The effect of hybrid fibers and expansive agent on the shrinkage and permeability of high-performance concrete

Abstract

In this paper, high-performance concrete (HPC) incorporated with expansive agent and hybrid fibers, i.e., steel fibers, polyvinyl alcohol fiber (PVA fiber), and polypropylene fiber (PP fiber), was produced. The properties measured included shrinkage and water permeation of the concrete. The effect of hybrid fibers and/or expansive agent on the shrinkage and water permeation properties was investigated. Test results indicated that the hybrid fibers of different types and sizes could reduce the size and amount of crack source at different scales; hybrid fibers combined with expansive agent provided better enhancement for shrinkage resistance and impermeability of HPC than monoincorporation of hybrid fibers or expansive agent; the improvement of the shrinkage resistance and the impermeability of the concrete resulted from the combined use of expansive agent and hybrid fibers, which was dependent on the amount of expansive agent, types and sizes of hybrid fibers, total volume fraction of fibers, proportions of hybrid fibers, and so on. The relevant mechanisms were also discussed based on the analysis of the test results of pore structure of the concrete.