Abstract

Info

Title:: Influence of Constrained Shrinkage Cracking on Chloride Ion Diffusivity of High Performance Concrete

Author(s):: MA Li-na; GONG Jin-xin; ZHAO Yan-hua; Faculty of Infrastructure Engineering, Dalian University of Technology

Keywords:: high performance concrete; doublemixed mineral admixture; shrinkage; cracking; diffusion coefficient of chloride ion

Abstract:: Plate shrinkage test and fast chloride diffusion coefficient test (RCM method) of high performance concrete with total amount of fly ash (FA) and granulated blast furnace slag (GGBFS) of 30%,40% and 50% by mass of binder and ratio of FA to GGBFS 1∶2, 2∶3 and 1∶1 were carried out. The constrained and unconstrained shrinkage cracking behavior of high performance concrete and its influence on chloride diffusion coefficient were analyzed. The results show that the unconstrained concrete slabs have no cracks, and the constrained concrete slabs all crack. The crack resistance of concrete is significantly improved by mixing FA and GGBFS. The crack resistance is best when the mixing ratio of FA and GGBFS is 1∶1. With the increase of FA and GGBFS dosage, the crack resistance of concrete is better. The equivalent chloride ion diffusion coefficient of constrained concrete is higher than that of unconstrained concrete with the same total amount of FA and GGBFS and ratio of FA to GGBFS. The constraint shrinkage crack increases the concrete chloride ion diffusion coefficient. The concrete chloride ion resistance is getting worse with the increase of concrete shrinkage strain. When mixing ratio of FA and GGBFS is 1∶1, the influence of constraint shrinkage of concrete on chloride ion diffusion is minimal.