Research on fiber reinforced concrete and its performance prediction method and mix design method

Abstract

To better solve the problems of performance prediction and mix design of fiber reinforced concrete (FRC), this paper carried out relevant research based on different kinds of fibers. First, according to the existing results and experimental research, fibers of various scales are selected preliminarily. Then, based on the mechanical property test, the fiber selection, fiber content and fiber hybrid mode are studied, and the fiber action mechanism is revealed through the failure process analysis and microscopic observation. Then, based on the newly constructed fiber reinforcement factor (S), a FRC strength prediction model was established. Finally, by combining S with hybrid fiber effect coefficient (RH) based on comprehensive properties, a method for FRC mix design is formed. The research results and conclusions are as follows: Steel fiber (SF), Short macroscopic polyvinyl alcohol fiber (SMP), fine polyvinyl alcohol fiber (PVA) and Calcium carbonate whisker (CW) have better performance improvement effects in their respective scales, and the content of SF, SMP, PVA and CW with the highest cost performance ratio is 2%, 0.75%, 0.5% and 1% respectively. Micro observation shows that CW not only has the effect of “micro filler” and “microfiber”, but also has the effect of friction resistance at the interface between reinforcement fiber and substrate. According to the mechanical property data and RH value, the best sample group is the sample containing 1.5% SF, 0.5% SMP and 1% CW. In addition, 1.5% SF and 0.5% SMP can also produce good performance when mixed with 1% CW respectively. The regression analysis results show that the FRC strength prediction model established in this paper has good regression coefficients. The mix design method of FRC based on S and RH can provide reference for the research and production of FRC.