Abstract

Fibers have been successfully adopted as reinforcing phase to improve the properties of materials and structures due to their excellent anti-cracking performance[1].The reinforced efficiency is significantly influenced by the distribution_of fiber[2].Many researchers[3-6]have analyzed the distribution or orientation of steel fibers in steel fiber reinforced concrete(SFRC),however,there is a lack of study focusing on the short flexible fiber distribution in fiber reinforced concrete(FRC).In this paper,Nano-CT analyses were adopted firstly to reveal a detailed microstructure of glass fiber reinforced concrete,the typical“slice”of the sample and the 3D distribution of glass fiber in FRC were shown in Figure 1,respectively,in which the physical extent was 2.99 mm×2.99 mm×2.99 mm.

Figure 1　Image of glass fiber reinforced concrete from Nano-CT

Additionally,the distribution of glass fiber in FRC was analyzed using statistical theory.Here the inclination angle of glass fiber,θandφ were illustrated in Figure 2,and the probability density histogram ofθandφ were described in Figure 3.It can be seen in Figure 3(a)that most of theθ was between in 80°and 90°,whileφ was mainly in the range from 0°to 30°。

Figure 2　The inclination angles of glass fiber

According to previous researches in references[4-6],the parameters used to describe fiber orientationη1,η2,η3, and S were summarized in Table 1.It can be obtained from Table 1 thatη1 equaled to 0.97,which was larger than eitherη2 orη3.This indicated the glass fibers mostly tended to XOY plane.Moreover,equaled to 10.81,which was smaller than either.This also means the glass fibers more tended to XOY plane than either YOZ plane or XOZ plane.

Figure 3　Probability density histogram of inclination angle

Table 1　Summary of the fiber distribution parameters of the samples