Author(s): KONG Xiangming, ZHANG Zhenlin, Key Laboratory of Safety and Durability of China Education Ministry, Department of Civil Engineering, Tsinghua University
Pages: 150-155
Year: 2014 Issue:  2
Journal: Journal of the Chinese Ceramic Society
Keyword:  high-strength concrete; super-absorbent polymer; autogenous shrinkage; mechanism of shrinkage reduction; model;
Abstract: Shrinkage-reducing effect of super-absorbent polymer(SAP)as an internal curing agent in high-strength concrete(HSC)was experimentally investigated.A quantitative analysis of its mechanism was conducted based on the capillary stress based model.The experimental results show that the pre-soaked SAP decreases the autogenous shrinkage and the reduction ratio can reach 90%,compared to the reference samples.The experimental shrinkage curves of HSCs at different mix proportions fit the simulated data obtained by the model.The simulated results show that there are mainly two factors contributing to the shrinkage-reducing effect of pre-soaked SAP.At the moisture saturated stage(the relative humidity,RH=100%),the presoaked SAP causes an expansive deformation that compensates the ordinary chemical shrinkage to some extent.When the internal RH reduces<100%,the addition of pre-soaked SAP mitigates the RH reduction process,delays the decline of the critical pore radius and reduces the capillary pressure of concrete.The driving force of autogenous shrinkage is thus reduced.