. The study on mechanism ofshrinkage shows that the autogenous shrinkage may be closely related to the chemicalpotential of water in cement systems. This leads to the possibly that the disjoining pressurealso acted as a driving force for SRA to reduce the shrinkage.
concrete autogenous shrinkage drying shrinkage restrain cracking shrinkage-reducing agent
Toyoharu Nawa
Division of Solid Waste,Resources and Geo-environmental Engineering,Hokkaido University,Japan
国际会议
The International Conference on Durability of Concrete Structures(2008年混凝土结构耐久性国际学术会议)
杭州
英文
126-136
2008-11-01（万方平台首次上网日期，不代表论文的发表时间）