Research on Chloride Penetration Resistance of Hybrid Fiber Reinforced Self-Compacting Concrete
The properties of chloride penetration of hybrid fiber reinforced self-compacting concrete (SCC) were investigated in this study. The results show that the chloride penetration resistance of concrete can be improved by single incorporation either carbon or cellulose fibers. The concrete chloride diffusion coefficient DRCM of 12-cm length carbon SCC with fiber content of 1.7, 2.72, and 3.4 kg/m3 decreases by 10.3, 25.5, and 18.2% compared to reference concrete without any fibers, respectively. Moreover, the concrete chloride diffusion coefficient DRCM of cellulose SCC with fiber content of 1.2, 1.6, and 2.0 kg/m3 decreases by 18.8, 22.4, and 26.7% compared to reference concrete, respectively. Based on the results of orthogonal experimental design, the chloride diffusion coefficients DRCM of hybrid fiber reinforced SCC are listed in order of importance, as follows: length of carbon fiber > content of carbon fiber > content of cellulose fiber; furthermore, the hybrid of 2.72-kg/m3 carbon fiber with length of 12 mm and 2.0-kg/m3 cellulose fiber exhibits the most significant effect on chloride diffusion coefficients DRCM of SCC.
Mechanical response and shrinkage performance of cementitious composites with a new fiber hybridization
Abstract A new kind of fiber hybridization containing steel fibers, polyvinyl alcohol (PVA) fibers and cheap calcium carbonate (CaCO 3 ) whiskers (approximately $230 per ton) was designed to improve the mechanical response and shrinkage performance as well as reduce the production cost of fiber reinforced cementitious composites. Compressive response, flexural response, drying shrinkage and plastic shrinkage of this designed hybrid fiber reinforced composites were presented. The results indicated that the designed hybrid fiber shows a significant positive hybrid effect on mechanical response and plastic shrinkage of cementitious composites. Steel fibers are more effective in restricting drying shrinkage. PVA fibers and CaCO 3 whiskers are more effective in restraining plastic shrinkage. Good mechanical response and satisfactory shrinkage performance of the designed hybrid fiber reinforced cementitious composites make it possible to partly replace the steel fibers and PVA fibers by using CaCO 3 whisker, thus helping to decrease the production cost of fiber reinforced cementitious composites for large scale construction project applications in the future.
The qualitative research interview
Background  Interviews are among the most familiar strategies for collecting qualitative data. The different qualitative interviewing strategies in common use emerged from diverse disciplinary perspectives resulting in a wide variation among interviewing approaches. Unlike the highly structured survey interviews and questionnaires used in epidemiology and most health services research, we examine less structured interview strategies in which the person interviewed is more a participant in meaning making than a conduit from which information is retrieved.